Synthesis, isolation and structural characterisation of alkoxytitanium triflate complexes

Treatment of [Ti(OiPr)4] with trimethylsilyl triflate results in the formation of [Ti(OiPr)3(OTf)] (2) in high yield. Subsequent treatment of the triflate derivative 2 with a series of facially coordinating N3-donor ligands results in the production of a series of charge-separated metal alkoxide salts of the general formula [{L}Ti(OiPr) 3][OTf] {L = tris(pyrazolyl)methane (3a), 1,3,5-triethyl-1,3,5- triazacyclohexane (3b), 1,3,5-tribenzyl-1,3,5-triazacyclohexane (3c), 1,3,5-tris(p-fluorobenzyl)-1,3,5-triazacyclohexane (3d), and 1,3,5-tris[(1S)-1-phenylethyl]-1,3,5-triazacyclohexane (3e)}. The products were characterized by 1H and 13C NMR spectroscopy and in the case of 3a-c by single-crystal X-ray diffraction. Reaction of 2 with 1,3,5-triphenyl-1,3,5-triazacyclohexane results in the formation of complex 4 [{L′}2Ti(OiPr)2(OTf)2], which contains two 3,4-dihydroquinazoline ligands (L′), a result of catalytic activation of the triazacyclohexane ligands by [Ti(OiPr)3(OTf)] towards electrophilic aromatic substitution.