Alkaline earth metal-assisted dinitrogen activation at nickel.

Rare examples of trinuclear [Ni-N 2 -M-N 2 -Ni] core (M = Ca, Mg) with linear bridged dinitrogen ligands are reported in this work. The reduction of [ i Pr 2 NN]Ni(μ-Br) 2 Li(thf) 2 (1) ( i Pr 2 NN = 2,4-bis-(2,6-diisopropylphenylimido)pentyl) with elemental Mg or Ca in THF under an atmosphere of dinitrogen yields the complex { i Pr 2 NNNi(μ-N 2 )} 2 M (thf) 4 (M = Mg, complex 2 and M = Ca, complex 3). The bridging end-on (μ-N 2 ) 2 M(thf) 4 moiety connects the two [ i Pr 2 NNNi] - nickelate fragments. A combination of X-ray crystallography, solution and solid-state spectroscopy have been applied to characterize complexes 2 and 3, and DFT studies have been used to help explain the bonding and electronic structure in these unique Ni-N 2 -Mg and Ni-N 2 -Ca complexes.