Reactions of Dianionic α‑Diimine-Supported Dimagnesium(I) Compound [K(THF)3]2[LMg–MgL] with Nitriles

The Mg–Mg-bonded compound, [K­(THF)3]2[LMg–MgL] (1, L = [(2,6-iPr2C6H3)­NC­(Me)]22–), exhibits good reactivity toward a series of nitriles (RCN). Reaction of 1 with 2.0 equiv of Me3SiCN proceeded through reductive Si–C(CN) bond cleavage to generate the cyanide ions (CN–), which serve as bridges to link the tetrameric complex [L4Mg4(μ-CN)4K4(THF)6] (2). When more (3.0 equiv) of the nitrile substrates Me3SiCN or tBuCN were reacted with 1, both Si–C(CN) [or C–C(CN)] bond cleavage and terminal coordination of the nitriles occurred, leading to the tetramers [L4Mg4(μ-CN)4(RCN)2K4(THF)4] (R = Me3Si, 3 and R = tBu, 4). More interestingly, reaction of precursor 1 with 2.0 equiv of isobutyronitrile (iPrCN) or cyclohexyl nitrile (CyCN) that has α-hydrogen atoms afforded the dinuclear complexes [{K­(THF)2LMg­(μ-NCCMe2)}2] (6) and [{K­(Tol)­LMg­(μ-NCCC5H10)}2] (7) with bridging keteniminate ligands, representing a rare reductive deprotonation pathway for nitriles. All products were characterized by X-ray diffraction, NMR, and infrared spectra and density functional theory computations.