Heavy Neutral and Anionic Pnictogen Thiocyanates.

When [PPN]SCN (1; PPN = [Ph3P-N-PPh3]) is treated with Me3Si-SCN in methanol, [PPN][H(NCS)2] (2), a hydrogen diisothiocyanate salt bearing the [H(NCS)2]- anion, was generated, isolated, and fully characterized. Pure heavy E(NCS)3 [E = Sb (3), Bi (4)] species were obtained from the reaction of EF3 and an excess of Me3Si-SCN, while the tetrahydrofuran (THF) solvates E(NCS)3·THF were isolated when the product was recrystallized from THF. When 2 equiv of 1 was combined with Me3Si-SCN and SbF3, [PPN]2[Sb(NCS)5] (5) could be isolated. When 1 was added to BiF3, [PPN]2[Bi(NCS)3(SCN)2·THF] (6·THF), containing three SCN- ions coordinating via the N atom and two coordinating via the S atom, was isolated after recrystallization from THF. The structures of 1, 2, 3·THF, 4·THF, 5, and 6·THF were determined. 3·THF displayed a typical [3 + 3] coordination mode with a trigonal-pyramidal environment in the first coordination sphere of the Sb3+ ion, and the dianion of 5, [Sb(NCS)5]2-, featured a classical square-pyramidal molecular geometry around the Sb3+ ion with one additional Menshutkin-type interaction to one aryl ring of the [PPN]+ cation. 4·THF exhibited a distorted pentagonal-bipyramidal structure within a two-dimensional network, while in 6·THF, an octahedrally surrounded Bi3+ ion was observed.