On tetrachlorophosphonium chlorometallates of rhenium and molybdenum:: Syntheses, crystal structures, and magnetism of [PCl4]2[Re2Cl10] and [PCl4]3[ReCl6]2, and the magnetic properties of [PCl4]2[Mo2Cl10]

MoCl4, ReCl4, and ReCl5 react with PCl5 in sealed glass ampoules at temperatures between 220 degrees and 320 degrees to [PCl4](2)[Mo2Cl10] (1) [PCl4](2)[Re2Cl10] (2), and [PCl4](3)[ReCl6](2) (3) 2 crystallizes isotypically to the previously reported 1 and the respective titanium and tin containing analogues. The structure (triclinic, P (1) over bar, Z = 1, a = 897.3(2), b = 946.0(2), c = 687.13(9) pm, alpha = 95.59(2)degrees, beta = 95.80(2)degrees, gamma = 101.07(2)degrees, V = 565.4(2) 10(6) pm(3)) is built of tetrahedral [PCl4](+) and edge sharing double octahedral [Re2Cl10](2-) ions and can be derived from a hexagonal closest packing of Cl- ions with tetrahedral and octahedral holes partially filled by P(V) and Re(IV), respectively. 3 crystallizes isotypically to [PCl4](3)[PCl6][MCl6] (M = Ti, Sn) (tetragonal, P 4(2)/mbc, Z = 4, a = 1496.2(1), c = 1363.2(2) pm). Because no evidence was found for the presence of [PCl6](-) ions, Re in 3 has to be of mixed valency with Re-IV and Re-V sharing the same crystallographic site. The structure can be derived from a cubic closest packing or alternatively from an only sparsely distorted body centered cubic arrangement of Cl- ions which is rarely found for anion arrays. The tetrahedral and octahedral holes are partially filled by PV and M-IV/V, respectively. Magnetic measurements show all three compounds to be paramagnetic and confirm the oxidation state IV for Mo and Re in 1 and 2 and the mixed valence (IV/V) for Re in 3.