X-band e.p.r. spectra of polycrystalline, polynuclear complexes of the type
[(dien)Cu-im-Cu(dien)](n)(ClO4)(n) and [(dien)Cu-imH-Cu(dien)](n)(ClO4)(2n
) are described, where dien = diethylenetriamine, imH and im are imidazole
(and 2-methyl- and 2-ethylimidazole) respectively. All the complexes show e
.p.r. spectra characteristic of S = 1, which yield the value of the zero fi
eld splitting parameter, D, in the 0.030 +/- 0.001 cm(-1) range.