Matt de Vere (@mattdv-t.bsky.social)

So great to finally see this out! I remember looking at the very first NMRs of the hydride-hydroxide feeling utterly baffled how the MgH resonance only integrated to 1 relative to the two ligands! Great work from Stuart and Samuel on the synth and Rochelle on the calcs! pubs.acs.org/doi/10.1021/...

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Facile, Reversible Hydrogen Activation by Low-Coordinate Magnesium Oxide Complexes New approaches to achieve facile and reversible dihydrogen activation are of importance for synthesis, catalysis, and hydrogen storage. Here we show that low-coordinate magnesium oxide complexes [{(RDipnacnac)Mg}2(μ-O)] 1, with RDipnacnac = HC(RCNDip)2, Dip = 2,6-iPr2C6H3, R = Me (1a), Et (1b), iPr (1c), readily react with dihydrogen under mild conditions to afford mixed hydride-hydroxide complexes [{(RDipnacnac)Mg}2(μ-H)(μ-OH)] 4. Dehydrogenation of complexes 4 is strongly dependent on remote ligand substitution and can be achieved by simple vacuum-degassing of 4c (R = iPr) to regain 1c. Donor addition to complexes 4 also releases hydrogen and affords donor adducts of magnesium oxide complexes. Computational studies suggest that the hydrogen activation mechanism involves nucleophilic attack of an oxide lone pair at a weakly bound H2···Mg complex in an SN2-like manner that induces a heterolytic dihydrogen cleavage to yield an MgOH and an MgH unit. Alternative synthetic routes into complex 4b from a magnesium hydride complex have been investigated and the ability of complexes 1 or 4 to act as catalysts for the hydrogenation of 1,1-diphenylethene (DPE) has been tested. https://pubs.acs.org/doi/10.1021/jacs.4c16041