Group IV metal σ-alane complexes derived from an anionic cyclic (alkyl)(amino)aluminum dihydride.

An anionic cyclic (alkyl)(amino)aluminum dihydride was synthesized using a metathesis reaction between the corresponding aluminum iodide precursor and lithium aluminum hydride. The reaction with Cp2TiCl2 affords a paramagnetic σ-alane Ti complex bearing the Al-(μ-H)2-Ti core, whereas the employment of Cp2MCl2 (M = Zr, Hf) yields diamagnetic σ-alane complexes. A joint experimental and computational study reveals that Ti is reduced to the +III oxidation state during the reaction, while Zr and Hf retain the +IV oxidation state.