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 LiC6H3-2,6-Mes2 (Mes = 2,4,6-Me3C6H2−) with GeCl2·dioxane, SnCl2, or PbCl2 in ether solution has resulted in the isolation of rare examples of monomeric, σ-bonded, diaryl derivatives M{C6H3-2,6-Mes2}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){C6H3-2,6-Mes2}]2 (M = Ge (4) or Sn (5)) were isolated by treatment of the appropriate dichlorides with either 1 equiv of LiC6H3-2,6-Mes2 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.

Mechanistic Study of Stepwise Methylisocyanide Coupling and C–H Activation Mediated by a Low-Valent Main Group Molecule

“…27 We now report the isolation and structural characterization of a series of compounds arising from the insertion reactions of the simplest isocyanide, MeNC, with the germylene Ge(Ar Me 6) 2 (Ar Me 6 = C6H3-2,6(C6H2-2,4,6-Me3)2) 28 and supply details of the mechanism of the subsequent transformation. We show that the simple adduct (Ar Me 6) 2GeCNMe (1), is formed in the first instance, whereupon the coordinated methylisocyanide molecule in 1 then undergoes a spontaneous migratory insertion into one of the Ge -C(Ar) bonds to form the structural isomer (Ar Me 6)Ge(μ-CNMe)(Ar Me 6) (1′ in hexane (20 mL) methylisocyanide (5 mmol) was added at room temperature.…”

Heteroleptic lead(II)-halide complexes supported by a bulky iminoanilide ligand

“…Terphenyls have for instance yielded the encumbered two-coordinate [Pb{Ar'} 2 ] (Simons et al, 1997) and [{Ar'}PbSi(SiMe 3 ) 3 ] (Klett et al, 1999) where Ar' = C 6 H 3 Mes 2 -2,6, the halo-bridged dimers [{Ar''}Pb(μ-Br)] 2 (Pu et al, 2000) and [{Ar''}Pb(μ-I)] 2 (Filippou et al, 2004) where Ar'' = C 6 H 3 Trip 2 -2,6, and the two-coordinate organolead(II) compounds [{Ar''}PbR] for R = Me, t Bu or Ph (Pu et al, 2000). (Jana et al, 2011).…”

Synthesis, Structure, and Reactivity of Kinetically Stabilized Low-coordinated Organolead Compounds.

“…The Pb-C bond length (7)1 is one of the widest among stable plumbylenes (ref. [4][5][6][7][8][9][10][11] and much wider than that theoretically predicted for dimethylplumbylene [93.01 owing to the steric repulsion of two bulky T'bt groups. The longer Pb-C bond lengths of plumbylene 9a compared with those of usual tetravalent organolead compounds are attributable not only to the steric repulsion between the substituents on the lead atom but also to the .…”