Magnesium-magnesium Bond Stabilized By A Doubly Reduced A-diimine:synthesis And Structure Of [k(thf)_3]_2[lmg-mgl] (l = [(2,6-~ipr_2c_6h_3)nc(me)]_2~(2-))

摘要

Metal-metal bonding as an important dimension of chemistry has attracted much attention in the past decades. Besides the concept of multiple bonds between transition metals developed by Cotton, a number of metal-metal bonds involving both p- and d-block metals have been reported in recent years, such as the silicon-silicon triple bond and the chromium-chromium quintuple bond. In 2004, the first stable compound containing a Zn-Zn bond, Cp*Zn-ZnCp*, was synthesized by Carmona and co-workers. Consequently, computations were carried out by different research groups not only on the Zn-Zn bond but also on the relevant, then-unknown Mg-Mg bond, leading to the prediction that the latter could also exist. In 2007, Green, Jones, and Stasch confirmed this hypothesis by the isolation of two Mg-Mg-bonded compounds, RMgMgR (1, R~1 = [(Ar)NC(N~iPr_2)N(Ar)]~-; 2, R~2 = {[(Ar)NC(Me)]_2-CH}~-; Ar = 2,6-diisopropylphenyl), the first structurally characterized stable molecules with group 2 metal-metal bonds. Very recently, the same group reported a series of Lewis base (THF, dioxane, and pyridines) adducts of 2 (2a-d) with longer Mg-Mg bonds as well as two magnesium(II) hydrides, [MgR~2(μ-H)]_2 and [MgR~2(THF)(μ-H)]_2.