Titanium-Mediated Catalytic Hydrogenation of Monocyclic and Polycyclic Arenes

Two electron-reduction of the Ti(IV) guanidinate complex (Im^DippN)(^Xyketguan)TiCl₂ gives (η⁶-Im^DippN)(^xyketguan)Ti (1^intra) and (Im^DippN)(^Xyketguan)Ti(η⁶-C₆H₆) (1^inter) (^xyketguan = [(^tBuC=N)C(NXylyl)₂]^-, Xylyl = 2,5-dimethylphenyl) in the absence or presence of benzene, respectively. These complexes have been found to hydrogenate monocyclic and polycyclic arenes under relatively mild conditions (150 psi, 80 °C) – the first example of catalytic, homogeneous arene hydrogenation with TON > 1 by a Group IV system.