Diterphenylgallium Alkyls and Hydride:  Synthesis, Characterization, and Reactivity

Abstract

The reactions of (2,6-Mes 2 C 6 H 3 ) 2 GaCl ( 2 ) with LiMe, Li- t -Bu, and LiHBEt 3 afforded the bis(terphenyl)gallium compounds (2,6-Mes 2 C 6 H 3 ) 2 GaMe ( 3 ), (2,6-Mes 2 C 6 H 3 ) 2 Ga- t -Bu ( 4 ) and (2,6-Mes 2 C 6 H 3 ) 2 GaH ( 5 ). Hydrolysis of 2 and 3 gave the dimeric, hydroxide-bridged species [2,6-Mes 2 C 6 H 3 Ga(Cl)(μ-OH)] 2 ( 6 ) and [2,6-Mes 2 C 6 H 3 Ga(Me)(μ-OH)] 2 ( 7 ) via loss of the terphenyl substituent as 1,3-Mes 2 C 6 H 4 . Hydrolysis of 5 led to the loss of H 2 and the formation of the monomeric (2,6-Mes 2 C 6 H 3 ) 2 GaOH ( 8 ). The compounds were characterized by FTIR and 1 H and 13 C{ 1 H} NMR spectroscopy and X-ray crystallography. The structural studies of the diterphenyl compounds 2 − 5 and 8 showed the highly flexible nature of these compounds, as expressed in the wide range of the C Terph −Ga−C Terph angles from 113.23° in 4 to 153.5° in 2 . Methyl and hydride abstraction from 3 and 5 with the Lewis acids [Ph 3 C] + [B(C 6 F 5 ) 4 ] - and B(C 6 F 5 ) 3 afforded the ionic species [(2,6-Mes 2 C 6 H 3 ) 2 Ga] + [B(C 6 F 5 ) 4 ] -, [(2,6-Mes 2 C 6 H 3 ) 2 Ga] + [MeB(C 6 F 5 ) 3 ] -, and [(2,6-Mes 2 C 6 H 3 ) 2 Ga] + [HB(C 6 F 5 ) 3 ] -, all of which contain the linear two-coordinate cation [(2,6-Mes 2 C 6 H 3 ) 2 Ga] + ( 1 + ).