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Journal of Structural Chemistry. Vol. 54, No. 5, pp. 986-989, 2013
Original Russian Text Copyright © 2013 by Yu. M. Chumakov, T. B. Capatina, P. Petrenko, V. I. Tsapkov, A. P. Gulea
CRYSTAL STRUCTURE OF TETRA(µ-ACETATO)bis{[1-ETHYL-3-(PYRIDINE-2-YL)CARBAMIDE]COPPER}
© Yu. M. Chumakov,1 T. B. Capatina,2 P. Petrenko,1
V. I. Tsapkov,2 and A. P. Gulea2
The
crystal
structure
of
UDC 548.736:541.49:546.732:546.742
tetra(μ-acetato)-bis{[1-ethyl-3-(pyridine-2-yl)carbamide]copper}
Cu2(L)2(CH3COO)4 (I), where L is 1-ethyl-3-(pyridine-2-yl)carbamide, is determined. The asymmetric unit
cell of the crystal structure of I contains a copper complex with two acetate ions and a monodentate
molecule of 1-ethyl-3-(pyridine-2-yl)carbamide, which is coordinated via the pyridine nitrogen atom. Due
to the symmetry center, binuclear complexes form in the crystal, in which the acetate ions act as bridges
between the metal atoms. In them, the coordination polyhedron of the central copper atoms represents an
almost ideal tetragonal pyramid. Its base is formed from the oxygen atoms of acetate ions. In the crystal of
the binuclear complex, hydrogen bonds form between the acetate ions and the L ligand along with an
intramolecular hydrogen bond, which stabilize the conformation of the organic L molecule. Between the
neighboring complexes in the crystal, the van der Waals interaction occurs.
DOI: 10.1134/S0022476613050235
Keywords: 3d metal complexes, single crystal X-ray diffraction study, carbamide derivatives.
Metal carboxylates occur in numerous natural objects and find a wide application in different areas of human
activity. Being a constituent of metalloproteins and other biomolecules, these compounds provide the critical biochemical
functions of living organisms and determine the behavioral patterns of many enzymes and antibodies, and also the specificity
of the interaction between intra- and extracellular structures [1, 2]. Polynuclear carboxylate complexes are often used as
model systems in the study of biological processes [3, 4]. In many cases, the properties of these substances are in good
agreement with their composition and structure. For this reason, the determination of the optimal conditions for producing and
studying the structure of new representatives of this class of chemical compounds are both of scientific and practical interest.
The purpose of this work is the synthesis and determination of the structural features of tetra(μ-acetato)-bis{[1ethyl-3-(pyridine-2-yl)carbamide]copper} Cu2(L)2(CH3COO)4 (I), where L is 1-ethyl-3-(pyridine-2-yl)carbamide.
Experimental. Compound I was obtained using the following technique: to a suspension containing 10 mmol of
Cu2(CH3COO)4⋅2H2O in 30 ml of ethanol under stirring and heating in a water bath (50-55°C) a solution containing 20 mmol
of 1-ethyl-3-(pyridine-2-yl)carbamide in 20 ml of ethanol is added. Therewith, a dark green solution forms, from which after
1
Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau. 2Moldova State University, Chisinau;
[email protected]. Translated from Zhurnal Strukturnoi Khimii, Vol. 54, No. 5, pp. 947-949, September-October, 2013.
Original article submitted November 1, 2012.
986
0022-4766/13/5405-0986
slow evaporation for 24 h a fine crystalline substance (yield 60%) precipitates, which is filtered off on a glass filter, washed
with a small amount of ethanol and ether, and dried in the air. The composition of the substance was determined based on the
data of elemental analysis. Found, %: C 41.37, H 4.81, Cu 18.15, N 11.90. For C24H34Cu2N6O10 calculated, %: C 41.55, H
4.95, Cu 18.32, N 12.12.
Compound I is well soluble in dimethylformamide and dimethylsulfoxide and soluble in water and alcohols on
heating. Its single crystals suitable for the X-ray diffraction study were obtained by recrystallization of the studied substance
from ethanol.
