THE QUANTITATIVE INTEPRETATION OF A/D PARAMETERS FOR ELECTRONIC EXCITATION MO ASSIGNMENTS OF TRANS-[M(CO)4(P(n-Bu)3)2] (M = Cr, Mo, AND W) BASED ON ELECTRONIC MCD AND COMPLETE OPERATOR MATRIX 〈Lz〉 EVALUATION

Abstract

Abstract Electronic absorption (EA) and magnetic circular dichroism (MCD) spectra of trans-[M(CO)4(P(n-Bu)3)2] (M = Cr, Mo, W) of five bands from ∼20.0 × 103 to ∼45.5 × 103 cm−1 were measured. The EA spectra exhibit three dominant bands, I-III, at about 27 × 103 cm−1, 30 × 103 cm−1, and 39 × 103 cm−1, respectively. Corresponding MCD spectra in the region of both hands I and III are dominated by the presence of positive A-terms, indicative of transitions to degenerate excited states. A-terms and dipole strength (D) parameters were extracted by rigorous spectral deconvolution for the Cr complex; the spectra of the Mo and W analogs are quite similar. Since these are charge transfer bands and a number of the 2-center and 3-center integrals of 〈Lz〉 will be large, multi-zeta all-center operator matrix computations were used to evaluate signs and magnitudes of MCD A/D parameters for all degenerate excited-state electronic configurations of statically electric dipole allowed g → u (MLCT, or ·M → π∗(CO)) type tran...