C.1.
PREPARATION AND SEPARATION
TEMPLATE POLYMERIZATION
Saeed Al-Alawi and N. A. Saeed
Macromolecules (1990), 23, 4474-4476
OF
COMPLEXES
PREPARED
BY
ABSTRACT
Acrylic acid (AA) was polymerized in the presence of poly(vinylpyrrolidone) (PVP) as a
template polymer in an aqueous medium. The result was a complex of poly(acrylic acid) (PAA)
and PVP. Comparison of the FTIR spectrum of the complex with that prepared by mixing of
PAA and PVP indicates that the complex is composed of PAA and PVP. The separation of the
complex was achieved by methylation, indicating that the polymers were interacting through
hydrogen bonding. The low yield of separation indicates the existence of some grafted complex.
When the complex was prepared by using PVP of different molecular weights, the yield of
separation changed. The degree of the separation decreased as the molecular weight of PVP
increased.
C.2.
STUDIES
ON
THE
COMPLEXES
PREPARED
POLYMERIZATION.1. EFFECT OF MOLECULAR WEIGHT
S.S. Al-Alawi
Macromolecules (1991), 24,: 4206 - 4208
BY
TEMPLATE
ABSTRACT
It is known that macromoleculecules in solution have a strong tendency to interact with each
other to form a super molecular structure through various secondary binding forces, and
hydrophobic interactions. There are various factors that effect the degree of complex formation
and ability of stabilization, namely, the molecular weight of the reacting chain, concentration,
temperature, nature of solvent, pH, and degree of ionization. In the present studies the effect of
molecular weight of PVP on the crystallinity of the complexes was investigated.
C.3.
KINETIC STUDY OF THE TEMPLATE POLYMERISATION OF 4-VINYL
PYRROLIDONE IN THE PRESENCE OF POLY(ACRYLIC ACID) BY FT-IR
SPECTROSCOPY; EFFECT OF TEMPLATE MOLECULAR WEIGHT ON THE
RATE OF THE REACTION.
Saeed Al-Alawi and Jameela I. Al-Mutawah
Makromol. Chem. Macromol. Symp. (1991), 52: 275-282
ABSTRACT
The kinetics of template polymerisation of 4-vinylpyrrolidone in the presence of poly(acrylic
acid) was followed by FT-IR spectroscopy. It was found that the intensity of the carbonyl stretch
increased with time. The results were used to draw the rate curve for the template system by
plotting intensity of the carbonyl group band against time. It was found that the rate of
polymerisation increased as the molecular weight of PAA increased. The above results were in
agreement with the rate curve obtained by bromometric titration for the same system.
19
C.4.
EFFECT OF TEMPERATURE ON THE RATE OF POLYMERIZATION OF 4-VINYL
PYRROLIDONE IN THE PRESENCE OF POLY(ACRYLIC ACID) IN NON-AQUEOUS
MEDIUM BY FOURIER TRANSFORM INFREARED SPECTROSCOPY .
S. S. Al-Alawi
PRESENTED IN 8TH INTERNATIONAL CONFERENCE ON FOURIER TRANSFORM
SPECTROSCOPY AND PUBLISHED IN A SPIE PROCEEDING (1991), 1575 :389-90
ABSTRACT
In this investigation, the effect of temperature on the rate of polymerization of 4-vinyl
pyrrolidone (NVP) in the presence of poly(acrylic acid) (PAA) in non-aqueous medium (DMF)
was followed by Fourier Transform Infrared (FT-IR) spectroscopy. The results indicate that the
rate of polymerization of NVP increased with increasing temperature. The effect was also
investigated when NVP polymerized in presence of different molecular weights of PAA. It was
found that effect of temperature was increasing as the molecular weight of PAA increases.
C.5.
VERIFYING THE TEMPLATE EFFECT AND STUDY THE RATE OF TEMPLATE
POLYMERIZATION OF 4 VINYL PYRROLIDONE IN THE PRESENCE OF
POLY(ACRYLIC ACID) IN DMF BY VISCOSITY TECHNIQUE
Saeed S. Al-Alawi
Macromolecules (1991), 36: 2246-2249
ABSTRACT
The rate of polymerization of N-vinyl pyrrolidone (NVP) in the presence of different molecular
weight of poly(acrylic acid) (PAA) in DMF was investigated by viscosity technique. It was
found that the rate of polymerization of NVP increased as the molecular weight of PAA was
increased. The increase in the rate of polymerization was attributed to an increase in the
viscosity of the polymerization medium (template effect). The template effect verified by using
a non-reactive polymer [ poly(vinyl chloride) (PVC)] in the polymerization system just to
increase the viscosity of the medium. The results showed that the rate of polymerization
increased as the diluted solution of the low molecular weight of PVC was used.
C.6. CONFORMER SELECTION BY MONOLAYER COMPRESSION
Jamil Ahmad and K. Brian Astin
J. Am. Chem. Soc. (1986) 108:7434-7435
ABSTRACT
The ability of nerol and genraniol to form monolayers as a consequence of their amphipathic
nature has been exploited to select conformers. In the monolayers the OH group is incorporated
into the aqueous subphase and the hydrocarbon chain oriented away from it. When the
monolayer is compresses to a high surface pressure, the hydrocarbon chains are forced out into a
vertical position, while at low pressure the monolayer is in an expanded state, the hydrophobic
chains are less oriented, and the molecules lies randomly on the surface. This difference has
been used to select conformers of compressed and expanded films over dilute sulfuric acid,
using a modified Langmuir through with a Wilhemly plate balance.
20
C.7. OXIDATION OF ALCOHOL MONOLAYERS BY CHROMIC ACID
Jamil Ahmad and K. Brian Astin
Langmuir (1988) 4:780-781
ABSTRACT
Kinetics of acid dischromate oxidation of 1-phenyl-1-hexadecanol and its deuterated analogue 1[2H]-1-phenyl-1-hexadecanol have been examined at the air-water interface. A substantial
primary kinetic effect has been observed indicating rate determining C-H(D) bond breaking.
This parallelism with the bulk behaviour indicates the accesssibility of the C-H(D) bond to the
aqueous subphase.
C.8.
CORRELATION OF REDUCTION POTENTIALS OF CYANINE DYES WITH
THEIR ORBITAL ENERGIES
Jamil Ahmad and K. Brian Astin
Dyes and Pigments, (1988) 9:217-220
ABSTRACT
The relationship between the reduction potential and calculated electron affinities of some
thiacyanine dyes is examined. The results show that there is an excellent correlation between
these two parameters of the dyes.
C.9.
INFLUENCING REACTIVITY BY MONOLAYER COMPRESSION: AN ALCOHOL
DEHYDRATION
Jamil Ahmad and K. Brian Astin
J. Am. Chem. Soc., (1988) 110:8175-8178
ABSTRACT
The kinetics of the acid-catalyzed dehydration of 1,1-dipheny-1-octadecanol have been
examined at the air-liquid interface. The rate of reaction was found to be strongly dependent on
the area/molecule in the monolayer. For expanded films with large area/molecule the rate of
dehydration was over 20 times that for compressed films. The results have been interpreted in
terms of availability of the -hydrogen to the acid subphase. With highly expanded films the
hydrophobic chains are deduced to be essentiallly independent, affording facile access of the
subphase to the hydrogen. For compressed films and those of intermediate areas/molecules the
hydrophobic chains are interacting and the  - hydrogens aare oriented away from the subphase.
A threshold value of the area/molecule for -hydrogen access has been determined.
21
C.10. REACTION OF A MONOLAYER WITH SUBPHASE: DEHYDRATION OF A
SECONDARY ALCOHOL OVER SULFURIC ACID
Jamil Ahmad and K. Brian Astin
Langmuir, (1990), 6,: (6) 1098-1101
ABSTRACT
The kinetics of the acid-catalyzed dehydration of 1-phenyl-1-hexadecanol to (Z)-1-phenyl-1hexadecene have been studied on aqueous sulfuric acid-air interface for expanded (<0.1 mN m1) and compressed (mN m-1, kept constant) monolayers.
Below a threshold
area/molecule region, the initial rate of the reaction is lower than above it, but as the reaction
proceeds, affording more area/molecule, the rate increases till a stage is reached where the effect
of the reserve reaction (itself sensitive to the state of expansion) begins to outweigh this,
resulting in the novel effect of the reversal in the net direction of the reaction during its course.
For compressed film at constant surface pressure, contrived zero-order kinetics are followed, and
the reaction is dramatically slower than for the expanded state. But the surface compression
while decreasing the rate at the same time increases the yield of the reaction. This has been
explained in terms of the product molecules being removed from contact with the subphase at
high surface pressures.
C.11. REACTIONS IN MONOLAYERS : THE OXIDATION OF THIOLS TO DISULFIDES
Jamil Ahmad and K. Brian Astin
Colloids and Surfaces, (1990), 49: 281-287
ABSTRACT
The oxidation of monomolecular films of 1-octadecanethiol to diotadecyl disulfide by potassium
hexacyanoferrate (III) has been examined at the air-liquid interface. Expanded film types (i.e.,
large areas/molecule of ca 0.61 nm2/molecule) are found to react faster than the compressed
films, where the area/molecule was 0.19 nm2/molecule. This result has been ascribed to the
difficulty of orienting the octadecyl side chains in the compressed thiol film to form the
preferred skew confrontation of the disulfide product. MNDO molecular orbital calculations
have been performed on diethyl disulfide as a model system to assess the magnitude of this
preference.
C.12. SWITCHING REACTION MECHANISM BY MONOLAYER COMPRESSION :
AN ESTER HYDROLYSIS
Jamil Ahmad and K. Brian Astin
Angewandte Chemie Int. Ed. Engl. (1990),29(3):306-308
ABSTRACT
Monolayers provide a novel opportunity to examine the reactivity of molecules constrained to a
plane, where the geometrical requirements of transition states may be inferred from the reactivity
of films at varying surface pressures (or areas per molecule). The method is suitable for the
investigation of neighboring group and proximity effects.
22
C.13. REACTIONS IN MONOLAYERS : BASE-CATALYZED ESTER HYDROLYSIS
REVISITED
Jamil Ahmad and K. Brian Astin
Langmuir, 1990, 6 (12): 1797-1799
ABSTRACT
The kinetics of the base-catalyzed hydrolysis of 2-(octadecylthio)ethyl ethanoate have been
examined at the air-liquid interface. The rate of reaction was found to be independent of the
area/molecule in the monolayer, in accordance with the notion that reactions occurring at a
single center are insensitive to area/molecule variation.
