Heterometallic alkoxides of molybdenum and heavy transition metals - the synthesis and prospects of application

The alkoxides of molybdenum and other heavy transition elements such as Ta or Nb were found to be unreactive towards each other. The bimetallic deriva tives could be obtained either via partial hydrolysis that gave Mo2Ta4O8(OM e)(16) (I) or via partial thermolysis that provided access to Mo4Ta2O8((OPr )-Pr-i)(1)4 (II), Mo3Ta2O8((OPr)-Pr-i)(10) (III), Mo4Ta4O16((OPr)-Pr-i)(12) (IV), Mo4Nb2O8((OPr)-Pr-i)(14) (V) and Mo4W2- xMo(x)O(10)((OPr)-Pr-i)(12) (VI). I-VI can be isolated only from hydrocarbon media as the presence of a lcohols leads to precipitation of insoluble homometallic derivatives of mol ybdenum. The cathodic reduction of MoO(OR)(4) (R = Me, Et) in the presence of LiCl and M(OR)(5) (M = Nb, Ta) leads only to formation of LiMo2O2(OMe)(7 )(MeOH) (VII) or LiMo2O2(OEt)(7) (VIII) respectively.