Reactivity of 2,6‐Dihalophenyl Lithium Reagents Towards Chlorosilanes. Synthesis and Structure of 2,3‐ and 2,6‐Dihalophenyl(di‐)silanes

Abstract

The reaction of 2,6-dihalophenyllithium 2,6-X 2 C 6 H 3 Li (X = F, Cl, Br) with the chlorosilanes ClMe 2 SiSiCl 2 Me, SiCl 4 , and HSiCl 3 afforded the diaryldisilanes (2,6-X 2 C 6 H 3 SiMe 2 ) 2 [X = F (1a), Cl (1b), Br (1c)] and the diaryl-and triarylsilanes (2,6-X 2 C 6 H 3 ) 2 SiCl 2 [X = F (3a), Cl (3a)], (2,3-Br 2 C 6 H 3 ) 2 SiCl 2 (4c), (2,6-F 2 C 6 H 3 ) 3 SiH (6a), and (2,6-X 2 C 6 H 3 ) 2 Si(H)Cl [X = Cl (7b), Br (7c)], respectively. The formation of 4c was rationalized on the basis of an equilibrium that exists * Prof. Dr. J. Beckmann E-Mail: j.beckmann@uni-bremen.de [a] 1034 between the aryllithium isomers 2,6-Br 2 C 6 H 3 Li and 2,3-Br 2 C 6 H 3 Li . Reduction of 3a, 3b, 4c, 7b, and 7c using LiAlH 4 provided the diarylsilanes (2,6-X 2 C 6 H 3 ) 2 SiH 2 [X = F (2a), Cl (2b), Br (2c)] and (2,3-Br 2 C 6 H 3 ) 2 SiH 2 (5c), respectively. The products were characterized by multinuclear NMR spectroscopy ( 1 H, 13 C, 19 F, 29 Si) and in case of 1a, 1b, 2a, 2b, 2c, 5c, and 6a also by X-ray crystallography.