C.14. WHEN FIGURES SIGNIFY NOTHING
Jamil Ahmad
Journal of Chemical Education (1991),68 (6): 469
ABSTRACT
Several examples of disregard for significant figures in everyday life are given. It is suggested
that these same examples can be the key to better education when used to add humour to the
instruction.
C.15. CLEAVAGE PATTERNS IN A LAYER OF TALC SPREAD OVER WATER
SURFACE
Jamil Ahmad
Journal of Chemical Education (1992), 69,(12): 1029
ABSTRACT
An experiment is described to demonstrate the effect of a spreading monolayer of oleic acid on a
layer of talc spread over water. The layer of talc is fractured forming star-shaped patterns on the
surface.
C.16. DIFFERENTIAL SCANNING CALORIMETRY STUDIES ON UREACARBOXYLIC ACID INCLUSION COMPLEXES
Jamil Ahmad, Allan J. Freestone and Ali Hussain
Journal of Inclusion Phenomena and Molecular Recognition in Chemistry, (1994), 18: 115121
ABSTRACT
Inclusion complexes of urea with several long chain fatty acids (of up to 30 C atoms) were
prepared and their thermal behavior was investigated by differential scanning calorimetry (DSC).
The host-guest ratios in these complexes were determined by titration against standard NaOH
23
solution using pH to determine the end point. The DSC thermograms showed that complexes of
the higher saturated acids (with 23 or more C atoms) are stable even above the melting point of
urea. This is contrary to the currently accepted view that for complexes of urea and fatty acids,
the outer urea lattice simply melts when the melting point of urea is reached, causing the
complex to decompose.
C.17. SUSPENSION OF DROPS OF A LIQUID IN A COLUMN OF WATER
Jamil Ahmad
Journal of Chemical Education (1995), 72: 178
ABSTRACTS
If a drop of a liquid is introduced into a column of another liquid with which it is immiscible, the
drop either sinks to the bottom or rises to the surface depending on the relative densities of the
liquids. Only if the densities of the two liquids are exactly equal or the drop so minuscule that
the interfacial tension becomes important enough, does the drop remain suspended.
C.18. REACTIONS IN MONOLAYERS : OXIDATION OF 1-OCTADECANETHIOL
CATALYZED BY OCTADECYLAMINE
Jamil Ahmad
Langmuir, (1996), 12: 963-965
ABSTRACT
The oxidation of monolayers of 1-octadecanethiol to dioctadecyl disulfide over a subphase of
potassium hexacyanoferrate (III) was investigated. The reaction was accelerated by the presence
in the monolayer of even a minute amount of octadecylamine, which acted as a catalyst. As the
amount of amine in the monolayer was increased, the rate of the reaction increased. A stage was
reached at which a further increase in the catalyst concentration did not cause a commensurate
increase in the rate. This has been interpreted as indicating a clumping of amine molecules in
the monolayers at higher concentrations. The reaction is also catalyzed by OH- contained in the
subphase. Over both acidic and basic solutions, however, the effectiveness of the amine as a
catalyst is reduced compared to its effectiveness over the neutral subphase.
C.19. TRACE METAL ANALYSIS OF SEWAGE SLUDGE AND SOILS IN BAHRAIN
M. Salim Akhter
Water, Air, and Soil Pollution (1990), 51: 147-152
Trace metals such as Pb, Zn, Cu, Ni, Cd and Fe were determined in sewage sludge produced at a
sewage treatment plant in Bahrain (Tubli) and soils. The soils, both untreated and treated with
the sludge, are used for agricultural purposes in Bahrain. The Trace-metals level showed the
following range (g g-1
dry weight); Pb, 242 to 609; Zn, 704 to 836, Cu, 329 to 512; Ni, 23 to 41; Cd, 1.8 to 3.9 and Fe,
1867 to 4284. The data show the degree to which untreated soils have already been
contaminated with trace elements. The level of trace-elements found in sludge showed the
following range (g g-1 dry weight); Pb, 140 to 186; Zn, 597 to 836; Cu, 348 to 449; Ni, 47 to
53; Cd, 5.7 to 9.2 and Fe, 5950 to 8520. Mean levels were generally close or lower than mean
concentration reported in the United Kingdom and the United States for sludge. They were also
24
lower than the suggested concentration limits for application of sludge on agricultural land,
which is one of the most cost effective and attractive techniques for sludge disposal. Soils
treated with this sludge (after 1 yr) were also analyzed and showed substantial enhancement of
the available level of trace elements in the soil. This eventually will lead to an increase in the
trace-element level in plants grown for human or animal consumption. This could have
phytotoxic effects, and the possibility of toxic effects on live-stocks and human beings.
C.20. ASSESSMENT OF LEAD IN ROADSIDE VEGETATION IN BAHRAIN
Ismail M. Madany*, S. Mahmood Ali and M. Salim Akhter (* Arabian Gulf University, Adliya,
Bahrain).
Environment International, (1990), 16,: 123-126
ABSTRACT
Leaves from five species of trees were sampled at 18 locations in Bahrain and were analyzed for
lead. Lead levels in leaves from areas with high traffic density were generally higher than lead
levels in leaves from areas with low traffic density. The lead levels found in this study are in the
range of 9g/g to 420 g/g, which is low compared to values reported for leaves of trees along
busy roads in developed countries. However, the concentration of lead is increasing because of
the extreme meteorological situation in Bahrain and the heavy traffic coming from other Gulf
countries across King Fahad Causeway between Saudi Arabia and Bahrain.
C.21. ASSESSMENT OF THE CHEMICAL AND PHYSICAL PROPERTIES OF ADHARI
SPRING IN BAHRAIN
Ismail M. Madany*,(*Arabian Gulf University, Adliya, Bahrain). M. Salim Akhter
Environmental International (1990) 16:297-300
ABSTRACT
Water quality for Adari Spring in Bahrain has been investigated from November 1986 to
November 1987. A total of 24 chemical and physical parameters including pH, electric
conductivity, alkalinity, acidity, hardness, calcium, magnesium, sodium, potassium, sulphate,
chloride nitrate, phosphate, flouride, iron, manganese, and total dissolved solids were analysed.
Parameters such as chloride sodium sulphate, total dissolved solids and hardness which range
from 1721 - 2724 mg/L, 810 - 1240 mg/L, 500 - 514 mg/L, 4270 - 6300 mg/L, and 1030 1650 mg/L, respectively, indicate that water is unacceptable for domestic purposes. This study
indicates ground water quality in the Adari Spring area and illustrates the need for monitoring
and maintaing the quality of ground water in Bahrain.
C.22. CHARACTERIZATION AND CONTROL OF DOMESTIC WASTEWATER IN
BAHRAIN: ASSESSMENT OF POSSIBLE APPLICATIONS
M. Salim Akhter and Ismail M. Madany* (* Arabian Gulf University, Adliya, Bahrain).
J. Environ. Sci. Health, (1991), A26(6)L: 971-979
ABSTRACT
Scarcity of fresh water in Bahrain necessitates the use of alternative sources of water. One of the
potential sources which can be utilized efficiently is domestic wastewater. Chemical, physical,
and biological characteristics of raw wastewater and secondary and tertiary effluents from the
25
Tubli sewage treatment plant in Bahrain were analyzed for a period of two years. The data show
that the tertiary effluent can be utilized for various purposes such as agriculture, groundwater
recharge, and industrial and landscape needs. For agricultural purposes, this water can be used
for only salt-tolerant crops due to its high salinity. Recharge of effluent to groundwater would
have several benefits including improving the quality of the effluent and the quality and quantity
of ground water. Moreover, it is evident from our bacteriological assessment of the tertiary
effluent that this effluent is practically free from fecal coliforms. Consideration should be given
to possible future utilization of the tertiary effluent as a source of raw water for desalinization
plants in Bahrain.
C.23. CHEMICAL ANALYSIS OF IRRIGATION WATERS IN BAHRAIN
Mohammad Salim Akhter
Wat.Sci. Tech. (1991),Kyoto,23:2159-2164
ABSTRACT
Water quality and suitability of spring water, with special emphases on Adari Spring, for
agricultural purposes in Bahrain has been investigated. A total of 24 chemical and physical
parameters including pH, electrical conductivity, alkalinity, acidity, hardness, calcium,
magnesium, sodium, potassium, sulphate, chloride, nitrate, phosphate, fluoride, iron, manganese,
total dissolved solids, were analyzed. The data show that this water is chemically unacceptable
for drinking purpose. However the water could be used for agricultural purposes, particularly for
dates plantations which can tolerate high salinity water. This study also indicates that the
ground water quality in this spring has to be monitored.
Treated sewage water was also analyzed for above mentioned parameters. The date show
promising results for agricultural purposes.
C.24. STUDIES OF THE STRUCTURES AND REACTIVITY OF SOOT
D. M. Smith, M. S. Akhter, J.A Jassim, C. A. Sergides, W.F. Welch, and A. R. Chughtai
Aerosol Science and Technology (1989)10:311-325
ABSTRACT
Vibrational spectroscopy, supplement with other techniques, is providing a comprehensive
picture of the structure and reactivity of soot. Reactions such as soot - NO2/N2O4, soot-O3, and
soot - SO2, at atmospheric and subatomspheric pressures and at different temperatures, have
been studied Determination of the kinetics and mechanisms of the formation of CO and CO2
during the soot - O3 reaction, and the effect of temperatures and the concentrations of soot and
ozone on this reaction, have led to further insights about the soot structure. Examination of the
identity and role of linkages bonding carbon layers together is underway. Application of the
Elovich equation to determine initial rates for the formation of surface species in these reactions
indicates that the soot-O3 reaction is faster than the rapid soot-NO2/N2O4 reaction which, in
turn, is faster than that of soot-SO2. Oxidation of SO2 to ionic sulfate, confirmed by isotopic
substitution, occurs in the presence of soot, water vapor, and oxygen. The presence of
stimulated solar radiation results in the formation of both ionic and covalent sulfate species. The
substrate, whether it is carbon black, cab-o-sil, or the glass walls of the reaction vessel, seems to
play role in the non photochemical oxidation of SO2 to sulfate. The miscibilities of the reaction
products of soot-O3, soot-NO2/N2O4, soot - SO2, with water vary greatly and have implications
for the depletion of tropospheric ozone in the presence of soot-containing particulates.
26
C.25. A SPECTROSCOPIC STUDY OF GASEOUS PRODUCT OF SOOT-OXIDE OF
NITROGEN/WATER REACTIONS
A. R. Chughta*l, W. F. Welch, JR*., M.S. Akhter and D. M. Smith* (*- Department of Chemistry,
University of Denver, Denver, Colorado - 80208).
