A Unique Chlorine–Methyl Exchange Reaction upon Treatment of Dichloroorganogallium Compounds, RGaCl₂, with the Bulky Alkyllithium Derivative LiC(SiMe₃)₃

Abstract

Reaction of the organogallium chlorides C 6 H 6– n [C(H)═C(GaCl 2 )-SiR 3 ] n ( 1 to 4; R = Me, Ph) with the bulky alkyllithium derivative Li(THF) 2 C(SiMe 3 ) 3 did not afford the expected alkylgallium chlorides by salt elimination. Instead, compounds ( 5 to 7 ) were isolated that had methyl groups attached to gallium, while chlorine atoms moved to silicon to yield Ga(Me)-C(SiMe 3 ) 2 (SiMe 2 Cl) moieties. On the basis of quantum chemical calculations the formation of these unprecedented structural motifs is caused by kinetic control involving cyclic transition states as initiating steps. The anticipated, but experimentally not observed products having the intact Ga(Cl)-C(SiMe 3 ) 3 subunits ( 8 ) were calculated to be thermodynamically favored.