National Journal of Chemistry, 2006, Volume 23,352-367 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء New rhenium and zinc complexes of 2-formylpyridine N(4)-phenylthiosemicarbazone Mohamad Jaber Al-Jeboori Department of Chemistry, College of Education, Ibn Al-Haitham, University of Baghdad, P.O. 4150, Adhamiyah, Baghdad, Iraq. e-mail:mohamadaljeboori@yahoo.com (NJC) (Received on 11 / 4 / 2006 ) (Accepted for publication on 19/8 / 2006 ) Abstract A New rhenium(V)-oxo, rhenium(III) and Zn(II) complexes [ReOCl2(L)], [Re(L)2]Cl and [ZnCl2(HL)](where; HL = 2-formylpyridine-N(4)phenylthiosemicarbazone) have been synthesised and characterised. [ReOCl3(PPh3)2] and [ReO4]- in presence of PPh3 have been used as a starting material to prepare rhenium(V)-oxo and rhenium(III) complexes, while ZnCl2 is used to prepare the zinc complex. The new complexes have been characterised by microanalyses, IR, (UV-Vis.), 1 H, 13C NMR, mass spectroscopy and molar conductance. These studies show the Re(III) ion is in a distorted octahedral environment with two tridentate deprotonated thiosemicarbazone binding as monoanionic ligands through the sulfur, pyridyl nitrogen and azamethinic nitrogen in which the complex does not result in isomeric mixtures. The geometry about Re(V) ion is a distorted octahedral environment with one tridentate deprotonated monoanionic ligand, two chloro ligands and oxo moiety. The NMR studies (1H, 13C) of [ReOCl2(L)] show the existence of the complex in two isomers in solution. On the other hand the geometry about Zn is a trigonal bipyramidal with one tridentate ligand in thion form, and two chloro ligands. الخالصة ) ذات الصيغ العامةII( ) و الزنكIII( ) اوكسو و رينيومV( تم تحضيرو تشخيص معقدات جديدة للرينيوم : [ على التوالي حيثZnCl2(HL)][وRe(L)2]Cl [وReOCl2(L)] [بوجود ثالثي فنيلReO4]- [ وReOCl3(PPh3)2] تم استخدام. ثايوسميكاربازون-N4فورمايل بردين-6 =HL بينما تم استخدام كلوريد الزنك كمادة, )III( ) اوكسو والرينيومV( الفوسفين كمواد اولية في تحضير معقدات الرينيوم وIR تم تشخيص المعقدات الجديدة بوساطة التحليل الدقيق للعناصر و طيف ال. اولية عند تحضير معقد الزنك بينت هذه. و طيف الكتلة و التوصيلية الموالرية1H, 13C و طيف الرنين النووي المغناطيسيUV-Vis طيف ال 352 National Journal of Chemistry, 2006, Volume 23,352-367 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء ) هو ثماني السطوح المشوه حيث تتناسق جزيئتان من اللكيندIII( الدراسات ان الشكل الفراغي حول ايون الرينيوم ثالثية االرتباط بشكل انيوني من خالل ذرة الكبريت و نتروجين مجموعة البريدايل و نتروجين مجموعة االيزوميثانيك ) شكل ثماني السطوح المشوه من خاللV( كذلك يظهر معقد الرينيوم. حيث يظهر المعقد ايزومر واحد في المحلول ارتباط ليكند واحد بشكل انيوني من خالل ذرة الكبريت و نتروجين مجموعة البريدايل و نتروجين مجموعة 1 H, 13 C بينت دراسات الرنين النووي المغناطيسي. االيزوميثانيك و ذرتي كلور باالضافة الى مجموعة االوكسو من جهة اخرى بينت الدراسات اعاله ان الشكل. [ تواجده بشكل ايزومرين في المحلولReOCl2(L)] للمعقد الفراغي حول ايون الزنك هو ثنائي الهرم المثلث حيث ترتبط جزيئة واحدة من اليكند ثالثية السن بشكل ثايون مع . مجموعتين من الكلور Thiosemicarbazones (tautomeric forms Introduction Thiosemicarbazones compounds Ia, Ib and Ic) are versatile ligands which exhibit a wide range of biological can coordinate as neutral ligands or in activity, which is dependent upon the their chemical nature of the moiety attached metal complexes have been studied to the C-S carbon atom.[1] In particular chemically heterocyclic thiosemicarbazones display crystallography.[6] very interesting biological properties, additional such as antitumour, antibacterial and phosphines, amines, hydroxyl or thiol antifungal activity.