西北大学学报(自然科学网络版)
Science Journal of Northwest University Online
2003 年 11 月 第 5 期
Nov. 2003 No. 5
Preparation, crystal structure and standard
enthalpy of formation of Cu(AMP)2Cl2
FAN Xue-zhong 1, 2, XIE Gang 1, CHEN San-ping 1,
GAO Sheng-li 1 , SHI Qi-zhen 1
（1. Shaanxi Key Laboratory of Physico-Inorganic Chemistry / Department of Chemistry, Northwest University, Xi’an 710069,
China; 2. Xi’an Modern Chemical Institute, Xi’an 710065, China
Abstract: The complex [Cu(AMP)2Cl2] of copper chloride and 2-amino-4, 6-dimethyloxyl pyrimidine
(AMP) was prepared, and the composition of the complex was determined by chemical and elemental
analyses. The complex was characterized by IR, XPS, and 1H NMR. In addition, X-ray structural
analysis was performed. The crystals is orthorhombic, space group Pbca with crystallographic
parameters of a = 1.301 5(5), b = 1.382 2(5), c = 2.009 3(7) nm, V = 3.615(2) nm3, Z = 8, Dcalc = 1.635
Mg / m3, F(000) = 1 816,  (Mo K) = 0.071 073 nm,  = 1.534 mm-1, T = 293 K, wR2 = 0.147 1, R =
0.065 2 for 1 916 observed reflections. The constant-volume combustion energies of AMP and
[Cu(AMP)2Cl2], ΔcE determined by a precise rotating bomb calorimeter at 298.15 K were (–3 340.01±
1.54) and (-5 684.22±2.24) kJ/mol, respectively. The standard enthalpy of combustion were (–3 339.39
±1.54 kJ/mol and (–307.91±1.74) kJ/mol for AMP, and (–5 678.0±2.24) kJ/mol and (–1 670.59±
2.73) kJ/mol for [Cu(AMP)2Cl2].
Key words: copper chloride; 2-amino-4,6-dimethyloxyl pyrimidine; standard enthalpy of combustion;
standard enthalpy of formation
CLC number: O642. 3+
Document code: A
Article ID: 1000-274X(2003)0032-08
The pyrimidines as a class are known to possess extraordinary biological properties that are generally
distinguished qualitatively by their applications in pesticide, herbicide, bactericide, and medicine intermediates [1].
A survey of these applications and a number of the related variations that were developed recently, such as the
extraordinary effective herbicide of sulfonyl sulfourea, reveals the broad biological importance just because of the
wide occurrence of pyrimidines ring systems in these molecules
[2].
It has been shown that the medicine
intermediates in the complexes of metal ions and pyrimidines could prolong the pharmaceutical activity and
effective life, and reduce the damage to mammal
[1, 3~8].
When the complexes of Pt or Pd and pyrimidine, are
employed as medicine addictives, they are harmful to human body, especially to some organ such as kidneys,
although they are identified as the most effective drugs used to treat cancer by now. If Pt and Pd in these
________________________
Received date:2003-08-28
Foundation item: The Education Committee Foundation of Shaanxi (HF01304)
Referee: HU Rong-zu,, male, professor, Xi'an Modern Chemical Institute
complexes were replaced by such microelements that are necessary for the life as Cu, Zn or Co, etc, the toxicity
and the side effect of these complexes would be decreased while the power and efficiency of the medicine are
preserved.
In this work, on the base of the literature
[7, 8]
, the synthesis of 2-amino-4, 6-dimethyloxyl pyrimidine (AMP)
was ameliorated using triethylb enzylamine chloride (TEBA) as catalyst and the yield was improved. The solid
complex of CuCl2 and AMP were prepared in alcohol, the compositions of the complex were determined by
chemical and elemental analyses, and the complex was characterized by spectral measurements (IR, XPS, NMR).
In addition, X-ray structural analysis was performed. The constant volume-combustion energies of the ligand and
the complex were determined by a precise rotating bomb calorimeter, The standard combustion enthalpy and the
standard formation enthalpy were calculated. Clearly the study of the complex, both in practice and theory, is very
substantial significant for further application.
1 Experimental
1.1
Materials
All chemicals and solvents used were of A.R. grade and used after further purification. Guanidine nitrate and
diethyl malonate were obtained from Shanghai chemical factory and phosphorus oxychloride, alcohol,
CuCl2·2H2O, triethylbenzylamine chloride, and sodium methylate were obtained from Xi’an chemical factory.
