Synthesis, structure and reactivity of μ3-SnH capped trinuclear nickel cluster

Abstract

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 [dppm = bis(diphenylphosphino)methane]. Single-crystal X-ray diffraction, nuclear magnetic resonance (NMR) spectroscopy, and computational studies together support that cluster 2 is a divalent tin hydride. Complex 2 displays a wide range of reactivity including oxidative addition of bromoethane across the Sn center. Addition of 1 eq. iodoethane to complex 2 releases H₂ (g) and generates an ethyltin-capped nickel cluster with a μ₃-iodide, [Ni₃(dppm)₃(μ₃-I)(μ₃-Sn(CH₂CH₃))], 4. Notably, insertion of alkynes into the Sn-H bond of 2 can be achieved via addition of 1 eq. 1-hexyne to generate the 1-hexen-2-yl-tin-capped nickel cluster, [Ni₃(dppm)₃(μ₃H)(μ₃-Sn(C₆H₁₁))], 5. Addition of H₂ (g) to 5 regenerates the starting material, 2, and hexane. The formally 44-electron cluster 2 also displays significant redox chemistry with two reversible one-electron oxidations (E = -1.3 V, -0.8 V vs. Fc^0/+) and one-electron reduction process (E = -2.7 V vs. Fc^0/+) observed by cyclic voltammetry.