[2] The activity of the group at the residue R1 are of special uncomplexed thiosemicarbazone can be interest since they can coordinate in a increased significantly by the formation tridentate manner which results in a of metal complexes, as has been significant increase of the stability of the demonstrated previously in literatures.[3- complexes.[7] deprotonated form. and Numerous by Ligands donor groups such 5] S R 1 2 3 C N N C NH2 1 R H HS R 4 1 C N 2N 3N 4NH2 1 1b 1a 353 2 C N N 3N 1 R HS R 1 R X-ray H 1c 4 NH with as National Journal of Chemistry, 2006, Volume 23,352-367 Rhenium complexes with المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء prepared by a reductive ligand exchange thiosemicarbazones are rare due to their starting stability. The first structural report on [ReO4]-.[8] A recent publication reported such compounds was published dealing that, reduction of the metal ion can be with cationic ReIII compounds of the avoided and stable rhenium(V) oxo general composition [Re(L)2]+, where: L complexes represents a tridentate 2-acetylpyridine pyridineformamidethiosemicarbazones which the two nitrogen atoms of the (HL2) are used instead of HL1. X-ray hydrazones unit bind to each one of the crystallography showed the geometry rhenium atoms. about Re(V) is a distorted octahedral. They have been from [ReOCl3(PPh3)2] are formed when or 2- [9] obtained by Electron-Impact (EI), while Experimental Reagents were purchased from rhenium complexes were recorded on a Fluka and Redial – Dehenge Chemical VG autospec micromass spectrometer Co. I.R spectra were recorded as (KBr) operating under fast atom bombardment discs using a Shimadzu 8300 FTIR conditions (nitrobenzyl alcohol matrix). spectrophotometer in the range (4000- The spectra were recorded at University 400) cm-1. Electronic spectra of the of Free Berlin/Germany, and Queen prepared compounds were measured in Mary, the region (200-900) nm for 10-3 M Nuclear magnetic resonance spectra (1H, 13 solutions in (DMSO) at 25C using a University of London/UK. C-NMR) were acquired with Brucker Shimadzu 160 spectrophotometer, with 400, and Jeol EX400, EX270 Hz 1.0000.001cm matched quartz cell. spectrometers in DMSO-d6. The spectra were recorded at University of Free Mass spectrum for the ligand was 354 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء National Journal of Chemistry, 2006, Volume 23,352-367 Berlin/Germany, and Queen University of London/UK. Mary, [ReOCl2(L)] complex. Elemental [ReOCl3(PPh3)2] (0.162g, 0.194mmol) microanalyses were performed on a was added to a mixture of [HL] (0.05g, (C.H.N.) analyser from Heraeus (Vario 0.195mmol) in (20mL) MeOH. EL), Free mixture was heated at reflux under an Berlin/Germany. The chloride contents atmosphere of nitrogen for (2-3) hours, for complexes were determined by using during which time the colour of the potentiometer titration method on (686– reaction mixture became brown in Titro processor– 665Dosimat–Metrohm colour. The mixture was allowed to cool Swiss).Electrical conductivity to room temperature, and filtered off. A measurements of the complexes were red-brick solid was collected, washed recorded at 25C for 10-3 M solutions of with (5mL) cold MeOH and (5mL) Et2O. the samples in (DMSO) using a PW Yield (0.06g, 58%) of [ReOCl2(L)] . 9526 digital conductivity meter. [Re(L)2]Cl complex. [ReOCl3(PPh3)2] Synthesis (0.162g, 0.194mmol) was added to a [ReOCl3(PPh3)2] was prepared by a mixture of HL (0.1g, 0.39mmol) in literature procedure.