EPR AND SPECTRAL STUDIES OF A MOLECULAR AND CRYSTAL-STRUCTURE OF CU(3,5-DIMETHYLPYRIDINE)3(NO3)2

X-band single crystal EPR, IR and UV-VIS data are used to deduce a mol ecular and crystal structure of a new compound with a chemical-formula Cu(3,5-dimethylpyridine)3(NO3)2. EPR shows that four magnetically ine quivalent molecules exist in the crystal unit cell of C4v symmetry. IR spectra suggested that both monodentate and bidentate NO3-groups exis t in the crystal. A most probable Cu(II) complex geometry with d(x2-y2 ) ground state is a square pyramid with three nitrogens from 3,5-dimet hylpyridine molecules and one oxygen from monodentate nitrato group in a basal plane and an oxygen from NO3-group in apical position. There exists a chemical contact between complexes as it is indicated by the exchange interaction with Absolute value of J less-than-or-equal-to 1 cm-1. It suggests that square pyramid complexes are arranged in polyme ric chains with semi-coordination of bidentate NO3-group to the adjace nt Cu(II) ion. An extended analysis of an exchange averaging effect be tween EPR lines from two and four Cu(II) sites is presented with equat ions relating molecular and crystal g-factors.