1.2
Preparation of ligand
2-Amino-4, 6-dihydroxyl pyrimidine was synthesized according to the method given in Ref .[9]. The white
solid product of the yield of 80%, with the melting point of exceeding 330℃, was obtained.
Referred to Ref. [9], the synthesis method of 2-amino-4, 6-dichloride pyrimidine was ameliorated by
selecting TEBA as catalyst and agitating continually. The straw yellow product with the yield of 80% was
obtained, m. p. = 224~225 ℃, which was better than that of the literature (223~225 ℃).
Finally, combining the results above and of Ref. [10], the white crystal of AMP was collected. The yield of
AMP was beyond 80%, and its melting point is in the range of 97.0~ 97.5 ℃. Anal. Calc. for C6H9N3O2: C, 46.43;
H, 5.85; N, 27.09. Found: C, 46.35; H, 5.98; N, 27.20. 1H NMR δ(-OCH3) = 3.757, δ(=CH-) = 5.347, δ(-NH2) =
6.563.
1.3
Preparation of complex
0.93 g of the ligand and 0.52 g of CuCl2·2H2O were separately dissolved in 15 cm3 and 10 cm3 of alcohol.
When the solution of CuCl2·2H2O was warmed for a few minutes on a hot plate, the solution of the ligand was
added dropwise into the solution of salt. Under the condition of reflux, the reaction proceeded further for 3 h.
After evaporating a part of solvent, the precipitant appeared, and the reaction mixture was allowed to cool slowly
to the room temperature, followed by suction filtration. In order to remove the reminder of the ligand and salt, it is
necessary for the reaction mixture to be rinsed thoroughly with hot alcohol and distilled water. An infrared heat
2
lamp was employed to serve the drying of the product. Finally, the white product of the yield of 75.6 % with the
melting point of 162.0~162.1 ℃ was obtained. Crystals suitable for X-ray analysis were obtained by
recrystallization of power sample from alcohol solution. The analytical results of the composition of the complex
are presented as follows. Anal. Calcd. for C6H9Cl2N3O2Cu: C, 32.41; H, 4.08; Cl, 15.95; N, 18.90; Cu, 14.29.
Found: C, 32.91; H, 4.18; Cl, 15.94; N, 19.20; Cu, 13.98. 1H NMR:δ(-OCH3) 3.762, δ(=CH-) 5.421, δ(-NH2) 6.559
ppm.
1.4
Instruments
Melting point of the compounds was measured with WRS-1A digital melting-point apparatus. C, H, N
contents were determined on a Perkin-Elmer 2 400 type elemental analyzer. Infrared spectra of samples were
recorded in KBr discs for 4 000~400 cm-1 on a Bruker EQ UINOX-550 spectrophotometer. XPS were taken on a
ESCA PHI-5400 X-ray photoelectron spectrophotometer using Mg Kα radiation. The C1s electron in benzene was
used as the internal standard, BE = 284.6 eV, and the accuracy of the measured BE value was +0.1 eV. The NMR
spectra were carried out with a Varian Unity INOVA-400 nuclear magnetic resonance spectrometer using TMS as
the reference sample and C2D5OD as the solvent.
1.5
X-ray data collection of the complex
Crystal evaluation and data collection for 0.555 mm × 0.434 mm × 0.323 mm blue crystal were performed
on a Bruker SMART CCD-1000 diffractometer with graphite-monochromated MoK ( = 0.071 073 nm)
radiation. The 3 358 reflections were collected for the 2 θ range 4.06 to 51, and the 1 916 independent
reflections with I>2σ (I) were used in the refinement. The structures were solved with the direct methods of
SHELXS-97 and refined with full-matrix least-squares technique using SHELXL-97. Non-hydrogen atoms were
refined anistropically. The hydrogen atoms of the organic ligands were generated geometrically.
1.6
Determination of constant-volume combustion energy
The constant-volume combustion energies of the compounds were determined by a precise rotating bomb
calorimeter
[11].
The main experimental procedures were described in Ref. [11]. The initial temperature was
regulated to (25.000 0±0.000 5)℃, and the initial oxygen pressure was 2.5 Mpa. The correct value of the heat
exchange was calculated according to Linio-Pyfengdelel-Wsawa formula [9]. The calorimeter was calibrated with
benzoic acid of 99.999% purity. It had an isothermal heat of combustion at 298.15K of (–264 34±3) J / g . The
energy equivalent of calorimeter was determined to be (17 936.01±9.08) kJ / K . The analytical methods of final
products (gas, liquid and solid) were the same as those in Ref [12].