The single crystal X-ray diffraction study of complex I was performed on an Xcalibur Oxford Diffraction
diffractometer [5]. The structure was solved by a direct method and refined by the least-square method in the anisotropic
approximation for non-hydrogen atoms using the SHELX-97 software [6]. Hydrogen atoms were included in the refinement
in geometrically calculated positions, and their thermal factors UH were set in 1.2 times larger than those for carbon and
oxygen atoms linked with them. The coordinates of the basic atoms in the studied structures were deposited with the
Cambridge Structural Database (CCDC 891978). In order to perform the geometric calculations and make the figures, the
PLATON software was used [7]. For the analysis of the obtained structures, the Cambridge Structural Database (version
5.30) was used [8, 9]. The main parameters of the experiment, structure solution and refinement are as follows:
C24H34Cu2N6O10, sample of 0.30×0.20×0.10 mm in size, MoKα radiation, λ = 0.71073 Å, M = 693.67, triclinic crystals, space
group P-1, a = 7.6229(4) Å, b = 8.4845(5) Å, c = 11.7430(7) Å, α = 84.424(5)°, β = 85.078(4)°, γ = 76.876(5)°, V =
734.57(7) Å3; Z = 8, ρcalc = 1.568 g/cm–3, μ = 1.511 mm–1, 5183 measured reflections (θmax = 25.50°), of which 2737
independent, 2446 with I > 2σ(I ), 193 refined parameters, for I > 2σ(I ) R1 = 0.0421 and wR2 = 0.1003, Δρ (max/min) =
0.521/–0.708 e/Å3.
Results and discussion. The asymmetric unit of the crystal structure of I contains the coordination compound of
copper with a monodentate molecule of 1-ethyl-3-(pyridine-2-yl)carbamide and two acetate ions. Due to the symmetry
center, the binuclear complexes form in the crystal, in which the acetate ions act as bridges between the metal atoms (Fig. 1).
Therewith, the Cu(1)–Cu(1)a distance is 2.644 Å. In the studied compound, the coordination polyhedron of the copper atoms
represents an almost ideal tetragonal pyramid, which is also confirmed by the calculation of the τ index suggested in [10]:
τ = (β – α)/60, where α (167.69°) and β (167.23°) are the largest angles between the bonds formed by the central atom. If τ is
0, then the metal coordination is described as an ideal tetragonal pyramid, and with τ of 1 it is described as an ideal tetragonal
bipyramid. In I, the τ values are 0.01, and this allowed us to make the above conclusion on the coordination of the copper
atoms. The base of tetragonal pyramids of the metal atoms in the studied binuclear complex is formed of the oxygen atoms of
the acetate ligands; the deviations of these atoms from the mean planes determined by them do not exceed 0.005 Å. The
deviation of the copper atoms from these planes to the N(1) and N(1)a nitrogen atoms occupying the apical vertices of the
coordination pyramids is 0.214 Å. Therewith, the Cu(1)–N(1) distance is 2.269(2) Å. In the compound under study, the
angles formed by these bonds with the atoms of the base of tetragonal pyramids are in a range of 95.1-97.6°. The lengths of
the metal bonds with the donor atoms of the tetragonal pyramid base are as follows: Cu(1)–O(1) 1.973(2) Å, Cu(1)–O(2)
1.960(2) Å, Cu(1)–O(3) 1.954(2) Å, Cu(1)–O(4)a (–x+2, –y, –z) 1.957(2) Å. The volumes of coordination pyramids of the
Cu1 atom in the binuclear complex are 6.302 Å3.
In the crystal in the binuclear complex, between the acetate ligands and the L ligand the N(2)–H(1)…O(1), C(5)–
H(14)…O(4)a hydrogen bonds form along with an intramolecular C(8)–H(4)…O(5) hydrogen bond (Table 1, Fig. 1), which
stabilize the conformation of the organic L molecule. Thus, the angle between the (Cu(1)O(1)N(1)N(2)C(9)H(1)) and
(Cu(1)O(4)a N(1)C(5)H(14)) metal rings is 1.1°, and the deviations of the (O(5)N(1)N(2)N(3)C(5)÷C(12)) atoms from the
mean plane determined by them do not exceed 0.08 Å. Between the binuclear complexes in the crystal, the van der Waals
interaction occurs (Fig. 2).
Therefore, the study showed that the reaction of copper(II) diacetate hydrate with 1-ethyl-3-(pyridine-2yl)carbamide in hot ethanol does not lead to the destruction of the dimeric structure of acetate, but ends up with the
987
Fig. 1. Atom numbering in the binuclear complex of compound I.
Fig. 2. Packing fragment of compound I in the crystal.
TABLE 1. Geometric Parameters of Hydrogen Bonds for Compound I
D–H⋯A bond
N(2)–H(1)⋯O(1)
C(8)–H(4)⋯O(5)
C(5)–H(14)⋯O(4)
988
D–H
Distance, Å
H⋯A
D⋯A
0.86
0.93
0.93
1.95
2.28
2.36
2.802(3)
2.875(4)
3.035(4)
DHA ange, deg
Coordinates
of A atom
170
122
130
x, y, z
x, y, z
2–x, –y, –z
carbamide substitution for intraspheric water and the formation of tetra(μ-acetato)-bis{[1-ethyl-3-(pyridine-2yl)carbamide]copper} Cu2(L)2(CH3COO)4.
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