The synthesis of W–O–W μ-oxo clusters by hydrolysis of tungsten aminoalkoxides and their structural characterisation

Abstract

The tungsten aminoalkoxides W(O)(OPrⁱ)₃L [L = dmae, OCH₂CH₂NMe₂ (1); bdmap, OCH(CH₂NMe₂)₂ (2); tdmap, OC(CH₂NMe₂)₃ (3)] have been synthesised. Controlled hydrolysis of 1–3 has allowed isolation of W₄O₄(μ-O)₆(dmae)₄ (4), W₄O₄(μ-O)₄(OPrⁱ)₄(bdmap)₄ (5), W₆O₆(μ-O)₉(tdmap)₆ (6), W₄O₄(μ-O)₆(tdmap)₄ (7), W₄O₄(μ-O)₆(tdmap)₄·4H₂O (7a), all of which have been characterised by X-ray crystallography. 4, 7, 7a each embody a W₄O₆ core with adamantane structure, 5 incorporates a folded W₄O₄ square and 6 has a trigonal prismatic W₆O₉ at its heart. 7 decomposes in air at to give orthorhombic WO₃, while 1–3 decomposed under an autogenerated pressure (Reaction under Autogenic Pressure at Elevated Temperatures, RAPET) to form mixtures of carbon-coated WO_x needles and carbon spherules.