2
2.1
Results and discussion
Crystal structure
The crystal structure was found to be orthorhombic, which belongs to space group Pbca with
crystallographic parameters of a = 1.301 5(5), b = 1.382 2(5), c = 2.009 3(7) nm, V = 3.615(2) nm3, Z = 8, Dcalc
3
= 1.635 Mg/m3, F(000) = 1 816,  (Mo K) = 0.071 073 nm,  = 1.534 mm-1, T = 293 K, Rint = 0.1513, wR2
=0.1471.Coordination sphere of a Cu (II) forms a distorted tetrahedron geometry with two chlorines and two
pyrimidine nitrogens (Fig. 1). Unlike the reported similar complex [13], which exist equivalent M–Cl or M–N
distances, in this complex, Cu–Cl(1), Cu-Cl(2), Cu–N(1) and Cu–N(4) distances are 0.228 59(16), 0.227 99(16),
0.206 7(4) and 0.205 3(4) nm, respectively. The Cl–Cu–Cl angle is 108.03(6)º, N(1)–Cu–N(4) angle is
120.69(16)º, while N(1)–Cu–Cl(1), N(4)–Cu–Cl(1), N(1)–Cu–Cl(2) and N(4)–Cu–Cl(2) angles are 108.54(12),
105.48(12), 105.69(12) and 107.90(12)º, respectively.
Fig. 1 Molecular structure of [Cu(AMP)2Cl2]
Due to the coordination of two chlorines, the N(3)–H(2) and N(6)–H(7) group form an intramolecular
interaction with Cl(1) and Cl(2), respectively, the N(3)Cl(1) and N(6)Cl(2) distances being 0.322 7 and
0.320 1 nm, while the N(3)–H(1) and N(6)–H(8) group form a weak intermolecular interaction with Cl(2)[x -1/2,
-y +1/2, -z +1] and Cl(1)[x +1/2, y, -z +3/2], respectively, the N(3)Cl(2) and N(6)Cl(1) distances being
0.352 6 and 0.349 8 nm. The HCl distance is shorter than the sum of the entity radii (ca. 0.3 nm) and therefore
could be considered as a hydrogen banding interaction, moreover, intermolecular H-band are stronger than
intermolecular H-band, which can be seen from the HCl distance, H (2)Cl (1) 0.244 7, H(7)Cl(2) 0.239 5,
H(1)Cl(2)[x +1/2, y, -z +3/2] 0.273 8, H(8)Cl(1)[x -1/2, -y +1/2, -z +1] 0.272 4 nm. For H1, H2, H7,
and H8, the calculated angles N-HCl are 156.62, 149.61, 164.55, and 157.55º, respectively.
The characteristic absorptions of C = N and C-N in the ring of pyrimidine have the shifts of 27 and 14 cm-1 in
contrast with those of the free ligand, indicating that nitrogen atom in the pyrimidine binds with copper ion.
Consulting Ref. [14], the binding energy data of the internal shell electron for the main atoms of the
compounds obtained from XPS spectra of the complexes, are listed in Tab.1.
Comparing with the binding energy of N1s in the pyrimidine ring, there is a marked change for that of the
complex, which showed one of the nitrogen atoms in the pyrimidine coordinate to Cu2+. The decrease of the
binding energy could interprete that rather amount of feedback of d electrons existing in the coordination bond of
N→Cu2+ leads to the increase of the electron cloud density of N1s. The binding energy of Cl- for the complex
distinctly changed, due to which it is assumed that Cl- coordinated to Cu2+. The binding energy of Cu2+ had a little
4
change, which illustrates certain degree of feedback bond existing in the coordination bond.
Tab. 1 Binding Energy Data
2.2
eV
Compound
N1s(amino)
N1s(the ring of pyrimidine)
N1s(Nitric acid)
Cl 2p 3/2
Cu 2p 3/2
AMP
400.1
398.2
－
－
－
CuCl2·2H2O
－
－
－
199.1
935.2
Cu(AMP)2Cl2
399.7
399.9
－
198.9
935.8
Thermochemical properties of Cu(AMP)2Cl2
Standard enthalpies of formation of ligand and complex were studied. The determination method of
constant-volume combustion energy for the sample was the same as the calibration of the calorimeter with
benzoic
acid.
