Nature of M–E Bonds in Metallosilylenes, -germylenes, -stannylenes, and -plumbylenes [(η⁵-C₅H₅)(Me₃P)(H)₂M(EPh)] (M = Fe, Ru, Os; E = Si, Ge, Sn, Pb)

Abstract

Geometry, electronic structure, and bond energy analysis of M–ER bonds in the terminal metallosilylenes, metallogermylenes, metallostannylenes, and metalloplumbylenes of iron, ruthenium, and osmium [(η 5 -C 5 H 5 )(Me 3 P)(H) 2 M(EPh)] ( I, M = Fe, E = Si; II, M = Fe, E = Ge; III, M = Fe, E = Sn; VI, M = Fe, E = Pb; V, M = Ru, E = Si; VI, M = Ru, E = Ge; VII, M = Ru, E = Sn; VIII, M = Ru, E = Pb; IX, M = Os, E = Si; X, M = Os, E = Ge; XI, M = Os, E = Sn; XII, M = Os, E = Pb) were investigated at the DFT/BP86/TZ2P/ZORA level of theory. The M–E bonds in these complexes are essentially M–E single bonds. In all studied complexes, the π-bonding contribution to the total M–EPh bond is significantly smaller than that of the σ-bonding and increases upon going from M = Fe to Os. Thus, in the EPh ligands the E atom is predominantly a σ-donor. The nature of E has a significant effect on the M–P bonding to the Me 3 P ligand trans to EPh. The M–P bond distances decrease upon going from SiPh to PbPh. The contributions of the electrostatic interactions Δ E elstat to the M–EPh bonds are larger in all complexes I – XII than the covalent bonding Δ E orb . The M–E bond in each case has a degree of covalent character of between 36% and 48%. In contrast to the interaction between charged fragments, where the electrostatic interactions Δ E elstat are greater that the orbital interactions Δ E orb, the orbital interactions Δ E orb are larger than the electrostatic interactions Δ E elstat for interaction between neutral fragments. In the case of homolytic bond dissociation, the M–E bond in each case has a degree of covalent character of between 56% and 64%.