Applied Spectroscopy, (1990)44(2): 294-298
ABSTRACT
The simultaneous evolution of CO, CO2, N2O and NO,detected and estimated by both infrared
spectroscopy and chemiluminesence during the reaction of soot and NO2/N2O over a range of
temperatures, suggests that, in addition to the previously described chemisorption reaction.
There is also a redox process occurring in the initial stages of the reaction. Estimations of these
gasses suggest that the redox reaction also includes reactive components other than the olefinic
segment of soot, and occurs under all conditions examined. Infrared studies show that gaseous
NO, produced immediately on the introduction of NO2/N2O4 into a reactor containing soot and
water vapor, subsequently decreases with the accompanying formation N2O.
C.26. SPECTROSCOPIC STUDIES OF OXIDIZED SOOTS
M.S. Akhter, A.R. Chughtai*, and D. M. Smith* (* Department of Chemistry, Univeristy of
Denver, Denver, Colorado 80208, USA.)
Applied Spectroscopy, (1991), 45,(4): 653-665
ABSTRACT
Vibrational spectroscopy, ESCA, and C-13 CP/MAS NMR provide a detailed picture of the
structure, and therefore reactivity, of the products of the reactions of soot with various oxidants.
Reactions such as soot NO2/N2O4, soot-O3, and soot-SO2, at atmospheric and sub-atmospheric
pressures, and at different temperatures, have been studied. The reaction between NO2/N2O4,
and n-hexane soot is rapid near room temperature, yielding several surface species, including CNO2, C-ONO, and C-N-NO2. These functionalities have been confirmed through reaction with
15NO2 and N-18O2 . The oxidation of SO2 in soot -SO2 systems yields ionic sulfate,
conformed by isotopic substitution, and requires the presence of water vapor and oxygen. The
presence of simulated solar radiation in the same system results in the formation of both ionic
and covalent sulfate species. The spectroscopic measurements show carboxyl surface species
formed during the soot-ozone reaction. The use of FT-IR, ESCA, and C-13 CP/MAS NMR has
yielded consistent results for these carbonaceous particulates in each reaction, but the vibrational
spectroscopy is easily the most definitive with such systems.
C.27. LEAD LEVELS IN SOME EYE COSMETICS USED IN BAHRAIN
Ismail M. Madany* and M. Salim Akhter (*Arabian Gulf University, P.O.Box 26671, Adliya,
Bahrain).
J. Environ. Sci. Health, (1992), A27(6): 1541-1547
ABSTRACT
27
This paper presents an analysis of lead in some surma, khol and other eye cosmetics used mainly
for young children in Bahrain. The concentration of lead ranged for 0.07 to 156 mg/g and
averaged 18.5 mg/g. Grey samples were found to have higher levels than black ones. Although
these concentrations were significantly lower than those reported in the literature, they are
nevertheless hazardous and should be taken seriously by health authorities. Our findings and
recommendations are reported to prevent further poisoning of children through the use of these
products. This problem is also found in India, Pakistan, and Kuwait as well as in the Asian
communities in European countries, such as the United Kingdom.
C.28. HEAVY METALS IN STREET AND HOUSE DUST IN BAHRAIN
M. Salim Akhter and Ismail M. Madany*(*Arabian Gulf University, P.O.Box 26671, Adliya,
Bahrain).
Water, Air, and Soil Pollution (1993), 66:111-119
ABSTRACT
A total of 106 street and household dusts have been sampled throughout Bahrain and analyzed
for Pb, Zn, Cd, Ni and Cr using the atomic absorption spectrophotometric method. The
sampling sites were divided into seven categories, including the control site. Results showed
that dust samples contained significant levels of the metals studied compared with the control
values. The mean values for Pb, Zn, Cd, Ni and Cr in street dust were 697.2, 151.8, 72.0, 125.6
and 144.4 g g-1respectively, whereas for household dust they were 360.0, 64.4, 37.0, 110.2 and
144.7 g g-1.These values suggest that motor vehicles form a major source of these metals in
dust samples. The values of heavy metals in dust samples in this study were compared with
values found in other investigations in various countries. With respect to Ni, elevated
concentration could be attributed to smoke from the burning of Kuwait oil fields. Also
correlations between metal levels in dust samples for all the metals were investigated. Our
results show that heavy metal levels in various sites in Bahrain are similar, which indicate that
Bahrain can be considered as one big urban center with high population and traffic density.
C.29.
THE CORRELATIONS BETWEEN HEAVY METALS IN RESIDENTIAL INDOOR
DUST AND OUTDOOR STREET DUST IN BAHRAIN
Ismail M. Madany*, M. Salim Akhter and O. A. Al Jowder (*Arabian Gulf University, P.O.Box
26671, Adliya, Bahrain).
Environment International, (1994), 20,( 4): 483-492
ABSTRACT
The lead, zinc, cadmium, chromium, and nickel contents in both indoor house dust and outdoor
street dust from 76 sites in Bahrain were determined by ICP-ES. The results showed widespread
heavy metal contamination, especially lead, with an overall mean value in house dust for Pb, Zn,
Cd, Cr, and Ni of 517, 202, 1.9, 11, and 10, respectively. The mean values in street dust were
742, 67, 1.5, 9.6, and 12 mg/kg, respectively. The major source of metals in street dust was
automobile exhaust. The major source of heavy metals indoors was also from automobile dust,
i.e., lead and nickel. With respect to zinc, cadmium, and chromium, indoor sources were more
important than outdoor sources. The distribution of lead both indoors and outdoors in Bahrain
showed high levels of contamination occurring generally in the north and northeastern part
where traffic is concentrated. The levels of these toxic metals found in indoor house dust may
be a significant source of exposure, especially for children.
28
C.30. MICELLE FORMATION IN MOLTEN ACETAMIDE
M. S. Akhter, S. M. Alawi, A. N. Bose
Colloids and Surfaces, A: Physicochemical and Engineering Aspects (1995), 94: 173-176
ABSTRACT
The electrical conductivity of four surfactants, sodium caprylate, sodium laurate, sodium
palmitate and sodium stearate in molten acetamide has been determined at 90oC. Conductivity
measurements show that micelles are formed in acetamide solution. Critical micelle
concentration (CMC) has been determined for each of the surfactants. It is suggested that the
simplest formula of the ionic micelle is (S-)n(CH3CONH2)x. At higher concentration the
micelle may be of the forms (NaS)m(S-)n(CH3CONH2)x where NaS denotes sodium stearate.
C.31. STUDIES ON MICELLE FORMATION AND ENTHALPY OF MICELLIZATION IN
MOLTEN ACETAMIDE
M. Salim Akhter
Colloids and Surfaces, A: Physicochemical and Engineering Aspects (1995), 99,:
255-258
ABSTRACT
The electrical conductivity of lithium dodecylsulfate, sodium dodecylsulfaate, sodium oleate and
sodium stearate has been determined in molten acetamide at 90oC. Conductivity measurements
show that for these surfactants, micelles are formed in molten acetamide solutions. The critical
micelle concentration (CMC) of each surfactant has been calculated. Lithium dodecylsulfate has
a lower CMC than sodium dodecylsulfate. Sodium oleate, which contains a double bond and
has the same number of carbon atoms as sodium stearate, has a lower CMC. The enthalpy of
micellization for sodium oleate in molten acetamide has been found by determining the CMC at
different temperatures. The results have been explained on the basis of solvation effect and
nature of micelles.
C.32. SPATIAL AND TEMPORAL PATTERNS IN HEAVY METALS CONCENTRATION
IN STREET DUST IN A HOT DESERT REGION
Ismail M. Madany*, M. Salim Akhter, O. A. Al Jowder and E. Raveendran**
(*Arabian Gulf University, P.O.Box 26671, Bahrain) (**EPC, P.O. 26909, Bahrain)
International Journal of Environmental Health Research, (1996) 6,: 93-101
ABSTRACT
This investigation reports temporal and spatial variations in heavy metal concentration in street
dusts in the State of Bahrain. Monitoring sites were chosen to include an urban area with high
traffic density, commercial, industrial, and remote areas. The overall mean levels for Pb, Zn,
Ni, Cu and ýCd were 395, 80,40,20 and 1.5 mg kg-1, respectively. The general pattern of
occurrence in order of decreasing concentration was Pb>Zn>Ni>Cu>Cd. The highest levels of
Pb, Zn and Cu were found in the high traffic density area, and strong positive correlations were
29
found between these metals, suggesting that automobiles exhaust are the dominant source of
these metals. The results did not reveal statistically significant differences on the levels of Pb,
Zn and Cu between months. Summer average values for Pb, Zn and Cu exceeded corresponding
winter values. In cold regions opposite patterns were observed. In general Ni and Cd followed
different patterns than that reported for Pb, Zn and Cu. Our results reveal relatively widespread
contamination of heavy metals, and that all sites studied were statistically not different from each
other, except a high traffic density site, indicating that Bahrain can be considered as one big
urban center.
C.33. STUDIES ON BACTERIAL ACTIVITY OF COBALT (III) COMPLEXES PART 1.
COBALT (III) AMINE COMPLEXES
Ahmed Y. Ali Mohamed and Faeza M. Al-Khedri
Transition Met. Chem., (1988), 13:434-436
ABSTRACT
Cobalt (III) complexes of the type [Co(en)2Chel]X (where en=ethylendiamine; chel = (ox) =
oxalato anion, X=Cl-, Br- and I-; Chel = CO32-, X = Cl-, Br-, I- and NO-3 ) and (+)
K[Co(edta)]. 2H2O (where edta = ethylenediaminetetracetato anion) have been investigated for
their bacterial activity against Escherichia coli B using well-cultured techniques on EMB plates
and in minimal glucose media. It appears that their activities decreases in this order :
[Co(en)2CO3] 1> [[Co(en)2(ox)]1>[Co(en)2(ox)]Cl.H2O>
k(-)[Co(edta)].2H2O>[Co(en)2CO3]NO3.2H2O>[Co(en)2CO3]Cl>
[Co(en)2(ox)]Br.H2O>[Co(en)2CO3]Br.
C.34. STUDIES ON THE BACTERIAL ACTIVITY OF COBALT(III) COMPLEXES. PART
I. COBALT (III) AMINE COMPLEXES
Ahmed Y. Ali-Mohamed and Faeza M. Al-Khedri
Transition Met. Chem., (1989), 13: 434-436
ABSTRACTS
Cobalt (III) complexes of the type [Co(en)2 Chel]X [en = ethylenediamine; Chel = (ox) =
oxalato anion, X = Cl-, Br- and I- ; Chel = CO32-, X = Cl-, Br-, I- and NO3-] and (+) K [
Co(edta)]. 2H2O (edta = ethylenediaminetetracetato anion) have been investigated for their
bacterial activity against Escherichia coli B using well-cultured techniques on EMB plates and
in minimal glucose media.
