Diterphenylgallium Alkyls and Hydride: Synthesis, Characterization, and Reactivity

The reactions of (2,6-Mes2C6H3)2GaCl (2) with LiMe, Li-t-Bu, and LiHBEt3 afforded the
bis(terphenyl)gallium compounds (2,6-Mes2C6H3)2GaMe (3), (2,6-Mes2C6H3)2Ga-t-Bu (4) and
(2,6-Mes2C6H3)2GaH (5). Hydrolysis of 2 and 3 gave the dimeric, hydroxide-bridged species
[2,6-Mes2C6H3Ga(Cl)(μ-OH)]2 (6) and [2,6-Mes2C6H3Ga(Me)(μ-OH)]2 (7) via loss of the
terphenyl substituent as 1,3-Mes2C6H4. Hydrolysis of 5 led to the loss of H2 and the formation
of the monomeric (2,6-Mes2C6H3)2GaOH (8). The compounds were characterized by FTIR
and 1H and 13C{1H} 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 CTerph−Ga−CTerph angles from 113.23° in 4 to 153.5°
in 2. Methyl and hydride abstraction from 3 and 5 with the Lewis acids [Ph3C]+[B(C6F5)4]-
and B(C6F5)3 afforded the ionic species [(2,6-Mes2C6H3)2Ga]+[B(C6F5)4]-, [(2,6-Mes2C6H3)2Ga]+[MeB(C6F5)3]-, and [(2,6-Mes2C6H3)2Ga]+[HB(C6F5)3]-, all of which contain the linear
two-coordinate cation [(2,6-Mes2C6H3)2Ga]+ (1+).