Lithium bridged cyclosiloxy-niobium(V) and -tantalum(V) complexes: thermal decomposition, solid-state and solution structural studies †

Abstract

Treatment of MCl₅ (M = Nb or Ta) with 3 equivalents of dilithium tetraphenyldisiloxanediolate, [(Ph₂SiOLi)₂O], gave the lithium-bridged metallasiloxane complex, [M{O(SiPh₂O)₂}₃]-µ-[Li(L) ₂] (M = Nb 1 or M = Ta 2; L = pyridine). The solid-state structure of compound 2 determined by single crystal X-ray diffraction is reported. Variable-temperature ⁷Li NMR of 2 revealed two separate exchange processes which may account for the equilibration of non-equivalent silicon environments in 1 and 2. Preparative scale thermal decomposition of the solid samples with L = tetrahydrofuran (thf ) gave crystalline LiNbO₃ and LiTaO₃.

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