Cyanamidonitrate-copper(II) complexes of imidazole ligands: X-ray crystallography and physical investigation

New cyanamidonitrate-copper(II) complexes [Cu(NO2NCN)(2)L-n] (L = imidazole (iz), n = 2; L = iz, 1-, 2- or 4-methylimidazole (meiz), n = 4) have been isolated and characterised by IR, electronic and ESR spectroscopy. The crys tal structures of 1- and 4-meiz complexes have been determined by X-ray cry stallography; the structure of [Cu(NO2NCN)(2)(iz)(2)] is known (J. Kozisek, J.G. Diaz, M. Hvastijova, L. Jager, Acta Crystallogr., Sect. C53 (1997) 70 3) The crystal structure of the first two compounds consists of [Cu(NO2NCN) (2)L-4] units, in which the central Cu-II atoms are pseudo-octahedrally coo rdinated by six nitrogen atoms. Four of them, in equatorial planes, origina te from meiz molecules and two, in axial positions, are nitrile nitrogens f rom the NO2NCN- anions. Influence of hydrogen bonds on equatorial-axial bon d length correlation was ascertained. Tn the ESR spectra of the [Cu(NO2NCN) (2)L-4] compounds copper hyperfine splitting is resolved. For all complexes , weak lines corresponding to the Delta M-s = 2 transitions appear. The spe ctrum of [Cu(NO2NCN)(2)(iz)(4)] in frozen methanolic solution shows 16-fold nitrogen splitting of the perpendicular band. (C) 1999 Elsevier Science S. A. All rights reserved.