Activities decrease in the order :
[Co(en)2CO3]I >[Co(en)2(ox)]I >[Co(en)2(ox)]Cl.H2O>K(-)[Co(edta)].2H2O>
[Co(en)2CO3]NO3.2H2O>[Co(en)2CO3]Cl>[Co(en)2(ox)]Br.H2O>[Co(en)2CO3]Br
C.35. STUDIES ON THE BACTERIAL ACTIVITY OF COBALT (III) COMPLEXES.
PART II. OBALT(III) AMINOACIDATO-COMPLEXES
Ahmed Y. Ali-Mohamed and Abdulla A. R. Abdulla
Transition Met. Chem., (1989) 14: 181-184
30
ABSTRACT
Cobalt(III) complexes of the type trans- [Co(AA)2(ox)] (where AA = aminoacidato, gly =
glycinato, sar = sarcosinato, DL-ala = DL-alaninato; ox = oxalate); [Co(L-val)2 CO3] and DL[Co(en)2sar] I2 where L-val = L-valinato, en = ethylenediamine) have been investigated for their
ba2cterial activity against Escherichia coli B using well-cultured techniques on EMB agar and in
minimal glucose media. The activities decrease in the order: trans-(N) (+) K[Co(sar)2(ox)]>
trans-(N)(+)K[Co(L-ala)2 (ox)]> trans-(N)(-) K[Co (gly)2(ox)]> trans-(N) (+) K [Co(DL-ala)2
(ox)] > trans-(N) (+) K [Co(gly)2 (ox)]> trans (+) K [Co(DL-ala)2 (ox)] trans-K[Co(Lval)2CO3].
C.36.
COORDINATION COMPOUNDS AND MICRO-ORGANISMS. PART 11. INHIBITION
OF BACTERIAL GROWTH BY SOME WERNER COMPLEX ANIONS OF COBALT
(III)
Ahmed Y. Ali-Mohamed, R. D. Gillard* and D. E. Hughes**
(*School of Chemistry and Applied Chemistry, University of Wales College of Cardiff, P.O. Box
912, Cardiff CF1 3TB, U.K)
(**Dept of Microbiology, University College, P.O. Box 78, Cardiff CF1 1XL, U.K)
Transition Met. Chem., (1989), 14: 185-189
ABSTRACT
The growth of strains of E.coli is inhibited in the early stages by several complexes anions of
cobalt(III). All of these contain chelating (chel) dicarboxylate ligands (propane -1, 3-dioate,
ethane-1,2-dioate or carbonate) e.g. K3[ Co(mal)3] 3H2O where mal denotes the dianion of
propane-1, 3-dioic acid, but most of them also contain unidentate pyridines, e.g. K[Co(chel)2(Rpy)2] nH2O. Among the most active are cis and trans- K[Co (mal)2(py)2] hydrates. The
effects are distinct from those known for compounds of platinum, e.g. cis- [Pt(NH3)2 Cl2] and
rhodium, e.g. trans- [Rh(C5H5N)4Cl2] Cl.6H2O.
C.37. COORDINATION COMPOUNDS AND MICROORGANISMS, PART 12.
RHODIUM COMPOUNDS OF S-NICOTINE AND THEIR BACTERIAL ACTIVITY
Robert D. Gillard*, Julio D. Pedrosa de Jesus** and Ahmed Y. A. Mohamed
*School of Chemistry and Applied Chemistry, University of Wales Colleges of Cardiff, P.O.Box
912, Cardiff C F I 3 TB, UK.
**Department of Chemistry, University of Aveiro, 3800 Aveiro, Portugal.
Transition Met. Chem., (1989), 14: 258-260
ABSTRACT
The activities of the nicotine complexes of rhodium (III) - [RhCl3(nicH+)3](PF6)3 and trans[RhCl2(nic)4](PF6) (nicH+ = monoprotonated S-nicotine, nic = unprotonated S-nicotine) - were
studied on Escherichia coli B growing in a minimal glucose medium in both lag- and log phases.
[RhCl3(nicH+)3] (PF6)3 at 50 ppm caused bacteriostasis, and at 100 ppm or more was
bactericidal, whereas trans-[RhCl2(nic)4](PF6) at 50 ppm or more was bactericidal in the lagphase. However [RhCl3(nicH+)3] (PF6)3 delayed cell division of Escherichia coli B just
entering the log phase by two generation times, whereby the bacteria transformed from the
normal unicellular shape to filamentous forms. Cytotoxicities are reported.
31
C.38. POTENTIOMETRIC DETERMINATION OF FLUORIDE AND IODIDE IN
NATURAL AND PROCESSED WATERS OF BAHRAIN USING ION-SELECTIVE
ELECTRODES
Ahmed Y. Ali-Mohamed and Sadiq G. A. Jamali
Water Research, (1989), 23,( 5):659-662
ABSTRACT
To assess the natural availability of fluoride and iodide in Bahrain, natural and processed waters
which included ground water, tap waters, Adari Lake water and streams and waters from reverse
osmosis (RO), ion-exchange (IE), multistage flash desalination (MSF) and solar desalination
(SD) plants, in addition to blended waters, were monitored for 3 months (Oct.-Dec. 1985). The
fluoride ion concentration ranges from 0.45 to 1.51 + 0.26 mg dm-3 in natural waters; 0.003 to
0.33 + 0.016 mg -3 in the processed waters and 0.15 to 0.24 + 0.095 mg dm-3 in the blended
waters . As for the iodide ion, concentration ranges from 0.02 to 1.08 + 0.07 mg dm-3 in natural
waters; 0.01 to 0.02 + 0.002 mg dm-3 in both processed and blended water.
C.39.
BACTERIAL ACTIVITY OF COBALT(III) COMPLEXES. PART
DIETHYLENETRIAMINEMONOACETATOCOBALT(III) COMPLEXES
Ahmed Y. Ali-Mohamed
Transition Met. Chem., (1991), 16: 14-17
IV:
ABSTRACT
The activities of the diethylenetriaminemonoacetatocobalt (III) complexes, [Co(en)(DTMA)]I2,
[CoX2-(DTMA)] and [CoCO3(DTMA)]. H2O (DýTMA = diethylenetriaminemonoacetato or
formally 3-amino-3, 6-diazaoctanato; en = ethylenediamine, X = Cl-, NO2-, NCS-) were studied
on Escherichia coli B growing in a minimal glucose medium in both lag- and log phases.
Activities decrease in the order : [Co(NCS)2(DTMA)]> [Co(NO2)2(DTMA)]>
[Co(en)(DTMA)]I2 > [CoCl2- (DTMA)] > [CoCO3 (DTMA)]. H2O. The antagonistic activities
of the complexes were also studied.
C.40. ESTIMATION OF INORGANIC PARTICULATE MATTER IN THE ATMOSPHERE
OF ISA TOWN, BAHRAIN, BY DRY DEPOSITION
Ahmed Y. Ali-Mohamed
Atmospheric Environment Part B: Urban Atmosphere, (1991), 25B,( 3): 397-405
ABSTRACT
Inorganic particulate matter was sampled weekly during the period April 1985- April 1986 in Isa
Town, Bahrain. The mean annual conductivity of water-soluble inorganic particulate matter was
59.99 Scm-1; pH 7.5; total suspended solid 0.06 gdm-3; total dissolved solid 63.79 ppm; total
hardness as MgCO3 86.80 ppm; as CaCO3 208.05 ppm; Cl- 111.27 ppm; Na+ 2.18 ppm; and
NO3- 0.006 M. Each shows seasonal variations in concentration. The average aerosols maxima
32
were recorded in summer. The total suspended solid (TSS) mode of aerosol displays some
change, with a mean in winter of 0.039 gdm-3 and a mean value in summer of 0.044 gdm-3.
The aerosols data were influenced differently by some atmospheric parameters such as
temperature, humidity, wind speed and direction.
C.41. STUDIES ON THE BACTERIAL ACTIVITY OF COBALT(III) COMPLEXES. PART
III.COBALT (III) CARBOXYLATE COMPLEXES
Ahmed Y. Ali-Mohamed
J. Coord. Chem. (1993), 29: 233-246
ABSTRACT
Cobalt(III) complexes of the type [Co(en)2 (chel)] X.nH2O where en = ethylenediamine,chel =
phthalato =C6H4(CO2)22-, maleato = (O2 CCH = CHCO )2-, succinato =
2
(O2CCH2CH2CO2)2-, homophthalato = (O2CC6H4(CH2)CO2)2-, citraconato = (O2CC(CH3)
= CHCO2)2-, itaconato = (CH2 =C(CO2) CH2CO2)2-, X=NO3-,Br-,(O2CC6H4CO2H)-,
(O2CHC = CHCO2H)-, (O2C(CH2)2CO2H)-(O2CC6H4(CH2)CO2H)-,(O2CHC= C(CH2)CO2H)-, and (O2C-CH2-C(=CH2)-CO2H)-, [Co(en)2(malonato)] X.2H2O(where malonato =
(O2CCH2CO2)2-, X = Cl-, Br-, and NO3-)and [Co(en)2CO3] Cl.2H2O have been investigated
for their bacterial activity against Escherichia coli B growing on EMB agar and in minimal
glucose media both in lag and log phases. Among the most active are where chel = phthalato
and homophthalato. The effects are distinct from those known for compounds of Pt, e.g., cis[Pt(NH3)2Cl2] and rhodium, e.g., trans-[Rh(C5H5N)4Cl2]. 6H2O. Anatagonisms are reported.
C.42. ESTIMATION OF INORGANIC PARTICULATE MATTER IN ATMOSPHERES OF
VILLAGES IN BAHRAIN, BY DRY FALL
Ahmed Y. Ali-Mohamed, Khalil E. Maki, A. Amir A. Saeed, Asma M. Abdulla and Mahdia I.
