The Role of Ancillary Ligands on the Reactivity of Monocyclopentadienyl Tantalum Complexes with Water

The reaction of [TaCp*Me3(OTf)] with chelidamic acid yields the carboxylate derivative [TaCp*Me(OTf)((OOC)2py(OH)-κ3-O,N,O)] (1) that reacts with water to yield the cationic dimetallic complex [{TaCp*((OOC)2py(OH)-κ3-O,N,O)}2(μ2-OH)3](OTf) (2). In an analogous procedure, the reaction of [TaCp*Me3(OTf)] with diglycolic acid renders the triflate compound [TaCp*Me{(OOCCH2)2O}-κ3-O,O,O)(OTf)] (4). Citric acid (CITH4) reacts with [TaCp*Me4] and water to give the dimetallic complex [{TaCp*(CITH)(OH2)}(μ-O){TaCp*(CITH2)(OH)}] (6). Compound [TaCp*Me3(OTf)] reacts with an excess of water in CH2Cl2 to give the trimetallic tantalum hydroxide [{TaCp*(OH)(OH2)}3(μ3-OH)(μ2-O)3](OTf)2 (7). Complexes 2, 6 and 7 have been studied by X-ray diffraction.