Excision of the {Mo6Se8} cluster core from a chevrel phase: Synthesis and properties of the first molybdenum octahedral cluster selenocyanide anions [Mo6Se8(CN)(6)](7-) and [Mo6Se8(CN)(6)](6-)

The synthesis of now molybdenum cluster sclenocyanide anionic complexes [Mo 6Se8(CN)(6)](7-) and [Mo6Se8(CN)(6)](6-) is reported. The [Mo6Se8(CN)(6)](7 -) ion was obtained by excision of the cluster core {Mo6Se8} from a Chevrel phase in the reaction of Mo,Sc, with KCN at 650 degrees C; the [Mo6Se8(CN) (6)](6-) ion is formed by oxidation of [Mo6Se8(CN)(6)](7-), New cluster sal ts K-7[Mo6Se8(CN)(6)] . 8H(2)O (1) and (Me4N)(4)K-2[Mo6Se8(CN)(6)] . 10 H2O (2) were isolated and their crystal structures were solved. Compound 1 cry stallizes in the cubic space group Fm (3) over bar m (a = 15.552(2) Angstro m, Z = 4, V = 3761.5(8) Angstrom(3)), compound 2 crystallizes in the tricli nic space group P (1) over bar (a = 11.706(2), b = 11.749(2), c = 12.459(2) Angstrom, a = 72.25(1), beta = 77.51(1), gamma = 63.04(1)degrees, Z = 1, V = 1448.5(4) Angstrom(3)). Compound 1 is paramagnetic due to an availabilit y of 21 electrons per Mo-6 cluster; cyclic voltammetry reveals a quasi-reve rsible transition [Mo6Se8(CN)(6)](7-) reversible arrow [Mo6Se8(CN)(6)](6-), E 1/2 = 0.63 V.