Alkylation, cation formation, and insertion reactions in titanium tris(ketimide) complexes

Ti((NCBu2)-Bu-t)(3)Cl (1) reacts with TlPF6 in acetonitrile to afford [Ti((NCBu2)-Bu-t)(3)(NCCH3)]PF6 (2), which proved to be unstable and decomposed at room temperature either in solution or in the solid state. Attempts to recrystallize 2 from a CH2Cl2/hexane mixture led to [Ti-3((NCBu2)-Bu-t)(6)(mu(2)-F)(3)(mu(3)-F)(2)][PF6] (3). Treatment of 1 with LiMe and PhCH2MgCl gave the compounds Ti((NCBu2)-Bu-t)(3)CH2Ph (4) and Ti((NCBu2)-Bu-t)(3)Me (5), respectively. 4 was treated with B(C6F5)(3) to afford [Ti((NCBu2)-Bu-t)(3)(CH2Ph)B(C6F5)(3)] (6), which exists in solution as a mixture of two species, the zwitterion [Ti((NCBu2)-Bu-t)(3)][(mu-CH2Ph)B(C6F5)(3)] (6A) and the solvate cation [Ti((NCBu2)-Bu-t)(3)(Solv)][(CH2Ph)B(C6F5)(3)] (6B). Above 60 degrees C, C6F5 is transferred to the metal center and Ti((NCBu2)-Bu-t)(3)(C6F5) (9) forms. This compound participates in a dynamic process in solution involving Ti center dot center dot center dot F interactions. The fluxional process observed for 6 can be stopped upon addition of 1 equiv of CNMes, giving [Ti((NCBu2)-Bu-t)(3)(CNMes)][(CH2Ph)B(C6F5)(3)] (7). CNMes does not insert into Ti-N bonds, but it readily inserts into the Ti-C bond of Ti((NCBu2)-Bu-t)(3)(Me) (5) to afford [Ti((NCBu2)-Bu-t)(3){eta(2)-C(CH3)NMes}] (8).