Abdulla
Atmospheric Environment (1995).,29,( 13): 1519-1529
ABSTRACT
Inorganic particulate matter was sampled weekly during the period Feb-May 1992 in Bellad AlQadim [BQ], North Sehla [NS], Tubli [T], and Marquban [MQ], during the period March-May
1992 in Ad Diraz [DZ], and Karzakkan [KZ] and from April-July 1992 in Al-Ma'amir [M]
villages, Bahrain. The average mean conductivity of water soluble inorganic particulate matter
was 140.55 S cm-1; total suspended solid 0.0684 (g dm-3); total dissolved solid 172.68(ppm),
total hardness as MgCO3 48.88(ppm); as CaCO3 51.51 (ppm); Cl- 11.82(ppm); Na+ 6.13
(ppm); K+ 1.7(ppm); alkalinity 5.35 m M; and NO3- 2.69(ppm). Each shows weekly variation in
concentration. The aerosol data were influenced differently by some atmospheric parameters
such as temperature, relative humidity, prevailing wind speed and direction.
C.43.
DETERMINATION OF INORGANIC PARTICULATES: (CATIONIC, ANIONIC AND
HEAVY METALS) IN THE ATMOSPHERE OF SOME AREAS IN BAHRAIN DURING
THE GULF CRISIS IN 1991
Ahmed Y. Ali-Mohamed and Haifa A. Matter
Atmospheric Environment (1996)., 30, (20): 3497-3503
ABSTRACT
33
Inorganic particulate matter was sampled weekly during the period March-May, 1991 at different
sites at height of ~6-9m above the ground level. Deposited aerosols were chemically analysed
and a comparison was made between these sites. The percentage of tarry matter deposited on the
airborne particulate matter was found to be 40 % during the Gulf crisis compared to 5 % prior to
Gulf War (1985/86). Heavy metal analysis are also reported. The results were influenced
differently by some atmospheric parameters such as temperature, humidity, rainfall, pressure and
wind speed/direction.
C.44. CHEMICAL CONSTITUENTS OF SOME MEDICAL PLANTS GROWING IN
BAHRAIN
F. S. Al-Saleh, H. H. Ali, M. Mirza
Fitoterapia (1993), LXIV,( 3): 251 - 256
ABSTRACT
Fifty medicinal plants from over three hundred species which grow in Bahrain have been
screened for their chemical constituents. This study summarizes the detection of natural
products such as alkaloids, anthraquinones, coumarins, flavonoids, terpenes/sterols, saponins
and tannins.
C.45. LEVELS OF TRIHALOMETHANES IN THE BLENDED WATER OF
BAHRAIN
Fowzia S. Al-Saleh, Ameera S. Al-Haddad
The Science of the Total Environment (1994), 152, : 221-225
ABSTRACT
The distribution of trihalomethanes in the water of the two main power stations and the 10
blending stations in Bahrain has been studied. Total trihalomethanes in the drinking water
average 2.95 g/1. Average concentrations (g/1) of individual compounds were: CHBr3, 2.17
+ 0.3; CHBr2Cl, 0.48 + 0.14; CHBrCl2, 0.30 + 0.13.
C.46. TRACE METAL CONCENTRATIONS IN THE MEDICAL PLANTS OF THE
FLORA OF BAHRAIN
F. S. Al-Saleh and S. Chudasama
Toxicological and Environmental Chemistry, (1994), 46:1-9
ABSTRACT
Trace metal concentrations of a number of medicinal plants in the flora of Bahrain, particularly
fresh edible herbs are reported. Samples were analyzed by Inductively coupled plasma (ICP). A
large portion of the plants examined contained high concentration of toxic metals and some of
them exceed the limit of toxicity. The reported data indicate a potential health hazard.
34
C.47. TRANSITION METAL COMPLEXES OF A NEW 12-MEMBERED TETRAAZA
MACROCYCLE
Fathi M.A.M. Aqra*, Shakeel A. Shah* and Rasheed M. A. Q. Jamhour*, K. S. Saddiqi, Osama
Al-Jowder and Fawzia Al-Saleh
(*Department of Chemistry, Aligarh Muslim University, Aligarh-202002, India.
Synth. React. Inorg. Met.-Org.Chem., (1994), 24(9): 1599-1612
ABSTRACT
The direct reaction of triethylenetetramine and diethyl oxalate in DMF in a 1:1 ratio results in
the formation of the 12-membered tetraazamacrocycle triethylenetetramine oxamide (L). A
condensation reaction of triethylenetetramine and dietthyl oxalate in the presence of divalent
hydrated transition metal chlorides (Mn2+, Co2+, Ni2+ and Cu2+) and ZnCl2 in absolute
methanol in a similar ratio (1:1:1) yields ionic 12-membered macrocyclic complexes. The
results show that two water molecules are bound to the central metal ion (Mn2+, Co2+, Ni2+
and Cu2+) resulting in an octahedral environment while zinc maintains a tetrahedral geometry
for being free from water. The i.r. special bands show that the two C=O groups of the oxalato
species do not participate in coordination. The slight decrease in  (C=O) suggests bonding of
the nitrogen of the amide group to the metal ion. The complexes decompose on dissolution in
DMSO.
C.48. SYNTHESIS OF SOME NEW PYRAN DERAVITES AND THEIR ANTIMICROBIAL ACTIVITY
Fowzia S. Al-Saleh and Ezzat M. Kandeel
Indian Journal of Heterocyclic Chemistry, (1994), 3: 273-276
ABSTRACT
Cyclohexanone and cyclopentanone react with benzylidene malononitrile to give dicarbonitriles
(3a-b). Cylclohexa[b] pyrans and cyclopenta[b]pyrans were obtained from the reactions of
diarylidene derivates of cyclohexanone and cyclopentanone with malononitrile and ethyl
cyanoacetate. The antimicrobial activity of these compounds has been determined.
C.49. SYNTHESIS OF POLYFUNCTIONALLY
CONDENSED PYRIDINES
F. S. Al-Saleh and E. M. Kandeel
Chem. Environ. Res. (1994), 3(3&4)
SUBSTITUTED
PYRIDINES
ABSTRACT
Polyfunctionally substituted heteroaromatics are biologically interesting class of compounds
(1,2). In previous work from our laboratories, we have reported several new approaches for the
synthesis of polyfunctionally substituted azoles and azines utilizing simple and readily available
35
AND
starting materials. The compounds prepared were needed for potential utility as biogradable
agrochemicals (3,5).
C.50. ANTIMICROBIAL ACTIVITY OF SOME HETEROCYCLIC DERIVATIVES
F.S.Al-Saleh, A. Y. Gamal El-Din and E. M. Kandeel
Microbios (1995), 82: 87-93
ABSTRACT
A group of newly synthesized heterocyclic compounds was tested for activity against Gramnegative Escherichia and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus
and bacillus subtills. An attempt was made to correlate the structure of the compounds with
their antimicrobial activity.
C.51.
ON INTRAMOLECULAR DYOTROPY: STRUCTURAL EFFECTS ON REACTION
RATES AND X - RAY CRYSTAL STRUCTURE - MOLECULAR MECHANICS
CORRELATIONS
Judith A. K. Howard, Kenneth Mackenzie and Robert E. Johnson, School of Chemistry, The
University, Bristol, BS8 ITS
K.B.Astin. Tetrahedron Letters, (1989) 30,(37):5005-5008
ABSTRACT
Differential kinetic behaviour in thermal dyotropic rearangement of compounds containing a
cyclohexa - 1,3 - diene ring as 2H donor held proximate to a variously - substituted norbornene
element as acceptor is discussed in terms of parameters derived by single crystal X-ray structure
analysis and Molecular Mechanics calculations.
C.52. PREPARATION OF TETRAKIS(T-BUTYLISOCYANIDE) AQUACOBALT
PERCHLORATE AND REACTION WITH TERTIARY PHOSPHINE LIGANDS
Clifford A.L Becker, Abdolmajid Anisi*, Gregg Myer* and Jana D. Wright*
(*Department of Chemistry, Washburn University of Topeka, Topeka, Kans. 66621, U.S.A.).
Inorganica Chimica Acta, (1986), 111:11-18
ABSTRACT
Reaction of t-butylisocyanide with Co(ClO4)2.6H2O in 4:1 molar ratio in EtOH at 0C produces
2[Co(CNCMe3)4H2O] (ClO4)2 in near quantitative yields. Ligand substitution/reduction
reactions of [Co(CNMe3)4H2O](ClO4)2 (in CH3CN) with trairylphosphines (in CH2Cl2) at 25
C are rapid and in good yield: [Co(CNCMe3)3- {P(C6H4OMe-p)3}2]ClO4,[Co(CNCMe3)3{P(C6H4Cl-p)3}2]ClO4, 2and [Co(CNCMe3)3 {P(C6H5)3}2]ClO4 were prepared. Analogous
reaction with As(C6H5)3 caused intense color change, but only unsubstituted
{Co(CNýCMe3)4H2O] (ClO4)2 was recovered Reaction of [Co(CNCMe3)4H2O](ClO4)2 with
trialkylphosphines
produced
[Co(CNCMe3)3-{P(C6H13-n)3}2]ClO4,
[Co(CNýCMe3)3{P(CH2CH2CN)3}2ClO4, and [Co(CNCMe3)3{P(NMe2)3}2]ClO4, but
36
(II)
anticipated monosubstituted product with P(NEt2)3 was not recovered. Infrared, 1H NMR and
electronic spectra give some indication of coordination structure.
C.53.
PREPARATION OF TETRAKIS (ARYLISOCYANIDE) TRIALKYLPHOSPHITE
COBALT (I) COMPLEXES WITH STERICALLY-HINDERED ARYLISOCYANIDES
Clifford A. L. Becker, William D. Singe*r and Eric M. Tower*
(*Department of Chemistry, Washburn University of Topeka, Topeka, Kans.66621, U.S.A.)
Inorganica Chimica Acta, (1986) 113:75-79
ABSTRACT
The complexes, [Co(CNC6H3Et2-2,6)4P(OR')3]X, X = BF4, ClO4; R' = Me, Et, CHMe2; are
prepared by trialkylphosphite substitution reaction in [Co(CNC6H3Et2-2,6)5]X. The
[Co(CNC6H3Me2-2,6)3-{P(OCHMe2)3}2]ClO4 is prepared, and P(OSiMe3)3 fails to
substitute, under analogous reaction conditions. Ease of disubstitution, in preference to
monosubstitution, appears to be controlled by steric hindrance of the aryliso -cyanide, with 2,6Et2C6H3-NC<<2,4,6-Me3C6H2NC < 2,6-Me2C6H3NC<< o-MeC6H5NC< C6H5NC ; and
apparent trialkylphosphite reactivity, P(OSiMe3)3 << P(OCHMe2)3 < P(OEt)3 < P(OMe)3 ;
but monosubstituted complexes, in general, are conveniently prepared only from [Co(CNC6H3
Et2-2,6)5]X. Melting ý(decomposition) ranges, (-NC), and electronic spectra of the new
complexes are discussed, herein. Trends seem to parallel those previously observed for
triarylphosphine-substituted arylisocyanide-cobalt(I) complexes.