[10] The ligand [HL] (35mL) MeOH. The mixture was heated was conventional at reflux under an atmosphere of procedure[11]: 2-formylpyridine (3.0g, nitrogen for 4 hours, during which time 28mmol) and 4-phenylthiosemicarbazide the colour of the reaction mixture (4.65g, became brown in colour. The mixture at the University synthesised 28mmol) by were of added to to room heated at reflux under an atmosphere of temperature, and filtered off. The nitrogen for 4 hrs. The reaction mixture solvent of the filtrate was reduced under was room vacuum to ca. (6mL), and a black-brown A crystalline precipitate solid was formed upon addition of methanol (20mL). allowed temperature. to was The mixture was cool to allowed to cool The formed which was collected by filtration (20mL) Et2O. and washed with a small amount of cold recrystalised from CH2Cl2/n-hexen, to methanol and copious quantities of give diethyl ether to give the ligand as large compound. beige crystals, 5.4g (75%). 355 (0.091g, The precipitate was 63%) of the title National Journal of Chemistry, 2006, Volume 23,352-367 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء from in colour, and a precipitate was formed. [NH4][ReO4] (0.1 g, The solid was collected by filtration, 0.373 mmol) was added to a mixture of washed with methanol (5mL) and dry methanol (20mL), triphenylphosphine ethyl ether (10mL), and dried under (0.4g, 1.52 mmol) and HCl (37 %) vacuum to give 0.063g, (82%) yield of (1mL). The mixture was heated at reflux the title compound. under an atmosphere of argon for 1 hour. Results and Discussion The mixture was allowed to cool to room Synthesis of the ligand temperature, and triethylamine (1.5mL), The Schiff base ligand was prepared by (HL) (0.19g, 0.74mmol) in (12 mL) the methanol was added. The mixture was carboxaldehyde heated at reflux under an atmosphere of phenylthiosemicarbazide nitrogen. The mixture was filtered hot The and the solvent was reduced to about (8 elemental mL) by evaporation under reduced (Table2), (U.V-Vis) (Table3), mass pressure. The mixture was left to stand spectroscopy, 1H and Synthesis of [NH4][ReO4]. 0 [Re(L)2]Cl at 4 C overnight. condensation ligand of with was pyridine-2the (Scheme1). characterised analysis (Table1), 13 4- by IR C NMR spectra The black-brown (Table4). The IR spectrum (Figure1-1) crystals were collected by filtration, and showed several strong bands at (1596) washed with cold methanol (1mL) and and (1550, 1496, 1465)cm-1 assigned for Et2O (5 mL) to give [Re(L)2]Cl (0.1g, υ(C=N) imine and [υ(C=N) pyrdiyl + 37%). υ(C=C)] stretches respectively. Analytical data was consistent The with the compound synthesised from bands at (3305) and (3120) cm-1 were [ReOCl3(PPh3)2]. assigned to υ(N(4)-H) and υ(N(3)-H) [ZnCl2(HL)] complex. To a stirred respectively. The latter band indicated solution of [HL] (0.05g, 0.195 mmole), the presence of the ligand in the thion in methanol (20 ml) was added slowly a form.[12] The spectrum showed no band solution of ZnCl2 (0.026g, 0.195mmole) around ca. (2550)cm-1 that could be in related to υ(S-H). methanol (10ml). The resulting The (U.V.-Vis) mixture was heated under reflux for 3 spectrum exhibits a highly intense hours under nitrogen atmosphere, during absorption peak at (211 nm) (47393cm-1) which time the solution became a yellow (max =4410 molar-1cm-1) and (328nm) 356 National Journal of Chemistry, 2006, Volume 23,352-367 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء 13 (30407cm-1) (max =1720 molar-1cm-1) C=N(2)) imine. which were assigned to (*) and showed a signal at chemical shift respectively.