MAGNETIC AND SPECTRAL PROPERTIES OF THE PENTAGONAL-BIPYRAMIDAL COMPLEX-IONS CHLOROAQUA AND DIAQUA[2,6-DIACETYLPYRIDINE BIS-(SEMICARBAZONE)]COBALT(II)

Principal crystal susceptibilities throughout the temperature range 10-300 K have been measured for the complexes [Co(DAPSC)Cl,H2O]+Cr-2H2O and [Co(DAPSC)(H2O)2]2+(NO3-)2-H2O, where DAPSC = 2, 6-diacetylpyridine bis-(semicarbazone). Unpolarized, single-crystal transmission spectra have been recorded in the UV, visible, and near-IR regions. For each complex independently, the spectral and magnetic properties have been quantitatively and simultaneously reproduced within the angular overlap model (aom). Spectral bands in the 15 000-18 000-cm-1 region are assigned to components of the 4P manifold. Ligand field, aom parameters accurately reproducing spectral features and all magnetic properties all appear chemically sensible, commenting upon the normality of the axial bonds in these pentagonal-bipyramidal complexes and on the σ-bond characteristics of the keto group. Small differences in the spectra and magnetism of the diaqua and chloroaqua complexes are uniquely associated with a lesser π-donor ability of water with respect to chlorine. © 1979, American Chemical Society. All rights reserved.