Heterotri- and -tetrametallic alkoxides of chromium(III) containing aluminium(III), gallium(III) and niobium(V)

CrCl3 · 3THF reacts with two equivalents of potassium alkoxometallates K{M(OPri)x} [M = Al(A), Ga(B), x = 4; M = Nb(C), x = 6] to give heterobimetallic chloride isopropoxides [Cr{M(OPri)x}2Cl(THF)] [M = Al(A − 1), Ga(B − 1), and Nb(C − 1)], in which the replacement of the chloride with an appropriate alkoxometallate (tetraisopropoxoaluminate, tetraisopropoxogallate, or hexaisopropoxoniobate) results in the formation of novel heterotrimetallic derivatives. The ‘single pot’ synthesis of an heterotetrametallic isopropoxide [Cr{Nb(OPri)6}{Al(OPri)4}{Ga(OPri)4}] (7) has been carried out by the sequential addition of (A), (B), and (C) to a benzene suspension of CrCl3 · 3THF. Alcoholysis of [Cr{Al(OPri)4}2{Nb(OPri)6}] (1) and [Cr{Al(OPri)4}2{Ga(OPri)4}] (5) with t-BuOH has also been studied and the derivatives characterized by elemental analyses, molecular weight determinations, spectroscopic [Electronic, i.r., 27Al-n.m.r.] and magnetic susceptibility studies.