AB-INITIO CALCULATIONS OF THE TRIGONAL AND ZERO-FIELD SPLITTINGS IN TRISCHELATED DIKETONATO COMPLEXES OF TRIVALENT CHROMIUM

The ground and excited states of the neutral tris(1,3-propacedionato)c hromium(III) d(3) complex an investigated with quantum chemical method s. Trigonal splittings are calculated and compared with experiment for the first two excited quartet states T-4(2g) and T-4(1g). The effect of spin-orbit coupling is also introduced, and a reassignment is propo sed for three absorption bands in the doublet region. Trigonal symmetr y-induced mixing between the e(g) and t(2g) shells is found to be resp onsible for the unusually large zero-field splitting of the T-4(2g) gr ound state. Orbitals pictures are presented which illustrate the role of the phase-coupling effect from the unsaturated ligands.