[13] (176.34)ppm was attributed to (C=S). Whilst the peak at (391nm) (25575cm-1) The EI(+) mass spectrum of the ligand (max =334 molar-1cm-1) was assigned to showed the parent ion peak at m/z= 256 (n*) transitions 1 charge transfer. C NMR spectrum (M)+, and the following fragments; 178= H NMR spectrum in (DMSO-d6) (Figure2) displayed signals (M-py)+, at 136= [M-{py+HC=N-NH}]+, 92= [M-{ chemical shifts (12.11) and [M-{py+HC=NH}]+, 150= (10.33)ppm attributed to δ(N(3)-H) and py+HC=N-NH-C=S}]+, δ(N(4)-H) respectively. py+HC=N-NH-C=S-NH}]+.[14] The chemical 77= [M-{ shift at (8.12)ppm assigned for δ(H- 3 4 2 H2N H N NH MeOH , Reflux C NH S + 6 5 1 N 1 N 2 O H N 7 H 8 3 C N 4 S 9 10 11 13 12 Scheme (1) The synthesis route of the ligand (Scheme2). Reduction of Re(V)-oxo to Synthesis of the complexes New rhenium and zinc Re(III) and the formation of the cationic complexes are [Re(L)2]Cl complex as a black brown of solid is observed, when an excess of [ReOCl3(PPh3)2] with one equivalent of [HL] is used and the reaction mixture is the tridentate ligand [HL] in MeOH at heated under reflux for a prolonged time. reflux and under nitrogen atmosphere The reduction of the metal atom is most gave the monomeric neutral complex probably due to the liberated PPh3. This [ReOCl2(L)] as a red brick solid has been observed previously for many thiosemicarbazone synthesised. The reaction 357 National Journal of Chemistry, 2006, Volume 23,352-367 reactions starting المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء from perrhenate by the addition of HCl and [ReOCl3(PPh3)2],[15] including exchange PPh3 as the reducing agent. Whilst the reactions with ligands of the type reaction [HL2][7]. However, the nature of the equivalent of the tridentate ligand [HL] incoming ligand is essential to control in MeOH at reflux and in the presence of the composition and oxidation state of PPh3 and HCl gave intractable black the metal atom in the products. Whereas solid (see Scheme2). On the other hand exclusively rhenium(III) cations of the [ZnCl2(HL)] was obtained as a neutral [Re(L)2]+ composition of [ReVIIO4]- with one and yellow solid from the reaction of ZnCl2 be with [HL] in MeOH at reflux and under acetylpyridine nitrogen atmosphere. These complexes thiosemicarbazones [HL2] are used.[8] are stable in solution and in solid state. The reaction with the corresponding 2- The molar conductance of the complexes pyridineformamide derivatives [HL1][8] [ReOCl2(L)] or N(4)- (DMSO) lies in the (15.3-12.5) S cm2 be mole-1 range, indicating their non- decomposition isolated with products when could 2-formylpyridine phenylthiosemicarbazone can and [ZnCl2(HL)] performed stepwise (see Scheme2) and electrolytic oxorhenium(V) intermediates can be conductance of [Re(L)2]Cl in (DMSO) is isolated in reasonable yields. This (51.3) S cm2 mole-1, indicating its behaviour demonstrated that, the nature electrolytic nature with (1:1) ratio,[17] of substituents on -N(2) and/or -N(4) of (Table3). The analytical and physical the thiosemicarbazones is crucial to data (Table1) and spectral data (Tables stabilize metal atoms in higher oxidation 2, 3 and 4) are compatible with the states.[16] Significantly in terms of the suggested structures (Figure3). possible for atom numbering for the complexes [Re(L)2]+ described is the same as that employed application radiopharmaceuticals, the complex was prepared directly from nature. While in in the ligand synthesis (Scheme1). 