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)(mu-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 pi-bonding character; in contrast, the indium-bridged complex 8 is shown to feature a much smaller pi component to the metal-ligand interaction. Analogous reactions utilizing the supermesityl-substituted gallyl or indyl precursors of the type (eta(5)-C5R5)Fe(CO)(2)E(Mes*)X, on the other hand, lead to the synthesis of halide-bridged species of the type [{(eta(5)-C5R5)Fe(CO)(2)E(Mes*)}(2)(mu-X)](+), presumably by trapping of the highly electrophilic putative cationic diyl complex [(eta(5)-C5R5)Fe(CO)(2)E(Mes*)](+).