C.54. PREPARATION OF TETRAKIS (2,6-DIMETHYLPHENYLISOCYANIDE) COBALT
(II) PERCHLORATE IN NOVEL REACTIONS
Clifford A. L Becker and John C. Cooper* (*Chemistry Division, Naval Research Laboratory,
Washington, DC 20375-5000, U.S.A).
Inorganica Chimica Acta, (1989) 158: 141-149
ABSTRACT
Paramagnetic
tetrakis
(2,6-dimethylphenylisocyanide)cobalt(II)
perchlorate,
[Co(CNR)4]ClO4)2,
R = 2,6-Me2C6H3, has been prepared from pentakis(2,6dimethylphenylisocyanide)cobalt(II) perchlorate hemihydrate, [Co(CNR)5](ClO4)2.O.5H2O, in
novel reactions with triphenylarsine and triphenylstibine.
Analogous reaction with
[Co(CNR)5](BF4)2. 0.5H2O produced only [Co(CNR)5]BF4. Both [Co(CNR)5] X2.0.5H2O, X
= ClO4-, BF4-, can be recrystallized from CH2Cl2, CHCl3 or CH2ClCH2Cl in 0.15 - 0.30 M
initial concentration, to produce [Co(CNR)5] X2.S (S = adducted solvent) in good yield.
Recrystallization of [Co(CNR)5](ClO4)2.0.5H2O from dilute (CM < 5 X 10-3 M) solution,
however, produces [Co(CNR)4](ClO4)2. S, while [Co(CNR)5](BF4)2.S, while
[Co(CNR)5](BF4)2. 0.5H2O regenerates the starting material. Recrystalizations from CH3CN
or CH3NO2 produce [Co(CNR)5](ClO4)2. 0.5H2O (concentrated solution) or no recovered
product (dilute solution). Solid-state properties of magnetic susceptibilities, diffuse reflectance
electronic spectra, and mull-infrared are investigated. Distorted square planar coordination of
RNC in [Co(CNR)4](ClO4)2 is suggested. Infrared (ClO4) strongly suggests monodentate
37
ClO4- coordination in [Co(CNR)4](ClO4)2 or [Co(CNR)4(ClO4)2], while the possibility of
weaker ClO4- coordination in [Co(CNR)5](ClO4)2
.).5H2O is ambiguous. Isolation of [Co(CNR)4](ClO4)2 is the first observed incident of
significant difference between BF4- and ClO4- salts of Co(II)-arylisocyanide complexes.
C.55.
REACTIONS OF DECAKIS(ISOPROPYLISOCYANIDE)DICOBALT(II)
COMPLEXES WITH TERTIARY PHOSPHINE LIGANDS
Clifford A. L. Becker, Saleh AL-Qallaf and John C. Cooper*
(*Chemistry Division, Naval Research Laboratory, Washington, DC 20375-5000 (U.S.A.)
Inorganica Chimica Acta, (1991) 188:99-106
ABSTRACT
Reaction of [Co2(CNCHMe2)10]X4. nH2O (X = ClO4, BF4) with triarylphosphines and
substituted
trialkylphosphines
produces
disubstituted
Co
(I)
complexes,
[Co(CNCHMe2)3(PR3)2]X;R = C6H5, C6H4Clp, C6H4OMe-p, CH2C6H5, NMe2,
CH2CH2CN.
These reduction/ligand-substitution reactions are analogous to those of
[Co(CNCMe3)4H2O](ClO4)2. Reaction with unsubstituted trialkylphosphines produces Co(III)
complexes, [Co(CNýCHMe2)4(PR3)2]X3, R = C4H9-n, C6H13-n; in disproportionation
reaction from which the Co(I) complex is not recovered: [Co2(CNCHMe2)10]X4 + 4PR3 
[Co(CNR)4(PR3)2]X3+ [Co(CNR)3 (PR3)2]X +3CNR. Solution properties ((-NC),
electronic spectra, ^M ) are compared for CNCHMe2 and CNCMe3 complexes. The Co(I)
complexes are 1:1 electrolytes in CH3CN, CH3NO2, CH3C(O)CH3 and CH2Cl2; the Co(III)
complexes are 3: 1 electrolytes in CH3CN and CH3NO2, but exhibit increasing ion-pairing in
acetone and CH2Cl2. The (-NC) suggest decreasing * -acceptance in the order: CNCHMe2
>> P(C6H4Cl-p)3 > P(C6H5)3> P (CH2CH2CN)3 > P(C6H4OMe-p)3 > P(CH2Ph)3 >
P(NMe2)3. Solution structure for [Co(CNCHMe2)3(PR3)2]X is believed to be distorted
trigonal bipyramidal, but rigorous D4h for [Co(CNCHMe2)4(PR3)2]X3.
C.56.
SYNTHESIS, CHARACTERIZATION AND MOLECULAR STRUCTURE OF
TETRAKIS(2,6-DIETHYLPHENYLISOCYANIDE) BIS (PERCHLORATO) COBALT
(II) . AN EXAMPLE OF DISSIMILARITY BETWEEN PERCHLORATE AND
TETRAFLUOROBORATE SALTS
Clifford A. L Becker and John C. Cooper*
(*Chemistry Division, Naval Research Laboratory, Washington, DC 20375-5000 (U.S.A)
Inorganica Chimica Acta, (1991), 182: 25-32
ABSTRACT
Reaction of 2,6-Et2C6H3NC in 5:1 mole ratio with Co(II) produces Co(CNR)5X2.H2O, R=2,6Et2C6H3; X = ClO4, BF4; but the perchlorate salt spontaneously decomposes in solid state to
Co(CNR)4(ClO4)2 . The species Co(CNR)4(ClO4)2 was determined by X-ray crystallography
to contain equivalent, monodentate, trans-coordinated perchlorate ions with average Co-O bond
length 2.266(7) A, and inequivalent arylisocyanide ligands
38
with average Co-C bond lenghts 1.896(13) and 1.887(11) A in approximately square planar
coordination (C-Co-C bond angles 87.8(4) and 92.2(4), i.e. trans-[Co(CNR)4(ClO4)2].
Inequivalency of the arylisocyanides is achieved primarily through different tilt of the phenyl
rings relative to the CoC4 plane and location of the perchlorates directly above or below one
pair of CNR. The complex crystallizes in triclinic space group P1 with a = 11.550(3), b =
13.464(3) A,  = 77.39(2),  = 68.43(2),  = 86.17(3). Final discrepancy values of R = 0.0726
(Rw = 0.0573) were obtained from 3723 unique, observed reflections. Solid state physical
properties (IR, diffuse reflectance and magnetic susceptibility) are compared for [Co(CNR)2
(ClO4)2]
and [Co(CNR)5] (BF4)2 . H2O.
Previously reported [Co(CNC6H3Me22,6)4](ClO4)2 should now be formulated as trans-[Co (CNC6H3Me2-2,6)4](ClO4)2], but the
tetrafluoroborate ions in both Co(CNC6H3Et2-2,6)5(BF4)2.H2O and Co(CNC6H3Me22,6)5(BF4)2.0.5H2O are probably ionic.
C.57.
SYNTHESIS OF TETRAKIS (CYCLOHEXYLISOCYANIDE) BIS (TRI-NHEXYLPHOSPHINE)-COBALT
(III)
PERCHLORATE
AND
TRIS
(CYCLOHEXYLISOCYANIDE) BIS (TRI-N-HEXYLPHOSPHINE) COBALT (I)
PERCHLORATE. AN EXAMPLE OF COBALT (II) DISPROPORTIONATION WITH
ALKYLISOCYANIDE AND TRIALKYLPHOSPHINE LIGANDS
Clifford A. L. Becker, M. A. Salam Biswas and John C. Cooper* (Chemistry Division, Naval
Research Laboratory, Washington, DC 20375-5000 (USA).
Inorganica Chimica Acta, (1991), 188: 191-194
ABSTRACT
Isolation of [Co(CNC6H11)3{P(C6H13-n)3}2]ClO4 and [Co(CNC6H11)4 {P(C6H13n)3}2](ClO4)3 in the reaction of [Co(CNC6H11)5](ClO4)2 with excess P(C6H13-n )3 with
excess P(C6H13-n)3 in ethanol solution establishes the disproportionation nature of this reaction
: 2[Co(CNR)5]2+ 4PR3 [Co(CNR)3(PR3)2]+ +[Co(CNR)4(PR3)2]3+ + 3 ýCNR. The
complexes are characterized by (-NC), electronic spectra, magnetic susceptibility and molar
conductivity. White, diamagnetic [Co(CNC6H11)4{P(C6H13-n)3}2] (CIO4)3 is probably a
regular tetragonal structure (D4h) in solution but distorted in the solid state, i.e. trans[Co(CNC6H11)4{P(C6H13-n)3}2(ClO4)3. Yellow, diamagnetic [Co(CNC6H11)3{P(C6H13n)3}2] ClO4 is probably distorted axially disubstituted trigonal bipyramidal (C2v) in both
solution and the solid state. Molar conductivities for [Co(CNC6H11)3 P(C6H13-n)3}2]ClO4
indicate fully-ionized 1:1 electrolyte behavior in all solvents, but ^M values for
[Co(CNC6H11)4{P(C6H13-n)3}2] (ClO4)3 suggest 3:1 electrolyte behavior in CH3CN and
CH3NO2, with increasing ion-pairing in Me2NCHO, CF3CH2OH, acetone and CH2Cl2.
C.58.
SYNTHESIS
OF
TETRAKIS
(2,6-DI-ISOPROPYLPHENYLISOCYANIDE)
BIS(PERCHLORATO)COBALT(II) AND HEXAKIS (2,6-DI-ISOPROPYL PHENYLISOCYANIDE) COBALT (II) TETRAFLUOROBORATE.
AN EXAMPLE OF
DISSIMILARITY BETWEEN PERCHLORATE AND TETRAFLUOROBORATE
SALTS.
Clifford A. L. Becker
Synth. React. Inorg. Met. - Org. Chem., (1992), 22(4): 437-446
ABSTRACT
39
Reaction of 2,6-(CHMe2) 2C6 H3NC in 5:1 mole ratio with Co (II) produces transient Co(CNR)
The perchlorate salt spontaneously transforms into
5X2.nH2O, X=ClO4, BF4.