358 the The المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء National Journal of Chemistry, 2006, Volume 23,352-367 [ReOCl3 (PPh 3)2 ] eO at N2 H, a tm Re fl o s ux , ph H ere L M H ,R m os x, + 2H L 2 e eO er M lu ph N ef H Re S N H H Re N N N H L, PPh3 MeOH , Reflux, N 2 atmosphere N O N N Cl N N H S NH N S HN eO H ,R ef ef m at ,R H M h3 N P eO ,P e L er ,H ph x lu os 2 N 2 a tm lu x os , 2 ph H er L , e PP h M X 3 Cl [ReO 4 ]- Scheme (2) The synthesis route of rhenium complexes Table (1) Analytical and physical data of the ligand and its complexes Compound [HL] [Re(L)2]Cl [ReOCl2(L)] [ZnCl2(HL)] m.poc Colour Yield% White 199 75 Dark brown 175 63 >300 Red brick >300 Yellow 58 82 Found, (calc.)% S N C H (60.91) 60.50 (42.76) 43.19 (29.60) 29.50 (39.87) 39.32 (4.72) 4.89 (2.76) 3.01 (1.91) 1.65 (2.83) 2.40 (21.86) 21.90 (15.34) 14.97 (10.62) 10.23 (14.31) 14.22 (12.55) 12.77 (8.78) 8.61 (6.08) 5.89 (8.19) 8.20 Cl ----(4.85) 4.73 (13.44) 14.02 (18.11) 18.43 (Calc.) : Calculated IR Spectra 1600 cm-1, indicating coordination of the The IR bands most useful of determining imine nitrogen N-(2). The spectrum of the of the ligand shows the thioamide IV band, coordination are shown in (Table2). which at 870cm-1, and it shifts to higher The [ReO(L)Cl2] energy and appears at 891cm-1 on (Figure1-2)shows the υ(C=N) band of coordination of the ligand. The absence the ligand at 1596 cm-1 undergoes small of (N(3)-H) band at 3120cm-1, indicates shifts to higher frequency and appear at the coordination of the ligand in thiol thiosemicarbazones IR spectrum of mode 359 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء National Journal of Chemistry, 2006, Volume 23,352-367 form. The spectrum shows band at coordination of the ligand to Zn(II) ion 979cm-1 characteristic of the υ(Re=O) in thion form. stretching,[18] additional evidence for Electronic Spectra coordination of the imine nitrogen is the The (U.V-Vis) spectrum of the complex presence of υ(M-N) band at 432cm-1.[19] [ReOCl2(L)] displayed absorption peaks The IR spectrum of the [Re(L)2]+ at complex demonstrates molar-1cm-1) and a shoulder at (338nm) symmetric coordination of the two (29585cm-1) ( max =390 molar-1cm-1) thiosemicarbazone ligands through the assigned for ligand field. The peak at nitrogen atoms of pyridine, azomethine (420nm) (23809cm-1) ( max =225 molar- groups and sulfur atoms, similar to the 1 Re(III) (3T1g(p) 3T1g). (Figure1-3) complex with anionic (216nm)(46296cm-1)( max =4420 cm-1) assigned to (d-d) transition type This result is in thiosemicarbazone ligand, for which X- agreement with that reported for oxo- ray analysis Re(V) with octahedral geometry.[21, confirmed a distorted octahedral geometry. The spectrum [Re(L)2]Cl shows no band related to the υ(Re=O). 1 at 3126cm-1, indicates the coordination The peak at (390nm) (25641cm-1) (max =1570 molar-1cm-1) was assigned to charge transfer. Whilst 4)shows the imine υ(C=N) band of the ligand at 1596 cm four ) ( max =4410 molar-1cm-1) assigned to ligand field. The IR spectrum of [Zn(HL)Cl2] (Figure1-1 exhibits absorption peaks at (215nm) (46511cm- Moreover the absence of (N(3)-H) band of the ligand in thiol form. complex 22] the peaks at (451nm) (22172cm-1) ( max shifts to higher =788 molar-1cm-1) and a broad peak at -1 frequency and appear at 1620 cm , (605nm) (165281cm-1) ( max =195 indicating coordination of the imine molar-1cm-1) were attributed to d-d nitrogen N-(2). This increase is due to transitions type (1T2g 1A2g) and (1T2g weaker coordination to the central ion in 1T1g) respectively. This result is in comparison with rhenium.