Synthesis, structure and theoretical studies of the hydrido inverse crown [K2Mg2(NiPr2)(4)(mu-H)(2)center dot(toluene)(2)]: a rare example of a molecular magnesium hydride with a Mg-(mu-H)(2)-Mg double bridge

Reaction of benzylpotassium, n,s-dibutylmagnesium and diisopropylamine in boiling toluene produces a rare example of a molecular magnesium hydride with a Mg-(mu-H)(2)-Mg double bridge, in [K2Mg2(NiPr2)(4)(mu-H)(2).(toluene)(2)] (1). In an effort to rationalise the formation of 1, a series of DFT calculations were performed. This report of 1 establishes the first isostructural pair of Na and K complexes solvated by toluene to be reported in the Cambridge Crystallographic Database. In comparison with its previously reported Na analogue, 2, the metal-arene centroid distances are considerably shorter (by 0.159 Angstrom) in the new complex reported here. It was found that a hydrocarbon solution of 1 is capable of reducing benzophenone to benzhydrol in moderate yields (74%).