Dative quadruple bonds between d¹⁰ transition metals and beryllium in BeM(PMe₃)₂ and BeM(CO)₂ (M = Ni, Pd, and Pt) complexes: Transition metal fragments as six‐electron donor and two‐electron acceptor

Abstract

The structure, chemical bonding, and reactivity of neutral 16 valence electrons (VE) transition metal complexes of beryllium, BeM(PMe3)2 (1M‐Be) and BeM(CO)2 (2M‐Be, M = Ni, Pd, and Pt) were studied. The molecular orbital and EDA‐NOCV analysis suggest dative quadruple bonds between the transition metal and beryllium, viz., one Be→M σ bond, one Be←M σ bond, and two Be←M π bonds. The strength of these bonding interactions varies based on the ligands coordinated to the transition metal. The Be←M σ bond is stronger than the Be→M σ bond when the ligand is PMe3, whereas the reverse order is observed when the ligand is CO. This is attributed to the higher π acceptor strength of CO as compared to PMe3. Since these complexes have M–Be dative quadruple bonds, the beryllium center is susceptible to ambiphilic reactivity, as indicated by high proton and hydride affinity values.