The Interplay Between Metal-Metal Bonds, Four-Electron Donor Carbonyl Groups, and Five-Electron Donor Nitrosyl Groups in Highly Unsaturated Binuclear Rhenium Carbonyl Nitrosyls

摘要

Optimization of structures for the highly unsaturated binuclear rhenium carbonyl nitrosyls Re-2(NO)(2)(CO)(n) (n = 5, 4) using the MPW1PW91 and BP86 methods of density functional theory indicate complicated potential energy surfaces with eight singlet and three triplet energetically accessible structures for Re-2(NO)(2)(CO)(5) and 11 singlet and six triplet energetically accessible structures for Re-2(NO)(2)(CO)(4). The lowest energy structure for Re-2(NO)(2)(CO)(5) is a singlet predicted to have two bridging nitrosyl groups and a formal Re Re triple bond to give both rhenium atoms the favored 18-electron configuration. However, other relatively low-energy structures for Re-2(NO)(2)(CO)(5) are found with five-electron donor bridging nitrosyl groups, four-electron donor bridging carbonyl groups, and coordinatively unsaturated rhenium.