HETERO-ALKOXIDE GROUP (IV) AND (V) NEO-PENTOXIDE COMPOUNDS. SYNTHESES, CHARACTERIZATIONS, AND X-RAY STRUCTURES OF [Zr(μ-OCHMe2)(OCH2CMe3)3(HOCH2CMe3)]2 AND [Ta(μ-OCH2Me)(OCH2CMe3)4]2

The alcoholysis exchange between excess HONp and [Zr(OPri)4(HOPri)]2 or “Ta(OEt)5” led to isolation of the mixed-alkoxide compounds [Zr(μ-OPri)(ONp)3(HONp)]2 (1) and [Ta(μ-OEt)(ONp)4]2 (2), respectively. Compounds 1 and 2 were found to adopt an edge-shared bioctahedral geometry, [M(μ-OR')(OR)5]2, with the smaller ligands acting as the bridge between the two metal centers. For 1, the octahedral geometry around the metal center is completed by the coordination of a HONp solvent molecule. The solid state structure of 1 was retained in saturated solutions but at lower concentrations, dynamic behavior associated with a mononuclear-dinuclear equilibrium was observed. For 2, at low concentrations an equilibrium between mononuclear and dinuclear complexes was noted; however, at higher concentrations a dinuclear-higher-nuclearity equilibrium was noted.