Titanium imido complexes with tetraaza macrocyclic ligands

Abstract

Tetraaza macrocycle-supported tert-butyl titanium imido complexes [Ti(NBu^t)(Me_ntaa)] (n = 4 2 or 8 3; H₂Me_ntaa = 6,8,15,17-tetra- or 2,3,6,8,11,12,17,18-octa-methyl-5,14-dihydrodibenzo[b,i][1,4,8,11]tetraazacyclotetradecine, respectively), [Ti(NBu^t)(Me₄taen)] (5, H₂Me₄taen = 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-4,6,11,13-tetraene) and [Ti(NBu^t)(TTP)] (6, H₂TTP = 5,10,15,20-tetratolylporphyrin) together with the N₂O₂-donor Schiff base analogue [Ti(NBu^t)(acen)] (7, H₂acen = 4,9-dimethyl-5,8-diazadodeca-3,9-diene-2,11-dione) were prepared in good yield from the readily available [Ti(NBu^t)Cl₂(py)₃] and the dilithium or disodium salts of the tetradentate ligands. The TiNBu^t groups in 2 and 3 underwent imido group exchange reactions with anilines to form [Ti(NR)(Me_ntaa)] (n = 4, R = C₆H₃Me₂-2,6 4, Ph, C₆H₄(NO₂)-4, C₆H₄(NMe₂)-4; n = 4 or 8, R = C₆H₄Me-4), and with H₂E (E = O or S) to give the oxo and sulfido analogues [Ti(E)(Me₄taa)]. Compound 4 was also prepared in good yield from [Ti(NC₆H₃Me₂-2,6)Cl₂(py)₃] and Li₂[Me₄taa]. Reaction of 2 with 2 or 1 equivalents of ROH (R = Me or C₆H₃Me₂-2,6) or pinacol afforded [Ti(OR)₂(Me₄taa)] and [Ti{OC(Me)₂C(Me)₂O}(Me₄taa)] respectively. The crystal structures of 3 and 4 have been described.