Abstract
New cyanamidonitrate–copper(II) complexes [Cu(NO
2NCN)
2L
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 crystal structures of 1- and 4-meiz complexes have been determined by X-ray crystallography; the structure of [Cu(NO
2NCN)
2(iz)
2] is known (J. Kožı́šek, J.G. Dı́az, M. Hvastijová, L. Jäger, Acta Crystallogr., Sect. C 53 (1997) 703). The crystal structure of the first two compounds consists of [Cu(NO
2NCN)
2L
4] units, in which the central Cu
II atoms are pseudo-octahedrally coordinated by six nitrogen atoms. Four of them, in equatorial planes, originate from meiz molecules and two, in axial positions, are nitrile nitrogens from the NO
2NCN
− anions. Influence of hydrogen bonds on equatorial–axial bond length correlation was ascertained. In the ESR spectra of the [Cu(NO
2NCN)
2L
4] compounds copper hyperfine splitting is resolved. For all complexes, weak lines corresponding to the Δ
M
s=2 transitions appear. The spectrum of [Cu(NO
2NCN)
2(iz)
4] in frozen methanolic solution shows 16-fold nitrogen splitting of the perpendicular band.