Tin hydrides have been widely employed in stoichiometric and catalytic hydrogen atom transfer to a diverse range of substrates. Industrially relevant tin hydrides predominately feature tin in the +4 oxidation state. However, recent advances in group 14 hydride chemistry have introduced a range of tin hydride species formally in the +2 oxidation state that enable new reactivity profiles and pathways. Herein, we describe the synthesis, structure, and spectroscopy of a divalent tin hydride capped trinuclear nickel cluster, [Ni3(dppm)3(μ3-H)(μ3-SnH)], 2, with a surprising range of redox chemistry, including two reversible oxidations and one partially-reversible reduction. Complex 2 exhibits a monomeric divalent tin hydride bound to a transition metal and a rare example of a formally 44-electron trinuclear nickel cluster that features significant, and reversible redox chemistry. Treatment of the trichlorotin-capped trinuclear nickel cluster, [Ni3(dppm)3(μ3-Cl)(μ3-SnCl3)], 1, with 4 eq. NaHB(Et)3 yields a μ3-SnH capped trinuclear nickel cluster, [Ni3(dppm)3(μ3-H)(μ3-SnH)], 2. Electrochemical studies of 2 reveal that the cluster undergoes two reversible one-electron oxidation events (E = -1.3 V, -0.8 V vs. Fc0/+) and one partially-reversible one-electron reduction (E = -2.7 V vs. Fc0/+) event. The solid-state structure, determined by single-crystal X-ray diffraction, nuclear magnetic resonance (NMR) spectroscopy, and computational studies support that 2 is a divalent tin hydride. Preliminary reactivity studies of 2 are ongoing and indicate high levels of reactivity with H2 and D2.

Unusual case of a µ3-SnH capped trinuclear nickel cluster with a Sn: lone pair that activates H2

ACS Spring 2022

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