From alkaline earth to coinage metal carboranyls

Abstract

The β-diketiminato calcium and magnesium complexes, [(BDI)MgⁿBu] and [(BDI)CaH]₂ (BDI = HC{C(Me)NDipp}₂; Dipp = 2,6-di-isopropylphenyl), react with ortho-carborane (o-C₂B₁₀H₁₂) to provide the respective [(BDI)Ae(o-C₂B₁₀H₁₁)] (Ae = Mg or Ca) complexes. While the lighter group 2 species is a monomer with magnesium in a distorted trigonal planar environment, the heavier analogue displays a puckered geometry at calcium in the solid state due to Ca⋯H–B intermolecular interactions. These secondary contacts are, however, readily disrupted upon addition of THF to provide the 4-coordinate monomer, [(BDI)Ca(THF)(o-C₂B₁₀H₁₁)]. [(BDI)Mg(o-C₂B₁₀H₁₁)] was reacted with [NHC^IPrMCl] (NHC^IPr = 1,3-bis(isopropyl)imidazol-2-ylidene; M = Cu, Ag, Au) to provide [NHC^IPrM(o-C₂B₁₀H₁₁)], rare C-bonded examples of coinage metal derivatives of unsubstituted (o-C₂B₁₀H₁₁)⁻ and confirming the alkaline earth compounds as viable reagents for the transmetalation of the carboranyl anion.