Kalium-Thio/Oxo-Vanadate(V) K3[VSxO4–x] (x = 1–4) und Na3[VSO3]: Synthese, Strukturchemie, Eigenschaften

Abstract

The mixed potassium thio/oxo-orthovanadates(V) of the series K3[VSxO4−x] (x = 1, 2, 2.6, 3.4-4) and the sodium compound Na3[VSO3] have been prepared in evacuated silica ampoules at reaction temperatures of 450 to 600 °C starting from stoichiometric amounts of an alkali oxovanadate, the alkali sulfide and (where necessary) elemental vanadium and sulfur. The crystal structures (determined on the basis of X-ray single-crystal data) of the yellow compounds Na3[VSO3] (space group R3c, a = 863.3(3), c = 1234.7(3) pm, Z = 6, R1 = 0.0170) and K3[VSO3] (space group P21/m, a = 659.0(3), b = 589.5(3), c = 879.3(3) pm, β = 102.12(3)°, Z = 2, R1 = 0.0907) both contain isolated monothio-vanadate ions [VSO3]3−. The orange crystals of K3[VS2O2] (space group P21/m, a = 1056(2), b = 732.2(10), c = 1167(2) pm, β = 121.86(11)°, Z = 4, R1 = 0.0977) as well as the red phase K3[VS2.6O1.4] (space group P21/c, a = 1009.1(6), b = 681.2(4), c = 1190.1(8) pm, β = 93.55(1)°, Z = 4, R1 = 0.0929) also crystallize with new, singular, monoclinic structure types, which are nevertheless structurally related, as indicated by the similar lattice parameters. Starting from K3[VS4], a phase width up to the composition K3[VS3.4O0.6] (space group Pnma, a = 909.5(3), b = 1035.6(5), c = 895.6(6) pm, Z = 4, R1 = 0.0948) is observed in addition. Structure and bonding in this new series of potassium compounds are discussed and compared with those in the respective sodium phases, including aspects like anion geometry and dynamics (as observed by Raman spectroscopy), packing in the crystals, UV/Vis spectroscopy and FP-LAPW band structure calculations.