Alkali Metal Bismuth(III) Chloride Double Salts

Andrew W. Kelly
Aaron Nicholas
John C. Ahern
Benny Chan
Howard H. Patterson
Robert D. Pike, William & Mary

Abstract

Evaporative co-crystallization of MCl (M = Na, K, Rb, Cs) with BiOCl in aqueous HCl produces double salts: MxBiyCl(x+3yzH2O. The sodium salt, Na2BiCl5·5H2O (monoclinic P21/c, a = 8.6983(7) Å, b = 21.7779(17) Å, c = 7.1831(6) Å, β = 103.0540(10)°, V = 1325.54(19) Å3, Z = 4) is composed of zigzag chains of μ2-Cl-cis-linked (BiCl5)n2n– chains. Edge-sharing chains of NaCln(OH2)6−n octahedra (n = 0, 2, 3) are linked through μ3-Cl to Bi. The potassium salt, K7Bi3Cl16 (trigonal R−3c, a = 12.7053(9) Å, b = 12.7053(9) Å, c = 99.794(7) Å, V = 13,951(2) Å3, Z = 18) contains (Bi2Cl10)4– edge-sharing dimers of octahedra and simple (BiCl6)3– octahedra. The K+ ions are 5- to 8-coordinate and the chlorides are 3-, 4-, or 5-coordinate. The rubidium salt, Rb3BiCl6·0.5H2O (orthorhombic Pnma, a = 12.6778(10) Å, b = 25.326(2) Å, c = 8.1498(7) Å, V = 2616.8(4) Å3, Z = 8) contains (BiCl6)3– octahedra. The Rb+ ions are 6-, 8-, and 9-coordinate, and the chlorides are 4- or 5-coordinate. Two cesium salts were formed: Cs3BiCl6 (orthorhombic Pbcm, a = 8.2463(9) Å, b = 12.9980(15) Å, c = 26.481(3) Å, V = 2838.4(6) Å3, Z = 8) being comprised of (BiCl6)3– octahedra, 8-coordinate Cs+, and 3-, 4-, and 5-coordinate Cl−. In Cs3Bi2Cl9 (orthorhombic Pnma, a = 18.4615(15) Å, b = 7.5752(6) Å, c = 13.0807(11) Å, V = 1818.87(11) Å3, Z = 4) Bi octahedra are linked by μ2-bridged Cl into edge-sharing Bi4 squares which form zigzag (Bi2Cl9)n3n– ladders. The 12-coordinate Cs+ ions bridge the ladders, and the Cl− ions are 5- and 6-coordinate. Four of the double salts are weakly photoluminescent at 78 K, each showing a series of three excitation peaks near 295, 340, and 380 nm and a broad emission near 440 nm.