Synthesis and Characterization of the Monomeric Diaryls M{C₆H₃-2,6-Mes₂}₂ (M = Ge, Sn, or Pb; Mes = 2,4,6-Me₃C₆H₂−) and Dimeric Aryl−Metal Chlorides [M(Cl){C₆H₃-2,6-Mes₂}]₂ (M = Ge or Sn)

Abstract

The reaction of 2 equiv of LiC 6 H 3 -2,6-Mes 2 (Mes = 2,4,6-Me 3 C 6 H 2 −) with GeCl 2 ·dioxane, SnCl 2, or PbCl 2 in ether solution has resulted in the isolation of rare examples of monomeric, σ-bonded, diaryl derivatives M{C 6 H 3 -2,6-Mes 2 } 2 (M = Ge ( 1 ), Sn ( 2 ), or Pb ( 3 )). The compounds 1 − 3 are thermally stable, purple, crystalline solids with V-shaped geometries and remarkably wide ( ca . 114.5°) interligand bond angles. The monoaryl metal chloride derivatives [M(Cl){C 6 H 3 -2,6-Mes 2 }] 2 (M = Ge ( 4 ) or Sn ( 5 )) were isolated by treatment of the appropriate dichlorides with either 1 equiv of LiC 6 H 3 -2,6-Mes 2 or 1 equiv of the diaryls 1 or 2 . The orange germanium compound 4 has a dimeric structure in which the monomers are linked by a relatively weak, 2.443(2) Å, Ge−Ge interaction. In sharp contrast, its yellow tin analogue 5 has a dimeric structure in which three-coordinate tin centers are associated by asymmetrically bridging chlorides. The compounds 1 − 3 constitute a unique, structurally characterized diaryl series for Ge, Sn, and Pb and display evidence of steric crowding that is significantly greater than that observed in previously known σ-bonded diorgano group 14 derivatives. The compounds 4 and 5 are the first fully structurally characterized organometal halide derivatives of Ge or Sn in which the organic ligand is monodentate, purely σ-bonded, and nonchelating.