Abstract
<jats:p>Experimental measurements of hydricity (ΔGH–) quantify the equilibrium between a metal hydride (H–M) and its hydride-deficient congener (M+). However, periodic trends for transferring H– have proven less predictable than those for H• and H+ amongst 3d/4d/5d congeners. Building off existing work, we characterize the series [H–MII(EtXantphos)2]+ and [MII(EtXantphos)2]2+ (M = Ni, Pd, Pt; EtXantphos = 9,9-dimethyl-9H-xanthene-4,5-diyl)-bis(diethylphosphane). Relatively similar structures are observed amongst [MII(EtXantphos)2]2+. However, both pseudo-tetrahedral and trigonal bipyramidal structures are observed for [H–MII(EtXantphos)2]+. The structural rearrangement that occurs on Pd and Pt (but not Ni) contributes up to 8.0 kcal mol-1 in free energy. So, the free energy for structural reorganization can meaningfully affect ΔGH–; these factors may be entangled with existing investigations into periodic trends.</jats:p>