Halide Abstraction as a Route to Cationic Transition-Metal Complexes Containing Two-Coordinate Gallium and Indium Ligand Systems

Halide abstraction chemistry offers a viable synthetic route to the cationic two-coordinate complexes [{Cp*Fe(CO)2}2(μ-E)]+ (7, E = Ga; 8, E = In) featuring linear bridging gallium or indium atoms. Structural, spectroscopic, and computational studies undertaken on 7 are consistent with appreciable Fe−Ga π-bonding character; in contrast, the indium-bridged complex 8 is shown to feature a much smaller π component to the metal−ligand interaction. Analogous reactions utilizing the supermesityl-substituted gallyl or indyl precursors of the type (η5-C5R5)Fe(CO)2E(Mes*)X, on the other hand, lead to the synthesis of halide-bridged species of the type [{(η5-C5R5)Fe(CO)2E(Mes*)}2(μ-X)]+, presumably by trapping of the highly electrophilic putative cationic diyl complex [(η5-C5R5)Fe(CO)2E(Mes*)]+.