Hetero-alkoxide group (IV) and (V) neo-pentoxide compounds. Syntheses, characterizations, and X-ray structures of [Zr(mu-OCHMe2)(OCH2CMe3)(3)(HOCH2CMe3)](2) and [Ta(mu-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(mu-OPri) (ONp)(3)(HONp)](2) (1) and [Ta(mu-OEt)(ONp)(4)](2) (2), respectively. Compo unds 1 and 2 were found to adopt an edge-shared bioctahedral geometry, [M(m u-OR')(OR)(5)](2), with the smaller ligands acting as the bridge between th e two metal centers. For 1, the octahedral geometry around the metal center is completed by the coordination of a HONp solvent molecule. The solid sta te structure of 1 was retained in saturated solutions but at lower concentr ations, dynamic behavior associated with a mononuclear-dinuclear equilibriu m was observed. For 2, at low concentrations an equilibrium between mononuc lear and dinuclear complexes was noted; however, at higher concentrations a dinuclear-higher-nuclearity equilibrium was noted.