Activation of M—H bond upon the complexation of transition metal hydrides with acids and bases

Features of the electronic structure of adducts of transition metal hydride complexes (Cp*M(dppe)H, dppe is the 1,2-(diphenylphosphino)ethane, M = Fe, Ru, Os; CpM(CO)3H, M = Mo, W) with acids and bases were analyzed with the ADF2014 program using energy decomposition analysis (EDA) by the Ziegler-Rauk method combined with the natural orbitals for chemical valence theory (ETS-NOCV). The nature of orbital interactions in the complex determines the reaction pathway: σMH → σ*OH interaction leads to the proton transfer to hydride ligand, nM → σ*OH leads to the metal atom protonation, nN → σ*MH implies the metal hydride deprotonation, and σMH → n*B corresponds to the hydride transfer to Lewis acid. It was shown that M-H bond polarization change has the similar character upon the formation of complexes with Brønsted and Lewis acids. The ease of polarization of M-H bonds in complexes CpM(CO)3H determines their reactivity as proton and hydride ion donors.