[20] The band agreement with that reported for Re(III) at 3126 cm-1 was attributed to ( N(3)-H) complexes with a distorted octahedral in the IR spectrum of the ligand is still geometry.[23] The [ZnCl2(HL)] complex exist in the complex spectrum, and shows three absorption peaks at (215nm) appeared at 3197cm-1 indicating the 360 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء National Journal of Chemistry, 2006, Volume 23,352-367 (46511cm-1) (max =4410 molar-1cm-1) belong to d10 system, the peak at and (329nm)(30395cm-1) (max =1844 (408nm) (24509cm-1) (max =210 molar- molar-1cm-1) assigned to ligand field. 1 cm-1) was assigned to charge transfer. Since the metal ion of the complex Table (2) I.R spectral data (wave number ) cm-1 of the ligand [HL] and it’s complexes Compound [HL] [Re(L)2]Cl (N(4)-H) (C-H) (N-NH) 3305(w) 3126 2947(w) ---3166 3043, 2927 (C=N) imine 1597(s) 1600 Additional (C=C) (N-N) (C-S) (M-N) peaks (C=N) 1550(sh) 995 870 756, 690 1496(sh) (C-H) Out of plane 1004 903 1523 1458 1022 891 [ReOCl2(L)] ---3262 [ZnCl2(HL)] 3259 3197 3066, 2927 3028 1596 1554 1492, 1458 1612 1558 1492, 1446 1010 906 756, 690(C-H) Out of plane 979 (Re=O). 432(w) 752, 690(C-H) Out of plane. 759, 694 415(w) (C-H) Out of plane. 428(w) Recorded as KBr: s: strong, m: medium, w: weak. Table (3) Electronic spectral data and conductivity measurement of [HL] and its metal complexes Compound [HL] [Re(L)2]Cl [ReOCl2(L)] [ZnCl2(HL)] nm 211 328 391 215 390 451 605 216 338 420 215 342 409 cm-1 max –1 -1 (molar . cm ) 47393 30407 25575 46511 25641 22172 16528 46296 29585 23809 46511 30395 24509 4410 1720 334 4420 1570 786 195 4420 390 270 4410 1844 210 361 ΛM(Ω-1 cm2mol1) Ratio 51.3 (1:1) 15.8 Neutral 12.5 Neutral National Journal of Chemistry, 2006, Volume 23,352-367 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء Figure 1 (IR) spectra (cm-1) of: (1-1) The ligand [HL] (1-2) The complex [ReO(L)Cl2] (1-3) The complex [Re(L)2]Cl (1-4) The complex [Zn(HL)Cl2 and the following fragments; 459= (M- Mass Spectrum of 2Cl)+, 467.9= [M-{C=S+O}]+, 408.8= [ReOCl2(L)] showed peaks which could [M-{2Cl+(C=S)+O}]+, 354= [M-{O+(N- be N-C=S)}]+, The FAB(+) assigned mass to a spectrum composition of 153= [M-{ O+(N-N- [ReOCl(L)]+ at m/z= 492 (M-Cl)+. No C=S)+(H2C=CH2}]+ evidence, however, was found for the FAB(+) mass spectrum of [Re(L)2]+ molecular ion peak at m/z= 528 (M) +, showed the following fragments ions 362 detected. The National Journal of Chemistry, 2006, Volume 23,352-367 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء peak at m/z= 587= [M-(Ph+S)]+, 560= absence of a resonance assigned to the [M-(Ph+HN-C=S)]+, 542= [M-(2Ph)]+, hydrazinic proton which is readily 250= [M-2(Ph+HN-C-NH-N=CH-py)]+. detectable in the spectrum of the free NMR Studies ligand at δ=12.11ppm. The Re(V), Re(III) and Zn(II) complexes spectra suggested the presence of the are diamagnetic (Table 4). The 1H and [Re(L)2]Cl complex as a single species 13 C NMR spectra of Re(III) complex in solution. 1H and 13C NMR spectra of show well defined narrow lines which is Re(V) complex showed well defined unusual for what formally d4 octahedral downfield lines in comparison with that system and might show the nature of the for Re(III) and Zn(II) spectra. This can delocalisation ligand. It was suggested be attributed to the high oxidation state that binding of the pyridine nitrogen to of the metal centre, which is formally d2 form a chelate may account for the system. The NMR spectra of Re(V)-oxo diamagnetic nature of the complexes due complex suggest the presence of two to the π-system in which the lon pair of isomers in solution. The signal for the electrons is donated by pyridine nitrogen C-S carbon comes at about δ= 193.62 into the t2g set of the metal.