Reactions of gallium(III) chloride with Li[E(SiMe3)3](E = Si or Ge): crystal structure of (R3Ge)ClGa(µ-OEt)2GaCl(GeR3)(R = SiMe3)
Abstract
Reactions of Li(ER3)(thf)x(E = Si or Ge, R = SiMe3, thf = tetrahydrofuran) with gallium(III) chloride were carried out in diethyl ether with 1 : 1 and 2 : 1 stoichiometries. The 1 : 1 reactions gave products that decomposed upon recrystallization from pentane or drying in vacuo. The NMR spectra were consistent with a mixture of Li[R3SiGaCl3](thf)4(major) and GaCl2(SiR3)·thf (minor) in the case of E = Si and GaCl2(GeR3)·thf for E = Ge. The 2 : 1 E = Ge reactions gave a mixture of two products exhibiting needle and plate crystal morphologies. The NMR spectra and a partial structure determination identified the former as Li[R3GeGaCl3](thf)4. A full structure determination of the latter showed it to be the diethoxy-bridged dimer, (R3Ge)ClGa(µ-OEt)2GaCl(GeR3). The latter product is thought to result from cleavage of the ether solvent by either Ga2Cl6 or the intermediate gallium complex. Possible pathways are discussed.