Chemistry of gold in molten alkali metal polychalcophosphate fluxes. Synthesis and characterization of the low-dimensional compounds A(3)AuP(2)Se(8) (A=K, Rb, Cs), A(2)Au(2)P(2)Se(6) (A=K, Rb), A(2)AuPS(4) (A=K, Rh, Cs), and AAuP(2)S(7) (A=K, Rb)

The reaction of Au with a molten mixture of A(2)Q/P(2)Q(5)/Q (Q = S, Se) produced the quaternary compounds A(3)AuP(2)Se(8) (A = K, Rb, Cs) (I-III), A(2)Au(2)P(2)Se(6) (A = K, Rb) (IV, V), A(2)AuPS(4) (A = K, Rb, Cs) (VI-VIII), and AAuP(2)S(7) (A = K, Rb) (IX-X). I-III crystalline in the acentric space group Cc (No. 9): I, a = 7.122(2) Angstrom, b = 12.527(3) Angstrom, c = 18.666(4) Angstrom, beta = 96.06(2)degrees, Z = 4. IV and V crystallize in the space group C2/m (No. 12): IV, a = 12.289(2) Angstrom, b = 7.210(1) Angstrom, c = 8.107(1) Angstrom, beta = 115.13(1)degrees, Z = 2. VI and VII crystallize in the space group P2(1)/m (No. 11): VI, a = 6.518(2) Angstrom, b = 6.747(2) Angstrom, c = 9.468(3) Angstrom, beta = 92.98(2)degrees, Z = 2. VIII crystallizes in the space group Pbcm (No. 57) with a = 6.904(3) Angstrom, b = 20.093(6) Angstrom, c = 7.025(5) Angstrom, and Z = 4. IX and X crystallize in the space group C2/c (No. 15): IX, a = 7.917(3) Angstrom, b = 9.247(2) Angstrom, c = 14.968(3) Angstrom, beta = 91.84(9)degrees, Z = 4. Compounds I-III have a one-dimensional structure with [AuP2Se8](n)(3n-) chains separated by A(+) cations. The monovalent Au cation is linearly coordinated to the new ligand [P2Se8](4-). IV and V possess a one-dimensional structure with [Au2P2Se6](n)(2n-) chains separated by A(+) ions. The monovalent Au cation is linearly coordinated to ethane like [P2Se6](4-) ligands. VI and VII have a one-dimensional structure with [AuPS4](n)(2n-) chains separated by A(+) cations. The Au+ cation is linearly coordinated to alternating [PS4](3-) tetrahedra. The structure of VIII is related to that of I-III with [AuPS4](n)(2n-) chains. the diselenide of the [P2Se8](4-) unit is replaced by a second, essentially linear, S-Au-S linkage leaving the structure of the chain unchanged. IX and X have the [AuP2S7](n-) chains with square planar Au3+ centers. The compounds were characterized with differential thermal analysis, far-IR, Raman spectroscopy, solid-state UV/vis diffuse reflectance spectroscopy, and single-crystal optical spectroscopy. Cs2AuPS4, at T > 375 degrees C, converts to beta-Cs2AuPS4, which is isostructural to K2AuPS4.