[24] Similar ppm for isomer A and at 184.00 ppm for mechanisms may be involved in the isomer B compared with δ= 176.34 ppm thiosemicarbazone system. in the free ligand and is consistent with spectrum of Re(III) The NMR complex is thiolate consistent with the symmetric nature of the complex. The like The NMR coordination to rhenium(V) rather than thion. 13 the The C NMR of the deprotonation of the ligand is confirmed complex is shown in (Figure2) and in the 1H NMR spectrum of Re(V)-oxo exhibits 13 resonances. The signal for complex by the absence of a resonance the C-S carbon comes around δ= 186.51 assigned to the hydrazinic proton which ppm compared with δ= 176.34 ppm in is readily detectable in the spectrum of the free ligand which is consistent with the free ligand at δ=12.11ppm. thiolate type coordination to the rhenium addition, the rather than thion.[8] The deprotonation Re(V)-oxo complex shows resonances at of the ligand is confirmed in the 1H chemical shift 10.80 and 10.68 ppm NMR spectra of Re complex by the which were assigned to N(4)-H of 363 1 In H NMR spectrum of National Journal of Chemistry, 2006, Volume 23,352-367 isomers A and B respectively. These signals are disappeared on addition ofD2O to the NMR solution supporting the presence of two isomers in solution. There are several possibilities for isomers of asymmetric tridentate ligands, one is the differing in the disposition of the Re=O group. superimposable These are non- enantiomers, which might be observed in solution by NMR spectroscopy. isomers There are also possible involving different conformations of the backbone which should occur also for Re(III) complex, but are not apparently observed. This observation suggests this is not the case. On the other hand the 13 C spectrum for Zn(II) (Figure2), shows the signal for the C-S carbon at δ= 176.49 ppm which is consistent with thion like coordination to the zinc. This has been confirmed by the 1H NMR spectrum of the presence of the hydrazinic proton at δ=12.11ppm. 364 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء National Journal of Chemistry, 2006, Volume 23,352-367 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء Table (4) 1H, 13C NMR Data for the ligand and its complexes measured in DMSO-d6 and chemical shift in ppm () Compound Funct. Group s (p.p.m) b -N-N(2)-H a; - N(4)-H a; -N=C-H; 12.11 (1H, s, br.); 10.33 (1H, s); 8.67 (1H, s); Ar- H; Ar- H Ar- H; Ar- H 8.47(1H, s);8.23 (s, 1H) 8.11 (1H, s); 7.88-7.44(m, 6H) (C7-S); (C6=N); (C5); (C1); (C8); (C3); 176.32; 153.04; 149.22; 142.97; 138.84; 136.35; (C10,11); (C9,13); (C2); (C11); (C4). 127.98; 125.87; 124.93; 124.10; 120.52. - N(4)-H a; -N=C-H ;Ar- H 11.48 (1H, s); 8.48 (1H, s);8.34 (1H, d, JH-H = 7.4 Hz) Ar- H ;Ar- H 7.88 (2H, d, JH-H = 0.8 Hz) ;7.75 (1H, d, JH-H = 9.76 Hz) Ar- H; Ar- H; Ar- H ; Ar- H. 7.60 (1H, s); 7.39 (1H, s)7.22-7.15 (1H, m); 6.95 (1H, s) (C7-S); (C6=N); (C5); (C1); (C8); (C3); 186.51; 159.40; 158.48; 140.78; 136.82; 133.09; (C10,11); (C9,13); (C2); (C11); (C4). 129.01; 127.99; 126.70; 123.78; 120.08. - N(4)-H a 10.80 (1H, s) -N=C-H 9.03 (1H, s) [HL] 1 H 13 C [Re(L)2]Cl 1 H 13 C [ReOCl2(L)] 1 H Isomer A Isomer B 13 - N(4)-H a 10.68 (1H, s) -N=C-H 8.81 (1H, s) (C7-S); (C6=N); (CAr); (CAr); (CAr); 193.62; 161.13; 151.06; 141.23; 129.81; (CAr);(CAr); (CAr); (CAr); (CAr); (CAr). 