Structural, Magnetic and IR Spectroscopic Characterization of Dimeric Copper(II) Trichloroacetate Adduct with Benzonitrile. Nature of the Copper(II)–Bezonitrile Bond

Abstract

Abstract The benzonitrile adduct of copper(II) trichloroacetate, [Cu(Cl3CCOO)2(PhCN)]2, was prepared and characterized. The dimeric structure was confirmed by an X-ray structural determination. This compound crystallizes in the triclinic space group P\bar1 with a=12.780(1), b=16.064(1), c=10.130(1) Å; α=108.39(1), β=113.34(1), γ=81.07(1)°. The crystal consists of two crystallographically independent dimeric units. Both units have the familiar dimeric copper(II) acetate monohydrate structure with Cu–Cu distances of 2.731(1) and 2.732(1) Å. Magnetic susceptibility data in the range of 80–300 K are well represented by the usual dimer equation with a singlet-triplet energy separation of −2J=224 cm−1. The C≡N stretching frequency of benzonitrile in the compound shows an increase by 31 cm−1 from the free ligand value. On the basis of the X-ray crystallographic and IR spectroscopic results, the nature of the copper(II)–benzonitrile bond is discussed. For discussion magnetic and spectroscopic properties of some analogous nitrile adducts of copper(II) chloroacetates were also studied.