Two‐Coordinate Magnesium(I) Dimers Stabilized by Super Bulky Amido Ligands

A variety of very bulky amido magnesium iodide complexes, LMgI(solvent) 0/1 and [LMg(μ‐I)(solvent) 0/1 ] 2 (L=‐N(Ar)(SiR 3 ); Ar=C 6 H 2 {C(H)Ph 2 } 2 R′‐2,6,4; R=Me, Pr i , Ph, or OBu t ; R′=Pr i or Me) have been prepared by three synthetic routes. Structurally characterized examples of these materials include the first unsolvated amido magnesium halide complexes, such as [LMg(μ‐I)] 2 (R=Me, R′=Pr i ). Reductions of several such complexes with KC 8 in the absence of coordinating solvents have afforded the first two‐coordinate magnesium(I) dimers, LMg−MgL (R=Me, Pr i or Ph; R′=Pr i , or Me), in low to good yields. Reductions of two of the precursor complexes in the presence of THF have given the related THF adduct complexes, L(THF)Mg−Mg(THF)L (R=Me; R′=Pr i ) and LMg−Mg(THF)L (R=Pr i ; R′=Me) in trace yields. The X‐ray crystal structures of all magnesium(I) complexes were obtained. DFT calculations on the unsolvated examples reveal their Mg−Mg bonds to be covalent and of high s‐character, while Ph⋅⋅⋅Mg bonding interactions in the compounds were found to be weak at best.