129.00; 128.70; 128.40; 127.97; 124.82; 121.73. (C7-S); (C6=N); (CAr); (CAr); (CAr); 184.00; 162.13; 154.91; 150.16; 143.12; (CAr); (CAr); (CAr);(CAr); (CAr); (CAr). 137.78; 129.28; 126.41; 125.99; 124.82; 123.59. -N-N(2)-H a;; N(4)-H a; -N=C-H; Ar- H; Ar- H; Ar- H; Ar- H; Ar- H; Ar- H. 12.11 (1H, s,) ; 10.33 (1H, s); 8.63 (1H, s) 8.45 (1H, s); 8.21 (1H, s); 8.08 (1H, s); 7.58 (1H, s); 7.28 (2H, s); 7.11 (1H, s). (C7-S); (C6=N); (C5); (C1); (C8); (C3); (C10,11); (C9,13); (C2); (C11); (C4). 176.49; 151.86; 148.04; 140.97; 139.01; 138.36; 128.19; 125.97; 125.03; 124.65; 121.64. C Isomer A Isomer B [ZnCl2(HL)] 1 H 13 C a disappears on D2O exchange; b chemical shift from TMS. 365 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء National Journal of Chemistry, 2006, Volume 23,352-367 Figure 2 13C NMR spectra of the complexes (DMSO-d6) + Cl H N N Cl N N Re N O S S N Re S N H N N N N N H The proposed structure of [Re(L)2]+ The proposed structure of [ReOCl2(L)] Cl Cl S Zn H N N N N H The proposed structure of [ZnCl2(HL)] Figure 3 The suggested structure of the complexes 366 National Journal of Chemistry, 2006, Volume 23,352-367 المجلد الثالث والعشرون-6002-المجلة القطرية للكيمياء Chemistry II, vol. 5, Elsevier, 2003, 271. 16- I. G. Santos, A. Hagenbach and U. Abram, J. Chem. Soc. Dalton Trans., 2004, 677. 17- W. J. Geary, Coord. Rev., 1971, 7, 81. 18- M. J. Al-Jeboori and Ayed Al-Shihri, J. Saudi Chem. Soc., 2001, Vol. 5, No.(3), 341. 19- Mohamad J. Al-Jeboori and Abdul Aziz Kashta, Mu'tah Lil-Buhuth Wad-Dirasat, 2004, Vol. 19, No (1), 89. 20- M. Sumar, I. Ivanovic-Burmazovic, I. Hodzic, and K. Andjelkovic, Synth. React. Inorg. Met-Org. Chem., 2002, Vol. 23, No.(4), 721. 21- M. J. Al-Jeboori, T. A. Himdan and A. A. Al-Hamdani, Iraq. J. Chem., 2002, Vol. 28, No.(2), 293. 22- A. B. P. Lever, "Inorganic Electronic Spectroscopy", 2nd Edition, New York, 1984. 23- M. J. Al-Jeboori, M. A. Mustafa and S. A. Al-Hamzawi, Iraq. J. Chem., 2002, Vol. 28, No.(1), 85. 24- M. Hirsch-Kuchma, T. Nicholson, A. Davison, W. M. Davis and A. G. Jones, Inorg. Chem., 1997, 36, 3237. References 1- A. R. Cowley, J. R. Dilworth, P. S. Donnelly, A. D. Gee and J. M. Heslop, J. Chem. Soc., Dalton Trans., 2004, 2404. 2- D. X. West, S. B. Padhye and P. B. Sonawane, Struct. Bonding (Berlin), 1991, 76, 1. 3- D. H. Petering, Bioinorg. Chem., 1972, 1, 255. 4- D. X. West, A. E. Liberta, S. B. Padye, R. C. Chikate, P. B. Sonawante, A. S. Kumbhar, and R. G. Yerandle, Coord. Chem. Rev., 1993, 123, 49. 5- P. V. Bernhardt, J. Mattsson, and D. R. Richardson, Inorg. Chem., 2006, 45, 752. 6- J. S. Casas, M. S. Garcia-Tasenda, J. Sordo, Coord. Chem. Rev., 2000, 209, 49. 7- G. Pereiras-Gabian, E. M. VazquezLopez and U. Abram, Z. Anorg. Allg. Chem., 2004, 630, 1665. 8- A. R. Cowley, J. R. Dilworth, P. S. Donnelly, J. Woollard-Shore, J. Chem. Soc. Dalton Trans. 2003, 748. 9- I. G. Santos and U. Abram, Z. Anorg. Allg. Chem., 2004, 630, 697. 10- J. Chatt and G. A. Rowe, J. Chem. Soc., 1962, 4019. 11- D. L. Klayman, J. F. Bartosevich, C. J. Griffin, J. Mason and J. P. Scovill, J. Med. Chem., 1979, 22, 855. 12- D. A. Thornton,. Coord.Chem. Rev., 1990, 104, 251. 13- W. Kemp, "Organic Spectroscopy" 2nd. Edition, 1987, 144. 14- J. R. Chapman, “Practical Organic Mass Spectrometry”, 2nd, Edition, Wiley, 1995. 15- U. Abram, Rhenium in J. A. Mc Cleverty, T. J. Meyer (Ed.), Comprehensive Coordination 367