The
combustion
 c E (sample, s) 
energies
of
the
samples
were
calculated
by
the
WT  aG  5.983J  cm 3b
m
formula
(1)
where  C E (sample, s) denotes the constant volume combustion energy of the samples, W is the energy
equivalent of the RBC-Ⅲtype calorimeter (in J/K), ΔT the correct value of the temperature rising, a the length of
actual Ni – Cr wire consumed (in cm), G the combustion enthalpy of Ni – Cr wire for ignition (0.9 J/cm), 5.983
the formation enthalpy and solution enthalpy of nitric acid corresponding to 1 cm3 of 0.100 0 mol/dm3 solution
NaOH (in J/cm3), b the volume (in cm3 ) of consumed 0.100 0 mol/dm solution of NaOH and m the mass (in g) of
the determined sample. The results of the calculations are given in Tab.2.
Tab. 2 Experimental results for combustion energies of ligand and complex
Compound
AMP
No.
m/g
qc/J
qn/J
ΔT/K
-cE/J.g-1
1
0.779 61
12.60
67.17
0.936 9
21 530.39
2
1.033 04
12.60
89.38
1.240 0
21 509.09
3
1.900 79
12.60
78.28
1.091 2
21 560.98
4
1.003 19
12.60
86.60
1.203 8
21 501.25
5
1.012 72
12.60
87.42
1.217 9
21 509.37
6
1.003 03
12.60
86.58
1.204 0
21 509.15
Mean
Cu(AMP)2Cl2
21 526.70±9.95
1
1.049 40
9.90
267.32
0.760 4
12 779.23
2
0.961 42
12.60
259.08
0.697 9
12 784.50
3
1.032 59
12.60
278.27
0.750 5
12 801.34
4
1.010 72
12,60
272.37
0.732 7
12 767.54
5
1.042 30
12.60
280.88
0.755 7
12 770.37
6
1.007 91
12.60
271.61
Mean
12 787.69
12 781.8±5.05
The standard combustion enthalpy of the compounds,  c H m , referred to the combustion enthalpy change of
5
the following ideal combustion reaction at 298.15 K and 101.325 kPa.
29
9
3
O2 (g) = 6CO2 (g) + H2O (l) +
N2 (g)
2
2
4
29
Cu(AMP)2Cl2 (s) +
O2 (g) = CuO (s) + 12CO2 (g) + 8H2O (l) + 2HCl (g) +3N2 (g)
2
C6H9N3O2 (s) +
(2)
(3)
The standard combustion enthalpies of the samples were calculated by the following equations:
H m, c  Ec  nRT
(4)
n  ng (products )  ng (reactants )
(5)
where ng is the total amount in mole of gases present as products or reactants, R = 8.314 J/mol  K , T = 298.15 K.
The results of the calculations were given in Tab.3.
The standard enthalpies of formation of the samples,  c H mθ , were calculated by Hess’s law according to the
following thermochemical equations:
9


 f, AMP(s) H mθ  6 f, CO 2 (g) H mθ   f, H 2O(l) H mθ    c, AMP(s) H mθ
2


(6)


 f, Cu(AMP)2 Cl 2 (s) H m0   f, CuO(s) H m0  12 f, CO 2 (g) H m0  8 f, H2O(l) H m0  2 f, HCl(g) H m0   c,Cu(AMP)2 Cl 2 (s) H m0
θ
θ
(7)
θ
where Δf,CuO(s) H m = –155.23 kJ/mol, Δf,CO 2 (g)H m = (–393.51±0.13) kJ/mol, Δf,H 2 O(l)H m = (–285.83±0.042)
θ
kJ/mol, Δf,HCl(g)H m = (–92.31±0.03) kJ/mol. The detailed list of the results of the calculations is presented in Tab.
3.
Tab. 3 Combustion energy, standard enthalpy of combustion and standard of formation
of ligand and complex
kJ·mol-1
Compound
  c,compound( s ) E
  c,compound(s ) H mθ
  f, compound( s ) H mθ
AMP
3340.01±1.54
3339.39±1.54
307.91±1.74
Cu(AMP)2Cl2
5684.22±2.24
5678.02±2.24
1670.59±2.73
References:
[1] ZHANG P Z, WU J, GONG Y Q. The systemization and bioactivity of pyrimidine copper and pyrimidine
zinc[J]. Chinese Journal of Applied Chemistry, 2000, 17(5): 558-560.
[2] LIU CH L. Proceeding of novel bactericide - pyrimidineamino [J]. Nongyao, 1995, 34(8): 25-29.
[3]
ZHANG
P
Z,
GONG
Y
Q,
SHI
X
Q,
et
al.
