Oxo and Hydroxo Organometallic Complexes of Tantalum: Soluble Molecular Models of Tantalum Oxide

The tantalum complex [TaCp*Cl₂{2,6(OOC)₂py-κ²O,O}] (1) has been synthesized by reaction of [TaCp*Cl₄], Cp* = η⁵-C₅Me₅, with 2,6-pyridinedicarboxylic acid. Complex 1 reacts with AgOTf, OTf = trifluoromethylsulfate, to yield the new tantalum carboxylate derivative [TaCp*Cl(OTf){2,6(OOC)₂py-κ²O,O}] (2) or with KOH to render the dinuclear oxo compound [TaCp*(μ-O){2,6(OOC)₂py-κ²O,O}] ₂ (3). The reaction of 3 with H₂O and HOTf gives the dinuclear hydroxo derivative [{TaCp*{2,6(OOC)₂py-κ²O,O}}₂(μ-OH)₃](OTf) (5). The structures of complexes 1, 2, 3, and 5 have been established by X-ray diffraction methods.