Palladium Chemistry in Molten Alkali Metal Polychalcophosphate Fluxes. Synthesis and Characterization of K4Pd(PS4)2, Cs4Pd(PSe4)2, Cs10Pd(PSe4)4, KPdPS4, K2PdP2S6, and Cs2PdP2Se6

The reaction of Pd with a molten mixture of A2Qx/P2Q5/Q (A = K, Q = S, x = 3; A = Cs, Q = Se, x = 1) produced the molecular compounds K4Pd(PS4)2 (I), Cs4Pd(PSe4)2 (II), and Cs10Pd(PSe4)4 (III) and the solid-state KPdPS4 (IV), K2PdP2S6 (V), and Cs2PdP2Se6 (VI). Compounds IIII are air and water sensitive, while IVVI are air and water stable. All crystals are red or dark red except those of VI, which are black. All of them exhibit a rodlike shape. Compound I crystallizes in the triclinic space group P1̄ (No. 2) with a = 6.380(1) Å, b = 6.897(1) Å, c = 8.999(1) Å, α = 87.777(8)°, β = 81.581(8)°, γ = 84.429(9)°, and Z = 1. Compound II crystallizes in the monoclinic space group P21/c (No. 14) with a = 7.491(2) Å, b = 13.340(2) Å, c = 10.030(3) Å, β = 92.21(2)°, and Z = 2. Compound III crystallizes in the tetragonal space group P4̄2c (No. 112) with a = b = 13.949(2) Å, c = 11.527(2) Å, and Z = 4. Compound IV crystallizes in the tetragonal space group P42/mnm (No. 136) with a = b = 8.5337(2) Å, c = 10.5595(5) Å, and Z = 4. Compound V crystallizes in the orthorombic space group Pnma (No. 62) with a = 15.612(2) Å, b = 7.0724(7) Å, c = 10.080(1) Å, and Z = 4. Compound VI crystallizes in the monoclinic space group C2/c (No. 15) with a = 12.9750(4) Å, b = 8.3282(2) Å, c = 13.0568(1) Å, β = 102.940(2)°, and Z = 4. Compounds IIII contain the discrete complexes [Pd(PQ4)2]4- (Q = S, Se). The mixed salt III contains additional noncoordinating [PSe4]3- units. The structure of IV consists of Pd(II) in square planar sulfur coordination linked by edge-sharing [PS4]3- tetrahedral groups to produce one-dimensional chains. The structures of V and VI feature the [P2Q6]4- (Q = S, Se) group coordinated to the square planar Pd2+ atoms, yielding [PdP2Q6]n2n- chains. Physical characterization was performed with DTA, far-IR spectroscopy, solid-state UV/vis diffuse reflectance spectroscopy, and single-crystal optical transmission.