Investigation
on
complexes
of
2-methylamino-6-hydroxyl-4-methyl pyrimidine with copper and zinc [J]. Chemical research and application,
1997, 9(1): 92-94.
[4] Mishra L K. Complexes of palladium (Ⅱ) and platinum (Ⅱ) with some organic ligands[J]. J Indian Chem Soc,
6
1982, 59(3): 408 -409.
[5] MELANSON R, ROCHON F D. The molecular and crystal structure of (diethylenetriamine)(guanosine)
platinum diperchlorate [J]. Can J Chem , 1979, 57(1): 57-61.
[6] ALLAN J R. The preparation and thermal analysis studies on some first row transition metal complexes of
2-aminopyrimidine [J]. J Therm Anal, 1981, 21(1): 3-12.
[7] SINGH E B, CUPTA O P. Spectral and magnetic properties of copper (II) complexes with 2 - aminopyrimidine
and 2-amino-4-methypyrimidine [J]. J. Indian Chem Soc, 1987, 64(6): 359-361.
[8] PAAVO l, HANNU E. Antitumor activity and metal complexes of the first transition series.
Trans-bis(salicylaldoximato) copper (II) and related copper (II) complexes.:A novel group of potential
antitumor agents [J]. Inorg Chimica Acta , 1984, 92(4): 241- 251.
[9] XU K Q. Handbook of Fine Industrial Chemicals and Intermediate [M]. Beijing: Beijing Chemical and
Industrial Press, 1998.
[10] POPOV M M. Thermometry and Calorimetry [M]. Moscow: Moscow University Publishing House, 1954.
382.
[11] YANG X F, YANG X W, SUN L ZH. The Construction of a Rotating – Bomb Combustion Calorimeter and
the Determination of the Heat of Combustion of p – Chlorobenzoic Acid [J]. Chem J Chin Univ 1986, 7(4):
363-367.
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(5,7-diphenyl-1,2,4-triazolo[1,5-α]pyrimidine) zinc (II) (1) and dichlorobis (5,7 – diphenyl - 1,2,4- triazolo [1,
5-α]pyrimidine) cobalt (II) (2) [J]. Inorganic Chim Acta, 1997, 260(2): 145-150.
[14] KAZUO NAKAMOTO. Infrared and Roman Spectra of Inorganic and Coordination Compounds[M]. fourth
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（编辑 张银玲）
Cu(AMP)2Cl2 的制备、晶体结构和热化学研究
樊学忠
1, 2
1
1
1
, 谢 钢 , 陈三平 , 高胜利 , 史启祯
(1. 西北大学 化学系 / 陕西省物理无机化学重点实验室
陕西 西安
1
710069；2. 西安近代化学研究所
陕西 西安
710065)
摘 要：制备了配合物 Cu(AMP)2Cl2 (AMP = 2-氨基-4,6 二甲氧基-嘧啶)。通过元素分析、IR 光谱、XPS、
1H
NMR 和 X 衍射进行了结构表征，其晶体学数据如下：晶体为单斜晶系，Pbca 空间群，a = 1.301 5(5), b
= 1.382 2(5), c = 2.009 3(7) nm, V = 3.615(2) nm3, Z = 8, Dcalc = 1.635 Mg/m3, F(000) = 1 816，R = 0.065 2，wR2 =
0.147 1。同时, 用转动弹热量计测定了配体和配合物的恒容燃烧能，ΔcE 分别为(–3 340.01±1.54) 和(
7
–5 684.22±2.24) kJ/mol，配体的标准燃烧焓  c H m0 和标准生成焓  f H m0 分别为(–3 339.39 ± 1.54) kJ/mol 和
(–307.91 ± 1.74) kJ/mol, 配合物的标准燃烧焓  c H m0 和标准生成焓  f H m0 分别为(–5 678.02 ± 2.24)
kJ/mol 和 (–1 670.59 ± 2.73) kJ/mol。
关 键 词：CuCl2；2-氨基-4,6 二甲氧基-嘧啶；标准燃烧焓；标准生成焓
Profile of author
FAN Xuezong was born in Ningxia, P. R. China, in 1962. He received his B. S in chemistry
at Ningxia University in 1983 and M. S. in organic synthesis in 1992 at East China Normal
University. He completed his Ph. D. in applied chemistry at Beijing Institute of Technology in
1998. He is currently Professor at Xi’an Modern Chemistry Research Institute and a
Postdoctoral Researcher in Northwest University.
8