EPR and Spectral Studies of a Molecular and Crystal Structure of Cu (3,5-dimethylpyridine)3(NO3)2
S.K. Hoffmanna, M.A.S. Goherb, W. Hilczera, J. Goslara and A.K. Hafezb
aInstitute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17/19, 60-179 Poznań, Poland
bUniversity of Alexandria, Department of Chemistry, Alexandria 21321-Ibrahimia, Egypt
Received: October 22, 1993
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X-band single crystal EPR, IR and UV-VIS data are used to deduce a molecular and crystal structure of a new compound with a chemical formula Cu(3,5-dimethylpyridine)3(NO3)2. EPR shows that four magnetically inequivalent molecules exist in the crystal unit cell of C4v symmetry. IR spectra suggested that both monodentate and bidentate NO3-groups exist in the crystal. A most probable Cu(II) complex geometry with dx²-y² ground state is a square pyramid with three nitrogens from 3,5-dimethylpyridine 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 |J| ≤ 1 cm-1. It suggests that square pyramid complexes are arranged in polymeric chains with semi-coordination of bidentate NO3-group to the adjacent Cu(II) ion. An extended analysis of an exchange averaging effect between EPR lines from two and four Cu(II) sites is presented with equations relating molecular and crystal g-factors.
DOI: 10.12693/APhysPolA.85.517
PACS numbers: 33.20.Ea, 61.66.-f, 76.30.Da