Electronic absorption spectra of Mo2(O2CCF3)4 and Mo2(O2CH)4 have been measured at 10 K in inert matrices. Results are compared with previous studies of Mo2(O2CCH3)4. Raman spectra of the three carboxylate complexes have been measured and assigned. Unlike Mo2Cl8 4- or Re2Cl8 2- resonance enhancement of the metal-metal stretch did not occur when the lowest energy absorption band was irradiated; preresonance enhancement of a carboxylate stretching vibration did occur. Certain aspects of the SCF-Xα-DV calculations for Mo2(O2CH)4 agree better with previous HF calculations than with SCF-Xα-SW results. The sensitivity of the π-π* separation to metal-metal distance may explain these differences. Energies of both the singlet and triplet δ → δ*, δ → π*, σ → δ*, and δ → π* (OCO) transitions have been calculated and compared with the optical spectra.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry