[Mn2(AsS4)4]8- and [Cd2(AsS4)2(AsS5)2]8-: discrete clusters with high negative charge from alkali metal polythioarsenate fluxes.

The reaction of Mn and Cd in alkali metal polythioarsenate fluxes afforded four new compounds featuring molecular anions. K(8)[Mn(2)(AsS(4))(4)] (I) crystallizes in the monoclinic space group P2/n with a = 9.1818(8) A, b = 8.5867(8) A, c = 20.3802(19) A, and beta = 95.095(2) degrees. Rb(8)[Mn(2)(AsS(4))(4)] (II) and Cs(8)[Mn(2)(AsS(4))(4)] (III) both crystallize in the triclinic space group P1 with a = 9.079(3) A, b = 9.197(3) A, c = 11.219(4) A, alpha = 105.958(7) degrees, beta = 103.950(5) degrees, and gamma = 92.612(6) degrees for II and a = 9.420(5) A, b = 9.559(5) A, c = 11.496(7) A, alpha = 105.606(14) degrees, beta = 102.999(12) degrees, and gamma = 92.423(14) degrees for III. The discrete dimeric [Mn(2)(AsS(4))(4)](8-) clusters in these compounds are composed of two octahedral Mn(2+) ions bridged by two [AsS(4)](3-) units and chelated each by a [AsS(4)](3-) unit. Rb(8)[Cd(2)(AsS(4))(2)(AsS(5))(2)] (IV) crystallizes in P1 with a = 9.122(2) A, b = 9.285(2) A, c = 12.400(3) A, alpha = 111.700(6) degrees, beta = 108.744 degrees, and gamma = 90.163(5) degrees. Owing to the greater size of Cd compared to Mn, the Cd centers in this compound are bridged by [AsS(5)](3-) units. The [Cd(2)(AsS(4))(4)](8-) cluster is a minor component cocrystallized in the lattice. These compounds are yellow in color and soluble in water.