Transition‐Metal Complexes [(PMe3)2Cl2M(E)] and [(PMe3)2(CO)2M(E)] with Naked Group 14 Atoms (E=C–Sn) as Ligands; Part 2: Complexation with W(CO)5

Density functional calculations at the BP86/TZ2P level were carried out to understand the ligand properties of the 16‐valence‐electron(VE) Group 14 complexes (PMe₃)₂Cl₂M(E)] ( 1ME ) and the 18‐VE Group 14 complexes (PMe₃)₂(CO)₂M(E)] ( 2ME ; M=Fe, Ru, Os; E=C, Si, Ge, Sn) in complexation with W(CO)₅. Calculations were also carried out for the complexes (CO)₅W–EO. The complexes (PMe₃)₂Cl₂M(E)] and (PMe₃)₂(CO)₂M(E)] bind strongly to W(CO)₅ yielding the adducts 1ME–W(CO)₅ and 2ME–W(CO)₅ , which have C_2v equilibrium geometries. The bond strengths of the heavier Group 14 ligands 1ME (E=Si–Sn) are uniformly larger, by about 6–7 kcal mol^?1, than those of the respective EO ligand in (CO)₅W‐EO, while the carbon complexes 1MC–W(CO)₅ have comparable bond dissociation energies (BDE) to CO. The heavier 18‐VE ligands 2ME (E=Si–Sn) are about 23–25 kcal mol^?1 more strongly bonded than the associated EO ligand, while the BDE of 2MC is about 17–21 kcal mol^?1 larger than that of CO. Analysis of the bonding with an energy‐decomposition scheme reveals that 1ME is isolobal with EO and that the nature of the bonding in 1ME–W(CO)₅ is very similar to that in (CO)₅W–EO. The ligands 1ME are slightly weaker π acceptors than EO while the π‐acceptor strength of 2ME is even lower.