Synthesen und Kristallstrukturen von [Ph3PN PPh3]2[Fe2Se2(Se5)2] · 2 DMF und [Ph3PNPPh3]3[Co3 (Se4)6] · 2 DMF / Syntheses and Crystal Structures of [Ph3PN PPh3]2[Fe2Se2(Se5)2] · 2 DMF and [Ph3PNPPh3]3[Co3 (Se4)6] · 2 DMF

The title compounds have been prepared by reactions of sodium polyselenide solutions in DMF with FeCp(CO) I, and CoCl · 6H O , respectively, in the presence of (Ph PNPPh )Cl. They form black crystals, which were characterized by X-ray structure determinations. [Ph PNPPh [Fe Se (Se ] · 2 DMF: Space group P2 /c, Z = 2, 2801 observed unique reflexions, R = 0.077. Lattice dimensions at 20 °C: a = 1091.6(7), b = 1247.3(5), c = 3070(2) pm, β = 90.77(4)°. In the dimeric anion the Fe atoms are linked via two bridging Se atoms, and each Fe atom is chelated by an Se group. In the crystals, there are alternating layers o f cations and anions. [Ph PNPPh [Co (Se ] · 2 DMF : Space group P1̄, Z = 1, 3549 observed unique reflexions, R = 0.108. Lattice dimensions at 20 °C: a = 1496.2(5), b = 1504.8(5), c = 1904.1(6) pm, α = 100.31(2)°,β = 100.60(2)°, γ= 117.18(2)°. In the [Co (Se ion two [Co(Se units, each with three chelating Se groups, are linked to a central Co cation.