[Co(CNR)4(ClO4)2] and the tetrafluoroborate salt into [Co (CNR)6] (BF4)2. Perchlorate-ion
coordination is confirmed by analogy with [Co(CNR)4(ClO4)2], R = 2,6-Me2C6H3, 2,6Et2C6H3. The BF4- salt is the first known example of a hexakis (organoisocyanide) cobalt (II)
complex to be isolated, and shows deviation from octahedral coordination in solid state.
C.59.
SYNTHESIS OF TRIS(ISOPROPYLISOCYANIDE) BIS (TRI-p- METHOXYPHENYLPHOSPHINE) COBALT(II)PERCHLORATE. A POSSIBLE INTERMEDIATE IN
COBALT(II) REDUCTION/LIGAND SUBSTITUTION REACTIONS
Clifford A. L. Becker
Synth. React. Inorg. Met. - Org. Chem., (1992), 22(1): 99-105
ABSTRACT
The Co(II) complex, [Co(CNCHMe2)3{P(C6H4OMe-p)3}2](ClO4)2, is reported. Reaction data
are consistent with this complex being an intermediate in reduction/ligand substitution reactions
of Co (II)-organoisocyanide complexes with tertiary phosphines. Characterization data for this
complex are consistent with trigonal bipyramidal coordination in solid and solution states.
C.60. ADDITION COMPLEXES OF TETRAKIS (t-BUTYLISOCYANIDE) COBALT(II)
PERCHLORATE WITH NITROGEN BASES
Clifford A. L. Becker
J. Coord. Chem (1992), 26: 231-236
ABSTRACT
Reaction of [Co(CNCMe3)4(H2O)](ClO4)2 with selected aromatic and cyclic aliphatic amines
and thioureas, either by dissolution or digestion, leads to complexes of the form
[Co(CNCMe3)4L2](ClO4)2.nH2O; L=C5H5N, 3-MeC5H4N, 4-MeC5H4N, C9H7N, C5H10NH, 3-MeC5H9NH, 4-MeC5H9NH, HN(CH2CH2)2O, H2NC(S)NH2, HNC(S)NHEt. Steric
hindrance decreases reactivity of the amine and stability of the complex. Characterization by IR,
diffuse reflectance electronic spectra, and magnetic susceptibility suggests tetragonal
coordination.
C.61.
REACTIONS OF ISOPROPYLISOCYANIDE AND t-BUTYLISOCYANIDE WITH
COBALT (II) PERCHLORATE AND TETRAFLUOROBORATE
Clifford A. L. Becker
J. Coord. Chem (1993), 28,: 147-153
ABSTRACT
Reaction of isopropylisocyanide with CoX2. 6H2O (X=ClO4) in EtOH produced
[Co2(CNCHMe2)10]X4.5H2O,
and
reaction
of
t-butylisocyanide,
produced
.
[Co(CNCMe3)4H2O]X2 nH2O. The complexes were characterized by IR, electronic spectra,
magnetic susceptibility, and molar conductivity. CNCHMe2 complexes are diamagnetic in the
40
solid state and one-electron paramagnetic in solution; this and other data are consistent with
dimerization in the solid and dissociation in solution. CNCMe3 complexes are one-electron
paramagnetic in the solid and solution states, this being consistent with a monomeric structure.
C.62.
SYNTHESIS OF PARAMAGNETIC TETRAKIS (BENZYLISOCYANIDE) BIS (TRI-pTOLYLARSINE OXIDE) COBALT (III) TETRAFLUOROBORATE. AN EXAMPLE
OF OXIDATION OF LIGAND AND METAL IN REACTION OF PENTAKIS
(ARYLISO -CYANIDE)COBALT(II) WITH TRIARYLARSINE
Clifford A. L. Becker
Inorganica Chimic Acta, (1993), 203: 165-178
ABSTRACT
Golden yellow, paramagnetic [Co(CNCH2Ph)4{OAs(C6H4Me-p)3}2](BF4)3, is synthesized by
reaction of [Co(CNCH2Ph)5](BF4)2 with excess As(C6H4Me-p)3 in CH2Cl2 solution. Both
AsR3 and Co(II) are apparently rapidly oxidized in this novel reaction, although Co(II)
disproportionation has not been excluded. The microcrystalline salt is characterized by IR,
electronic spectra, magnetic susceptibility and molar conductivity; stability in solution is limited.
Effective magnetic moment of 3.58 BM indicates the intermediate spin state of two unpaired
electrons, previously unobserved for Co(III). Simple crystal field rationalization suggests a
3B2g[(eg)4(b2g)1 (a1g)1] ground state, based on tetragonally elongated octrahedral coordination.
[Co2(CNCH2Ph)10](BF4)4 .H2O is synthesized as starting material and characterized; data are
consistent with Co-Co bonded dimeric structure in the solid state and [Co(CNCH2Ph)5](BF4)2
monomeric structure in solution.
C.63.
SYNTHESIS OF MONOSUBSTITUTED PENTAKIS (2,6-DIETHYL-PHENYLISO
CYANIDE)COBALT(I) COMPLEXES WITH BIDENTATE TERTIARY PHOSPHINE
LIGANDS. I. MONOMETALLIC COMPLEXES
Clifford A. L. Becker
J. Coord. Chem. (1993), 29: 73-80
ABSTRACT
Reaction of [Co(CNC6H3Et2-2,6)5]BF4 with bidentate phosphines leads to monosubstituted
Co(I)complexes, [Co(CNC6H3Et2-2,6)4(L-L)]BF4, where L-L = Ph2P(CH2)nPPH2, n = 1-4,6;
Ph2PCH2CH2AsPh2, Ph2PC6H4PPh2-p, Ph2PCH=CHPPh2-trans. Reaction conditions are
such that disubstitution would be possible, but bidentate bridging to form bimetallic complexes
is not favoured. Comparison of (-NC) IR, electronic spectra, and molar conductivities with
values for [Co(CNC6H3Et2-2,6)4L]X, where X = ClO4, BF4;L = monodentate triarylphosphine;
indicates that these new complexes must also be five-coordinate Co(I) complexes, in which the
potentially bidentate phosphine ligands are coordinated through only one P atom. Structures are
approximately trigonal bipyramidal in solution and the solid state, with the phosphine ligand
occupying an axial position.
41
C.64.
SYNTHESIS AND CHARACTERIZATION OF TETRAKIS (ALKYLISOCYANIDE)
BIS (TRIALKYLPHOSPHINE) COBALT (III) COMPLEXES
Clifford A. L. Becker and M. S. Salam Biswas
J. Coord. Chem. (1993), 29: 277-286
ABSTRACT
White cobalt(III) complexes of the form [Co(CNR)4(PR3)2]X3, X=ClO4, BF4;
CNR=CNCHMe2, CNC4H9-n, CNC6H11, CNCH2Ph; PR3= P(C6H13-n)3, P(C4H9-n)3,
P(C3H7-n)3, were synthesized by reaction of pentakis(alkylisocyanide)cobalt (IIý) with excess
trialkylphosphine. Reactions were performed on [Co2(CNR)10]X4.nH2O, R= CHMe2, CH2Ph,
dissolved in CH2Cl2, and on [Co(CNR)5]X2, R = C6H11, C4H9-n, prepared in situ in EtOH.
The Co(III) complexes were characterized by IR, diffuse reflectance electronic spectra, and
magnetic susceptibilities in the solid state, and by (-NC), electronic spectra, and molar
conductivities in solution. Structures appear to be trans-[Co(CNR)4(PR3)2]X3 in both media.
Magnetic susceptibilities are somewhat problematic in that measurement indicate lower
diamagnetism or slight paramagnetism, as compared to anticipated diamagnetic values.
C.65.
SYNTHESIS OF MONOSUBSTITUTED PENTAKIS (2,6-DIETHYL- PHENYLISO CYANIDE)COBALT(I)COMPLEXES WITH BIDENTATE TERTIARY PHOSPHINE
LIGANDS. II. BIMETALLIC COMPLEXES
Clifford A. L. Becker
J. Coord. Chem. (1993), 30: 253-259
ABSTRACT
Reaction of bidentate tertiary phosphines with excess [Co(CNR)5]BF4, or reaction of
[Co(CNR)4L-L]BF4 with excess [Co(CNR)5]BF4, leads to bimetallic complexes of the form,
[(RNC)4CoL-LCo(CNR)4](BF4)2,R=2,6-Et2C6H3, L-L = p-Ph2PC6H4PPh2, Ph2PCCýPPh2,
Me2PCH2CH2PMe2, Ph2PCH2CH2PPh2, Ph2PCH2CH2CH2PPh2. Comparison of the (-N
C) IR patterns, electronic spectra, and molar conductivity values of these bimetallic complexes
with data for other Co(I)organoisocyanide complexes indicates that the two -Co(CNR)4 moieties
are almost totally independent of each other. Recorded max values are the same as for the
[Co(CNR)4L-L]BF4 complexes, but the  values, although very large, are less than double. ^M
values in acetone, and probably also in CH2Cl2, are better interpreted as twice the normal
conductivity for 1:1 electrolytes than conductivity for 2:1 electrolytes.
C.66.
SYNTHESIS
OF
TETRAKIS(ALKYLISOCYANIDE)BIS(TRIARYLARSINE)
COBALT(II) COMPLEXES. LIGAND SUBSTITUTION WITHOUT REDUCTION IN
PENTAKIS(ALKYLISOCYANIDE)COBALT(II)
Clifford A. L. Becker
J. Coord. Chem. (1994), 31: 337-346
ABSTRACT
Reactions of excess triarylarsine with pentakis(alkysklisocyanide)cobalt(II) in EtOH or CH2Cl2
have produced complexes of the form [Co(CNR)4(AsR3)2]X2, where X = ClO4, BF4; AsR3 =
42
AsPh3, As(C6H4Me-p)3; CNR = CNC6H11, CNCHMe2, CNCH2Ph, CNC4H9-n. Magnetic
susceptibilities (eff = 1.8-2.3 BM),(-NC), and diffuse reflectance electronic spectra suggest a
tetragonal structure, trans-[Co(CNR)4(AsR3)2]X2, in the solid state. Electronic spectra, (-N
C), and molar conductivity data are compatible with tetragonal structures in CH2Cl2 and
CH3CN solutions, but may suggest cis-isomerization in CF3CH2OH solution. Reactions with
Ph2AsCH2CH2AsPh2 have
produced [Co(CNR)4(Ph2AsCH2CH2AsPh2)2]X2, CNR =
CNCHMe2, CNC6H11, CNCH2Ph; which appear to be six-coordinate, in which
Ph2AsCH2CH2AsPh2 is monodentate. [Co(CNCHMe2)4(Ph2AsCH2CH2AsPh2)2]-(ClO4)2
appears
to
be
tetragonal
in
solid
and
solution
states,
but
[Co(CNR)4((Ph2AsCH2CH2AsPh2)2]X2, R = C6H11, CH2Ph; may be the cis - isomers.
