Deoxygenating Reduction of CO 2 by [Cp*Al] 4 to Form a (Al 3 O 2 C) 2 Cluster Featuring Two Ketene Moieties.

Herein we report that the reaction of the low-valent aluminum(I) species [Cp*Al] 4 (Cp* = pentamethylcyclopentadienyl) with CO 2 exhibits complete cleavages of the C═O bonds. The deoxygenating reduction reaction of [Cp*Al] 4 with CO 2 at 120 °C afforded [(Cp*) 3 Al 3 O 2 C(CO)] 2 ( 1 ), which featured two stacked (Al 3 O 2 C) 2 units and two C═C═O ketene moieties. Moreover, the isoelectronic analogues of diimine and isothiocyanate with CO 2 were also investigated, and the reactions of [Cp*Al] 4 with Dipp*-N═C═N-Dipp* and Dipp-C═N═S [Dipp* = 2,6-bis(diphenylmethyl)-4- tert -butylphenyl; Dipp = 2,6-diisopropylphenyl] afforded dialuminylimine ( 2 ) and tetrameric [Cp*AlS] 4 ( 3 ), respectively.