o-bis(haloorganostannyl)benzenes as powerful bidentate Lewis acids toward halide ions

The synthesis of the o-phenylene-bridged ditin species o-C6H4(SnXMe2)(2) (2 , X = Cl; 4, X = F) and o-C6H4(SnCl2Me)(2) (3) is reported and the crystal structures of [o-C6H4(SnClMe2)(2). Cl](-)[(Ph3N)(2)P](+) (5) and [o-C6H4(Sn ClMe2)(2). F](-)[K . C20H24O6](+) (7) are described. Variable-temperature S n-119 and F-19 NMR studies indicate that 2 and 4 act as bidentate Lewis aci ds toward chloride and fluoride ions exclusively forming the stable anionic 1:1 complexes 5, 7, and [o-C6H4(SnFMe2)(2). F](-)[Et4N](+) (8). No formati on of dianionic 1:2 adducts was observed even with excess of halide ions. T he affinity of 2 toward fluoride is greater than toward chloride. Reaction of 2 with HMPA gives the neutral complex o-C6H4(SnClMe2)(2).(Me2N)(3)PO (10 ), the crystal structure of which is also described.