Solution decomposition leads to formation of the tetrahedral complexes, [Co(OAsR3)4]X2, R =
Ph, C6H4Me-p; X = ClO4, BF4.
C.67.
SYNTHESIS OF TETRAKIS (ISOPROPYLISOCYANIDE) BIS (1,2BIS{DIPHENY
LARSINO}
ETHANE)COBALT
(II)
PERCHLORATE.
MONODENTATE
COORDINATION BY A NORMALLY CHELATING BIDENTATE LIGAND.
Clifford A. L. Becker
Synth. React. Inorg. Met.-Org. Chem., (1994), 24(5): 855-865
ABSTRACT
The Co(II) complex, [Co(CNCHMe2)4(Ph2AsCH2CH2AsPh2)2](ClO4)2, was synthesized by
the reaction of [Co2(CNCHMe2)10](ClO4)4. 5H2O with excess Ph2AsCH2CH2AsPh2.
Characterization data in the solid state are consistent with six-coordinate, tetragonal coordination
in which the Ph2AsCH2CH2AsPh2 ligands are monodentate. This complex has limited stability
in solution.
C.68. CYCLIC VOLTAMMETRIC STUDIES OF TRIS
(TERTIARY PHOSPHINE)COBALT(I) COMPLEXES
C.A.L. Becker and K. R. Barqawi
J. Coord. Chem. (1995), 34, 273-282
(ALKYLISOCYANIDE)BIS
ABSTRACT
Synthesis and characterization of tris (alkylisocyanide) bis (triarylphosphine) cobalt(I)
complexes, [Co(CNR)3(PR3)2]ClO4, has been extended to include CNR = CNCMe3, PR3=
P(C6H4CF3-p)3, P(C6H4F-p)3, P(C6H4Me-p)3; PR3 = PPh3, CNR = CNC6H11, CNCH2Ph,
CNC4H9-n.
Reduction of [Co(CNCMe3)4H2O](ClO4)2 did not occur with PR3 =
P(C6H4NMe2-p)3 and P(C6F5)3. Solution and
solid state structures of the new
[Co(CNR)3(PR3)2]ClO4 complexes appear to be distorted disubstituted trigonal bipyramidal
examples with the phosphine ligands in axial positions, but the extent of distortion from rigorous
D3h symmetry in solution appears to vary for different complexes. Oxidation potentials, E½,
measured in CH3CN, for the oxidation of Co(I) to Co(II), are essentially independent of the
RNC ligands, remaining within the narrow range of + 0.20 to 0.25V for
[Co(CNR)3(PPh3)2]ClO4, R = CMe3, CHMe2, C6H11, CH2Ph, C4H9-n. Variation of the
tertiary phosphine ligands has a pronounced effect on the E½ values, which range from + 0.03 to
+ 0.75V, increasing steadily as PR3 (in [Co(CNCMe3)3(PR3)2]ClO4) is varied : P(NMe2)3 <
P(C4H9-n)3  P(C6H13-n)3 < P(C6H4OMe-p)3 < P(C6H4Me-p)3 < PPh3 P(CH2Ph)3 <
P(C6H4Cl-p)3  P(C6H4F-p)3 < P(CH2CH2CN)3 < P(C6H4CF3-p)3. Trends in E½ values are
43
better explained in terms of -donation than * -acceptance. The voltammograms are in general
quasi-reversible, but the highest E½ values show irreversible behaviour. It is proposed that the
Co(I) complex, with approximately trigonal bipyramidal structure in solution, is oxidized to the
Co(II) complex, [Co(CNR)3(PR3)2]2+, with a regular trigonal bipyramidal structure.
C.69.
SYNTHESIS OF TETRAKIS (2,6-DIISOPROPYLPHENYLISOCYANIDE) BIS(PYRIDINE)COBALT(II) PERCHLORATE. AN EXAMPLE OF STERIC
HINDRANCE RETARDING REDUCTION BUT ALLOWING LIGAND ADDITION
Clifford A. L. Becker and M. A. Salam Biswas
Synth. React. Inorg. Met.-Org. Chem., (1995), 25(2): 269-282
ABSTRACT
Reaction of [Co(CNR)4(ClO4)2], R = 2,6-(Me2CH)2C6H3, with excess aromatic amines
produced the addition complexes [Co(CNR)4L2](ClO4)2, L = C5H5N, 3-MeC5H4N, 4MeC5H4N. Attempted reaction of [Co(CNR)4(CIO4)2] with C5H10NH, C9H7N, and
H2NC(S)NH2 caused decomposition of the Co (II) complex. Characterization by diffuse
reflectance electronic spectra, (-NC) IR, and magnetic susceptibilities, in the solid state, is
compatible with a tetragonal structure; i.e., trans-[Co(CNR)4(ClO4)2] in C5H5N, however,
caused reduction to [Co(CNR)5]ClO4, which was also characterized. Steric hindrance by the
2,6-(Me2CH)2C6H3- moiety apparently retards reduction of Co(II) to Co(I) more effectively
than it retards ligand addition in [Co(CNR)4(ClO4)2].
C.70. REACTIONS OF PENTAKIS(ARYLISOCYANIDE)COBALT(II)
WITH TRIPHENYLARSINE AND TRIPHENYLSTIBINE
Clifford A. L. Becker
Synth. React. Inorg. Met.-Org. Chem., (1995), 25(9) : 1455-1466
PERCHLORATE
ABSTRACT
The Co(II) complex, [Co(CNC6H4Me-o)4(ClO4)2], was synthesized from [Co(CNC6H4Meo)5](CIO4)2 by reaction with AsPh3, SbPh3, and incomplete dissolution in CH2Cl2. Analogous
procedures on [Co(CNPh)5](ClO4)2.H2O failed to produce a tetrakis complex. These results
confirm that stability and ease of synthesis for the [Co(CNR)4 (ClO4)2] complexes parallel stric
hindrance of the aryl group, R = 2,6-(CHMe2)2C6H3 > 2,6-Et2C6H3 > 2,6-Me2C6H3 > oMeC6H4 > C6H5. Physical properties for [Co(CNC6H4Me-o)4(ClO4)2] and [Co(CNC6H4Meo)5ClO4 are reported; ClO4- coordination in [Co(CNC6H4Me-o)4(ClO4)2 ] is concluded
because the physical properties are so analogous to those of other known [Co(CNR)4(CIO4)2]
complexes.
C.71.
RAPID EXTRACTION AND SPECTROPHOTOMETRIC DETERMINATION OF
COBALT USING N-PHENYL BENZOHYDROXAMIC ACID AND AMMONIUM
THIOCYANATE
44
Y. K. Agrawal* and S. P. Chudasama (*Chemistry Department, School of Sciences, Gujarat
University, Ahmedabad 380 009, India)
Afinidad L, Mayo-Junio, (1993), 445: 169 - 171
ABSTRACT
A rapid method for the separation and determination of cobalt has been developed and applied to
natural water samples. The procedure is based on the extraction of cobalt with NPhenylbenzohydroxamic acid (PBHA) into chloroform at pH10. Cobalt is back extracted with
HCI, complexed with ammonium thiocyanate and the blue coloured complex extracted into
ethylacetate having maximum absorbance at 640 nm and molar absorptivity 1.7 x 103 l mol-1
cm-1 . effect of the diverse ions upon the linear relationship as conc vs absorbance for CoPBHA-SCN are investigated. The cobalt is determined in natural water samples.
C.72.
SPECTROPHOTOMETRIC DETERMINATION OF FEBENDAZOLE
Subhadra P. Chudasama
Indian J. of Pharm. Sci., (1995) 57(4): 173-175
ABSTRACT
A simple spectrophotometric method for the determination of febendazole by hydroxamic acid
formation in dosage forms is described. Febendazole reacts with hydroxylamine hydrochloride
in alkaline medium to give hydroxamic acid, which forms a reddish violet coloured complex
with Iron (III) in acidic medium having maximum absorbance at 500 nm, and molar absorptivity
of 5.0 x 103 l.mol-1 cm-1.
C.73. REVIEW OF POLLUTION STUDIES CARRIED OUT IN BAHRAIN
Ismail M. Madany, S. M. Ali, M. S. Akther and J. M. Zainal
J. Shoreline Management , (1986) ,2: 35-54
ABSTRACT
Environmental pollution in a country as small as Bahrain should be treated seriously. There are
few experimental data available about the kind and amount of gas, liquid and solid pollutants.
Most of the work done to date concentrated on theoretical surveys of some of the major
industries in Bahrain. Several studies have been reported on the impact of marine pollution on
fisheries, the effect of dredging and land reclamation operations and the problem of solid
wastes.
C.74. ASSESSMENT OF LEAD CONTAMINATION IN BAHRAIN ENVIRONMENT
1 : ANALYSIS OF HOUSEHOLD PAINT
Ismail M. Mandany, S. Mahmood Ali, and M. Salim Akhter
Environment International, (1987), 13 : 331-333
ABSTRACTS
The analysis of lead in household paint collected from various old buildings in Bahrain is
reported. Atonomic Absorption spectrophotometric method, both flame and flameless (graphite
45
furnance) techniques, were used for the analysis. The concentrations of lead in paint were found
in the range 200 to 5700 mg/kg, which are low compared to the limit of 0.5% in U.K. and 0.06%
in U.S.A. Nevertheless, these are hazardous.
Recommendations are reported in order to avoid paint containing lead.
C.75. HEAVY METALS ANALYSIS IN BAHRAIN REFINERY SLUDGE
Ismail M. Madany*, M. Salim Akhter, and S. Mahmood Ali (* Arabian Gulf University, P.O.Box
26671, Adliya, Bahrain).
Nuclear and Chemical Waste Management, (1988), 8:.165-167
ABSTRACT
The analysis of lead, zinc and cadmium in Bahrain refinery sludge collected from various
depositions sites at Bahrain petroleum company (BAPCO) are reported. Atomic Absorption
spectrophotometric method, both flame and flameless (graphite furnance) techniques, were used
for the analysis. The concentrations of lead, Zinc and cadmium were found in the range, 66.1 to
14630.9 mg/kg (0.007% to 1.46 %), 47.4 to 1791.1 mg/kg (0.005 % to 0.17%), 0.24 to 5.40
mg/kg (0.00002% to 0.0005%), respectively. These concentrations are less than 1 % as is
accepted internationally. Nevertheless, these are hazardous and should be managed properly.
46