title: Multiconfigurational theoretical study of the octamethyldimetalates of Cr(II), Mo(II), W(II), and Re(III): revisiting the correlation between the M-M bond length and the delta --> delta* transition energy.
abstract: Four compounds containing metal-metal quadruple bonds, the [M2(CH3)8]n- ions (M = Cr, Mo, W, Re and n = 4, 4, 4, 2, respectively), have been studied theoretically using multiconfigurational quantum-chemical methods. The molecular structure of the ground state of these compounds has been determined and the energy of the delta --> delta* transition has been calculated and compared with previous experimental measurements. The high negative charges on the Cr, Mo, and W complexes lead to difficulties in the successful modeling of the ground-state structures, a problem that has been addressed by the explicit inclusion of four Li+ ions in these calculations. The ground-state geometries of the complexes and the delta --> delta* transition have been modeled with either excellent agreement with experiment (Re) or satisfactory agreement (Cr, Mo, and W).
authors.affiliation: Dipartimento di Chimica Fisica F. Accascina, Università di Palermo, Viale delle Scienze-Parco d'Orleans II, 1-90128 Palermo, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Ferrante
authors.forename: Laura
authors.initials: L
authors.lastname: Gagliardi
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Bursten
authors.forename: Alfred P
authors.initials: AP
authors.lastname: Sattelberger