Titanium imido complexes of pendant arm functionalised benzamidinate ligands

Reactions of the lithiated pendant arm functionalised benzamidinates Li{Me2NCH2CH2NC(Ph)NSiMe3} and Li{Me2NCH2CH2CH2NC(Ph)NSiMe3} with the compounds [Ti(NR)Cl-2(py)(3)] (R = Bu-t, 2,6-Me2C6H3, 2,6- (Pr2C6H3)-Pr-i) afforded five-coordinate [Ti(NR){Me2NCH2CH2NC(Ph)NSiMe3}Cl] 1-3 and [Ti(NR){Me2NCH2CH2CH2NC-(Ph)NSiMe3}Cl] 4-6, respectively. Reaction of [Ti((NBu)-Bu-t){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] 4 with C6F5NH2 gave elimination of (BuNH2)-Bu-t and the corresponding perfluoroarylimido complex 7. The X-ray crystal structures of [Ti((NBu)-Bu-t){Me2NCH2CH2NC(Ph)NSiMe3}Cl] 1 and [Ti(N-2,6-R2C6H3){Me2NCH2CH2CH2NC(Ph)NSiMe3}Cl] (R = Me 5 or Pr-i 6) have been determined. Reaction of either 1 or 4 with H2N-2,6-Me2C6H3 in C6D6 afforded the corresponding arylimido compounds 2 and 5, but this route is not amenable to easy scale-up. For better evaluation of the effects of the pendant NMe2 donor group in 1-6, the bis(pyridine) compound [Ti((NBu)-Bu-t){MeCH2CH2NC-(Ph)NSiMe3}Cl(py)(2)] 9 was prepared from Li{MeCH2CH2NC(Ph)NSiMe3} 8 and [Ti((NBu)-Bu-t)Cl-2(py)(3)]. The compounds 1-3 with two-carbon pendant arms are quite sensitive to adventitious protonation, and the X-ray crystal structures of the products of two such reactions, namely [Ti-2{Me2NCH2CH2N=C(Ph)N(H)SiMe3}(2)((NBu)-Bu-t)(2)Cl-2(mu-Cl)(2)] 10 and [Ti-2(N-2,6-C6H3Me2)(2)Cl-2(mu-O){Me2NCH2CH2N=C(Ph)N(H)SiMe3}(2)] 11, have been determined. Both possess amidine ligands that show interesting intramolecular N-H ... X (X = mu-Cl or mu-O) hydrogen bonds.