The crystal structure of Pb5(As3+O3)Cl7from the historic slags of Lavrion, Greece – a novel Pb(II) chloride arsenite

Abstract

AbstractThe crystal structure of new lead chloride arsenite, Pb5(As3+O3)Cl7[orthorhombic,Pbcn, a =16.894(2),b =10.913 (1),c =16.760(2) Å,V =3090.1(7) Å3], from the historic slags of Lavrion, Greece, has been solved by direct methods and refined toR1= 0.069. The structure contains five symmetrically unique Pb, one As, eight Cl and three O sites. The As atom forms three nearly equal As—O bonds which result in the formation of an AsO3trigonal pyramid with As at the apex. The Pbl. Pb2, Pb3 and Pb4 atoms are bonded to the AsO3groupsviaPb2+—O bonds to form complex [Pb4(AsO3)] chains parallel to thebaxis. The Pb(5) atom is coordinated solely by Cl–anions. The resulting Pb(5)Cl7polyhedra share common edges and corners to produce bent chains parallel to thecaxis. A short compilation of structural features of known lead chloride arsenites is given.