Unusual Reactions of NacNacAl with Urea and Phosphine Oxides

The reaction of cyclic urea 1,3-dimethyl-2-imidazolidinone with the aluminum­(I) compound NacNacAl (1) gives an unexpected adduct of urea with the isomerized aluminum­(III) hydride NacNac′AlH­(OSIMe) (3). A related reaction of 1 with phosphine oxides results in cleavage of the PO bond and formation of hydroxyl derivatives NacNac′Al­(OH)­(OPR3) [R = Ph (5) and Et (6)]. Density functional theory calculations revealed that these reactions proceed via a bimolecular mechanism in which either the basic aluminum­(I) center or the transient AlO species deprotonate the methyl group of the NacNac ligand.