[Ti(py)₄I₂] as an Entry Point to Titanium(II) Chemistry via Titanium Metal Oxidation

Access to defined titanium(II) compounds is crucial for their use in synthesis and catalysis. Most established routes to Ti(II) compounds rely on the reduction of Ti(III) or Ti(IV), an approach that intrinsically limits atom efficiency and can introduce byproducts or lead to mixed-valency complexes. Here, an alternative strategy for obtaining Ti(II) is presented, based on the oxidation of Ti metal by iodine. Ti diiodide formed in this reaction is subsequently complexed to afford the novel Ti(II) complex [Ti(py)₄I₂] on a gram scale (> 30 g, 50 mmol) in a highly atom-efficient approach. Revision of the original synthesis of TiI₂ shows that excess Ti metal is required to prevent the formation of higher Ti iodides, enabling clean access to Ti(II) without reductive agents. The resulting Ti(II) complex serves as a synthetic entry point for Ti(II) chemistry, as illustrated by a ligand exchange reaction to form [Ti(2,2'-bipyridine)₂I₂].