SYNTHETIC APPROACHES TO LOW OXIDATION STATE GALLIUM COMPOUNDS

The possibility of preparing compounds of gallium(I) which incorporate (trimethylsilyl)methyl, cyclopentadienyl or pentamethyl- cyclopentadienyl ligands has been investigated. Previous publications reporting the preparations of gallium(I) and indium(I) compounds via reductive elimination of SiMe(,4) from reactions of alkali-metal hydrides with Ga(CH(,2)SiMe(,3))(,3) and In(CH(,2)SiMe(,3))(,3) have been proven incorrect. Reactions of alkali-metal hydrides with Ga(CH(,2)SiMe(,3))(,3) and In(CH(,2)SiMe(,3))(,3) have led to the isolation and characterization of the following (trimethylsilyl)methyl derivatives of gallium(III) and indium(III): KGa(CH(,2)SiMe(,3))(,3)H, LiGa(CH(,2)SiMe(,3))(,3)H(.)(1,2-dimethoxyethane), {lcub}Ga(CH(,2)SiMe(,3))(,3){rcub}(,2)(.); (N,N,N',N'-tetramethylethylenediamine), KGa(CH(,2)SiMe(,3))(,2)H(,2), KIn(CH(,2)SiMe(,3))(,3)H, KIn(CH(,2)SiMe(,3))(,4), NaIn(CH(,2)SiMe(,3))(,3)H, and NaIn(CH(,2)SiMe(,3))(,4). An attempted preparation of the neutral alkylgallium(III) hydride, Ga(CH(,2)SiMe(,3))(,2)H, is described. The cyclopentadienylgallium(III) compounds Ga(C(,5)H(,5))(,3), Ga(C(,5)H(,5))(,2)Cl, Ga(C(,5)H(,5))Cl(,2) and NaGa(C(,5)H(,5))(,4) have been prepared and fully characterized. The pentamethylcyclopentadienylgallium(III) compounds Ga(C(,5)Me(,5))(,3), Ga(C(,5)Me(,5))(,2)Cl and Ga(C(,5)Me(,5))Cl(,2) have also been prepared and fully characterized. Reactions of sodium naphthalenide with these cyclopentadienyl and; pentamethylcyclopentadienylgallium(III) compounds have been explored as possible routes to the formation of low oxidation state gallium compounds. Reactions of the mixed valent compounds Ga('+)GaX(,4)('-) with Li(C(,5)H(,5)) and Na(C(,5)H(,5)) have also been examined as possible routes to the formation of low oxidation state gallium compounds. In almost every case, attempts to prepare low oxidation state gallium compounds have led instead to the formation of gallium metal and organogallium(III) species. The reaction of sodium naphthalenide with Ga(C(,5)H(,5))Cl(,2) was unique among the reactions studied in that gallium metal was not formed and all data are consistent with the formation of a species of the composition Ga(C(,5)H(,5))(.)xTHF (x (LESSTHEQ) 1), which may contain gallium in the +1 oxidation state. X-ray crystal structures are reported for the following compounds: KGa(CH(,2)SiMe(,3))(,3)H, {lcub}Ga(CH(,2)SiMe(,3))(,3){rcub}(,2)(.)(N,N,N',N'-tetramethylethylenediamine), Ga(C(,5)H(,5))(,3), Ga(C(,5)Me(,5))(,2)Cl, Ga(C(,5)Me(,5))Cl(,2) and KIn(CH(,2)SiMe(,3))(,4).