Experimental and Theoretical Studies on the Reactivity of Titanium Chelidamate Complexes: the Significant Role of the Hydroxide Pyridine Moiety

The reaction of [TiCp2Cl2] with dipotassium chelidamate yields the carboxylate derivative [TiCp2{(OOC)2PyOH}] (2), which is sparsely soluble in water at neutral pH but soluble in basic medium. [TiCp*Cl3] reacts with chelidamic acid in the presence of NEt3 to yield the dimetallic derivative [TiCp*{(OOC)2PyOH}]2O (5). The reaction of [TiCp*Cl3] with potassium chelidamate renders the hydroxide compound [TiCp*(OH){(OOC)2PyOH}] (6). Compound 6 evolves in DMSO solution to give the trimetallic derivative [TiCp*(DMSO){(OOC)2PyO}]3 (7). Complex 6 reacts with NaOH to render the heterometallic complex [TiCp*{(OOC)2PyONa(OH2)3}]2(O) (8). The structures of complexes 7 and 8b were determined by X-ray diffraction studies. The electrostatic potential surfaces, Mulliken population analysis, and frontier molecular orbitals were determined for complex 6, allowing us to infer its reactivity.