<i>o</i>-Bis(haloorganostannyl)benzenes As Powerful Bidentate Lewis Acids toward Halide Ions

Abstract

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)2P]+ (5) and [o-C6H4(SnClMe2)2·F]-[K·C20H24O6]+ (7) are described. Variable-temperature 119Sn and 19F NMR studies indicate that 2 and 4 act as bidentate Lewis acids toward chloride and fluoride ions exclusively forming the stable anionic 1:1 complexes 5, 7, and [o-C6H4(SnFMe2)2·F]-[Et4N]+ (8). No formation of dianionic 1:2 adducts was observed even with excess of halide ions. The affinity of 2 toward fluoride is greater than toward chloride. Reaction of 2 with HMPA gives the neutral complex o-C6H4(SnClMe2)2·(Me2N)3PO (10), the crystal structure of which is also described.