GROUND TERM SPLITTING OF HIGH-SPIN CO-2+ AS A PROBE OF COORDINATION STRUCTURE .1. DEPENDENCE OF THE SPLITTING ON COORDINATION GEOMETRY
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The sign and magnitude of the splitting between the two lowest Kramers doublets () of high-spin Co2+ in a variety of structurally defined, small molecule coordination complexes is determined. The range of values of is found to be <13 cm-1 in tetracoordinate sites, ~20-50 cm-1 in pentacoordinate sites of trigonal-bipyramidal or square-pyramidal geometry, and 50 cm-1 in hexacoordinate sites. It is shown on the basis of group theoretical arguments and estimates of the zero-field splitting derived by second-order perturbation theory that the observed range of values of correlates well with that predicted by theory. On this basis, it is suggested that the splitting between the two lowest Kramers doublets of high-spin Co2+ may provide a diagnostic signature of coordination geometry. 1985, American Chemical Society. All rights reserved.