Photochemistry of tris(pyrazolyl)borate titanium(IV) complexes

Complexes LTiCl3 (1,2) (1: L = Tp = hydrotris(pyrazol-1-yl)borate, 2: L = Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) show LMCT absorption at λ = 315 nm and at λ = 328 nm, respectively. Photolysis of 1 and 2 in THF generated radical species L and TiCl3(THF) in the primary photochemical processes. Photolysis of LTiCl2(TEMPO) (5,6) (5: L = Tp, 6: L = Tp*, TEMPO = 2,2,6,6-tetramethyl-1-piperidinyloxy) generate Ti(III) and the TEMPO radical in the primary photochemical event. The primary photoproducts have been studied by ESR and electronic spectroscopy.