Cobalt analogues of Roussin's red salt esters: a density functional study

摘要

Density functional theory calculations on the Co2(NO)4(SR)2 compounds (R = CH3, CF3 and C4H9) predict butterfly and open isomeric structures with and without a direct Co-Co bond. The open Co2(NO)4(SR)2 structures are favored over the butterfly isomers, in terms of relative energy. Furthermore the open structures are predicted to have approximately twice as large HOMO-LUMO gaps than the butterfly Co2(NO)4(SR)2 isomers. For the related Co2(CO)6(SR)2 species, competing open and butterfly structures with similar HOMO-LUMO gaps were predicted. This could explain why the Co2(NO)4(μSR)2 compounds have already been synthesized and why no genuine Co2(CO)6(SR)2 derivatives have yet been reported.