Tethered Bis-Amidinates as Supporting Ligands: A Concerted Elimination/σ–π Rearrangement Reaction Forming an Unusual Titanium Arene Complex

A 1,4-cyclohexadiene dianion resonance structure makes a significant contribution to the structure of the (arene)Ti complex [LTi(η⁶-PhCH₃)] (see picture on the right). Labeling experiments have demonstrated that the structure forms through an unusual elimination/σ–π rearrangement reaction in which [LTi(CH₂Ph)₂] reacts readily with hydrogen; the use of the cyclohexane-linked bis-amidinate ligand L with constrained geometry makes the transformation possible.