Coordination and Activation of N at Low-Valent Magnesium using a Heterobimetallic Approach: Synthesis and Reactivity of a Masked Dimagnesium Diradical.

The activation of dinitrogen (N ) by transition metals is central to the highly energy intensive, heterogeneous Haber-Bosch process. Considerable progress has been made towards more sustainable homogeneous activations of N with d- and f-block metals, though little success has been had with main group metals. Here we report that the reduction of a bulky magnesium(II) amide [( NON)Mg] ( NON=4,5-bis(2,4,6-tricyclohexylanilido)-2,7-diethyl-9,9-dimethyl-xanthene) with 5 % w/w K/KI yields the magnesium-N complex [{K( NON)Mg} (μ-N )]. DFT calculations and experimental data show that the dinitrogen unit in the complex has been reduced to the N dianion, via a transient anionic magnesium(I) radical. The compound readily reductively activates CO, H and C H , in reactions in which it acts as a masked dimagnesium(I) diradical.