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* = C6H2tBu3-2,4,6, supermesityl) to
generate Cp*Fe(CO)2E(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 indane-diyl systems of the type (LnM)2EX.

含有带有三配位、卤化物官能化镓或铟给体结构配体的过渡金属配合物，是通过卤原子攫取化学制备[LnM(EX)]⁺型不饱和阳离子物种的关键前驱体。目前已证实两类合成此类三配位体系的路径：(i) 盐消除反应，例如Na[Cp*Fe(CO)₂]与Mes*GaCl₂或Mes*InBr₂反应（其中Mes* = C₆H₂tBu₃-2,4,6，即超均三甲基），可生成Cp*Fe(CO)₂E(Mes*)X（3a：E=Ga，X=Cl；5：E=In，X=Br）；(ii) 先将一卤化镓(I)或一卤化铟(I)插入金属-卤键或金属-金属键中，再在必要时通过位阻庞大的阴离子亲核试剂完成取代反应。晶体学研究证实，无论是在[LnM-E(芳基)X]型的镓基/铟基配合物中，还是在(LnM)₂EX型的卤化物官能化镓烷二基与铟烷二基体系中，目标平面三角形配位的配体结构均已被确认存在。