Crystal chemistry of lead oxide chlorides. II. Crystal structure of Pb7O4(OH)4Cl2
Krivovichev, Sergey V.; Burns, Peter C.
European Journal of Mineralogy Volume 14 Number 1 (2002), p. 135 - 139
published: Jan 28, 2002
ArtNo. ESP147051401014, Price: 29.00 €
The crystal structure of Pb7O4(OH)4Cl2 (monoclinic, C1121, a = 5.791(2), b = 12.998(4), c = 19.330(6) Å, γ = 90.089(3)o, V = 1455.1(8) Å3) has been solved by direct methods and refined to R1 = 0.061 using X-ray diffraction data collected from a crystal twinned on (010). There are seven symmetrically independent Pb2+ cations in the structure. Each has a strongly distorted coordination polyhedron due to stereochemically active s2 lone electron pairs on the Pb2+ cations. The structure is based on [O2Pb3] double chains extending along  formed by edge-sharing (OPb4) oxocentered tetrahedra. Hydroxyl groups form two short (OH)-Pb bonds that result in (OH)Pb2 dimers. The (OH)Pb2 dimers link the [O2Pb3] chains into a three-dimensional framework with channels parallel to  that are occupied by Cl- anions.