Dcab2--Substituted Manganese Vinylidene Complexes as Better Electron Reservoirs: A DFT Study

Abstract

Mononuclear vinylidene complexes of the type Mn(C5H4R‘)(R‘ ‘2PCH2CH2P R‘ ‘2)CC(R1)(H) are synthesized and reported by Venkatesan et al. as potential electron reservoirs, which can store and release electrons in a reversible fashion. However, the slow oxidation of the parent compound leads to an undesired product. In our model compound Mn(C5H5)(PH3)2CC(R)(H), we substituted the cyclopentadienyl moiety by the isolobal dianionic dicarbollyl ligand Dcab2- (C2B9H112-) and investigated whether this simple substitution can reduce the production of an undesired product. Our calculations of vertical electron detachment energy, thermodynamic feasibility, and molecular orbital analysis (with substituents R = H, Me, Ph on the Cβ atom of our model system) show that the substitution is thermodynamically favorable and leads to easy oxidation of the parent compound, easy dimerization, and better reversibility. Our comparative study between Mn(C5H5)(PH3)2CC(R)(H) and Mn(Dcab)(PH3)2CC(R)(H)- (where R = H, Me, Ph) predicts the latter to be a better electronic reservoir.