Synthesis, structure and reactivity of mu(3)-SnH capped trinuclear nickel cluster

Treatment of the trichlorotin-capped trinuclear nickel cluster, [Ni-3(dppm)(3)(mu(3)-Cl)(mu(3)-SnCl3)], 1, with 4 eq. NaHB(Et)(3) yields a mu(3)-SnH capped trinuclear nickel cluster, [Ni-3(dppm)(3)(mu(3)-H)(mu(3)-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 H-2 (g) and generates an ethyltin-capped nickel cluster with a mu(3)-iodide, [Ni-3(dppm)(3)(mu(3)-I)(mu(3)-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, [Ni-3(dppm)(3)(mu H-3)(mu(3)-Sn(C6H11))], 5. Addition of H-2 (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.