Reductive Dimerization of CO by a Na/Mg(I) Diamide.

Sodium reduction of [{SiNDipp}Mg] [{SiNDipp} = {CH2SiMe2N(Dipp)}2; Dipp = 2,6-i-Pr2C6H3] provides the Mg(I) species, [{SiNDipp}MgNa]2, in which the long Mg-Mg bond (>3.2 Å) is augmented by persistent Na-aryl interactions. Computational assessment indicates that this molecule is best considered to comprise a contiguous tetrametallic core, a viewpoint borne out by its reaction with CO, which results in ethynediolate formation mediated by the dissimilar metal centers.