Crystal structure of synthetic Pb (sub 4.32) Sb (sub 3.68) S (sub 8.68) Cl (sub 2.32) ; a chlorine-bearing alternative to Pb (sub 4) Sb (sub 4) S (sub 11)

This new chlorine sulphosalt was prepared at 500 degrees C by gas transport reaction; EPMA gave Pb 50.7, Sb 27.3, S 17.0, Cl 4.5, = 99.5. It has a 15.04, b 15.51, c 4.09 Aa, V 954.1 Aa, Z = 2; space group Pbam; D 5.83 g/cm (super 3) . X-ray single-crystal data and refinement to R 0.039 shows that this compound is isopointal to Pb (sub 4) Sb (sub 4) S (sub 11) . The special position 0,0,1/2 is entirely occupied by Cl; other Cl atoms partially substitute in specific S positions, in connection to (Pb,Sb) sites according to the scheme Pb (super 2+) + Cl (super -) ->> Sb (super 3+) + S (super 2-) . It is possible that the planar Pb (sub 4) Cl group plays a key structure-determining role in the formation of high Cl-bearing Pb-Sb sulphosalts.