Abstract
The title compound, [Cu2Cl4(C5H10N2O2)2(CH3CN)2] or [Cu2(μ2-Cl)2(CH3-Pz-COOCH2CH3)2Cl2(CH3CN)2], was synthesized using a one-pot reaction of copper powder, copper(II) chloride dihydrate and ethyl 5-methyl-1H-pyrazole-3-carboxyl-ate (CH3-Pz-COOCH2CH3) in aceto-nitrile under ambient conditions. This complex consists of discrete binuclear mol-ecules with a {Cu2(μ2-Cl)2} core, in which the Cu⋯Cu distance is 3.8002 (7) Å. The pyrazole-based ligands are bidentate coordinated, leading to the formation of two five-membered chelate rings. The coordination geometry of both copper atoms (ON2Cl3) can be described as distorted octa-hedral on account of the aceto-nitrile coordination. A Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from H⋯H (40%), H⋯Cl/Cl⋯H (24.3%), H⋯O/O⋯H (11.8%), H⋯C/C⋯H (9.2%) and H⋯N/N⋯H (8.3%) inter-actions.
Highlights
Chemical contextPyrazoles can form structures of various nuclearities, ranging from mononuclear (Mighell et al, 1975; Liu et al, 2001; Małecka et al, 2003) to polynuclear complexes (He, 2011; Contaldi et al, 2009; Chandrasekhar et al, 2008) and metallacycles (Vynohradov et al, 2020a; Surmann et al, 2016; Galassi et al, 2012) with specific molecular topologies
A Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from HÁ Á ÁH (40%), HÁ Á ÁCl/ClÁ Á ÁH (24.3%), HÁ Á ÁO/OÁ Á ÁH (11.8%), HÁ Á ÁC/CÁ Á ÁH (9.2%) and HÁ Á ÁN/NÁ Á ÁH (8.3%) interactions
Considering the above, we understand the importance of accumulating a theoretical information base on such coordination compounds, and in this article we report the synthesis, crystal structure and Hirshfeld surface analysis of a new binuclear copper(II) complex with unsymmetrical pyrazole ethyl 5-methyl-1H-pyrazole-3-carboxylate – [Cu2(2Cl)2(CH3-Pz-COOCH2CH3)2Cl2(CH3CN)2]
Summary
Pyrazoles can form structures of various nuclearities, ranging from mononuclear (Mighell et al, 1975; Liu et al, 2001; Małecka et al, 2003) to polynuclear complexes (He, 2011; Contaldi et al, 2009; Chandrasekhar et al, 2008) and metallacycles (Vynohradov et al, 2020a; Surmann et al, 2016; Galassi et al, 2012) with specific molecular topologies. The asymmetric unit consists of one copper ion, one ethyl 5-methyl-1H-pyrazole-3-carboxylate ligand, one coordinated acetonitrile molecule and two chlorine ions. One of these chlorine ions bridges two metal centers, connecting two symmetry-generated fragments. The structure of this complex can be described as a dimer of formula [CuCl2(C7H10N2O2)(CH3CN)]2 in which the CH3-Pz-COOCH2CH3 ligand is coordinated in a bidentate way and remains protonated. The copper atom has a distorted octahedral coordination environment formed by three chlorine atoms, one nitrogen atom of the acetonitrile molecule and two atoms of the unsymmetrical pyrazole ligand – the pyridine-like N1 atom and atom O 1 of the ester substituent in position 3 of the pyrazole ring. The molecular structure is stabilized by intramolecular N—HÁ Á ÁCl and C—HÁ Á ÁCl hydrogen bonds (Table 1)
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