EXCHANGE AND MAGNETIC DIPOLE-DIPOLE INTERACTIONS IN BIRADICAL AND TRIRADICAL COMPLEXES OF AL(III), GA(III), IN(III), AND SN(IV) WITH O-SEMIQUINONES - PM3 CALCULATION

Semiempirical (PM3 with CI) calculations of exchange interactions for the triradical complexes of Al(III), Ga(III), and In(III) and the bira dical complex of Sn(IV) with o-semiquinones are carried out. The resul ts are in agreement with both qualitative theoretical assumptions and experimental data. The calculations indicate that the superexchange vi a the unoccupied p-orbitals of the central metal ion predominantly det ermines the multiplicity of the ground states of the complexes. Zero-f ield splitting constants D are calculated; they also aaee well with ex perimental data.