Toward cationic gallane- and indanediyl complexes: Synthetic approaches to three-coordinate halogallyl and -indyl precursors

Transition metal complexes containing ligands featuring three-coordinate, halide-functionalized gallium or indium donors represent key precursors to unsaturated cationic species of the type [LnM(EX)](+) via halide abstraction chemistry. Two routes to these three-coordinate systems have been demonstrated: (i) salt elimination, such as the reaction between Na[CP*Fe(CO)(2)] and Mes*GaCl2 or Mes*InBr2 (Mes* = (C6H2Bu3)-Bu-t-2,4,6, supermesityl) to generate Cp*Fe(CO)(2)E(Mes*)X (3a, E = Ga, X = Cl; 5, E = In, X = Br), and (ii) insertion of a gallium(I) or indium(I) halide into a metal-halogen or metal-metal bond followed, where necessary, by substitution by a sterically bulky anionic nucleophile. Crystallographic studies have confirmed the presence of the target trigonal planar ligand systems both in gallyl/indyl complexes of the type LnM-E(Aryl)X and in halide-functionalized gallane- and indanediyl systems of the type (LnM)(2)EX.