Lead Rare-Earth Oxyhalides: Syntheses and Characterization of Pb6LaO7X (X = Cl, Br)

Alkali-earth metal lead(ii) oxyhalide Ba27Pb8O8Cl54 exhibiting interesting [Pb4Ba4O4]8+ species

A novel oxyhalide Ba₂₇Pb₈O₈Cl₅₄ exhibits interesting [Pb₄Ba₄O₄]⁸⁺ species.

Two new oxyiodoplumbates: the unique 3-D hybrid oxyiodoplumbate based on neutral 2-D [Pb2I4]nlayers

The interconnection of rare neutral tetra-nuclear [Pb₄L₄] complexes and neutral 2-D [Pb₂I₄]_nlayers generates a novel 3-D hybrid oxyiodoplumbate framework.

Minerals and synthetic Pb(II) compounds with oxocentered tetrahedra: review and classification

The crystal structures of minerals and inorganic compounds with OPb4 oxocentered tetrahedra are reviewed. It is shown that the OPb4 tetrahedral units may link by sharing common Pb atoms to form structural units of various shape and dimensionality. These units determine basic topology of the structures and influence their stability and properties. The high strength of the OPb4 te trahedral units involves interplay between high basicity of additional O2– anions and stereochemical activity of the 6s 2 lone electron pairs on Pb2+ cations. The structural chemistry of polycations based upon OPb4 tetrahedra, in general, follows major trends previously observed for cation-centered tetrahedral units (silicates, phosphates, metal sulphides with MS4 tetrahedra, etc.). One may conclude that the basic structural correlations depend upon size and charge parameters of the ions only, irrespective of their positive or negative sign.

Crystal chemistry of the mendipite-type system Pb3O2Cl2—Pb3O2Br2

The crystal structures of the mendipite series Pb3O2Cl2—Pb3O2Br2have been solved by direct methods. The structures are based upon [O2Pb3]2+double chains of edge-sharing OPb4tetrahedra. There are three symmetrically independent Pb2+cations. The number of nonequivalent halogen sites is two (X1, X2). Short Pb—O bonds are located on one side of the Pb2+cations and weak Pb-X bonds are located on the other side of the Pb2+coordination sphere. The evident strong distortion of the Pb2+coordination polyhedra is due to the stereoactivity of the 6s2lone electron pairs of the Pb2+cations. Pb1-X2 and Pb2-X2 bonds are the most sensitive to the X site occupancy, which is in agreement with the non-linear behavior of theaandcparameters. Determination of unit-cell parameters by single crystal studies showed strong deviation from Vegard's rule. Nonlinearity of the lattice parameters is caused by selective ordering of the halide anions over X1 and X2 sites. Br atoms prefer the X2 position, whereas Cl prefers the X1 site. The angle between two adjacent OPb4tetrahedra was determined to analyze the influence of halogen atoms on the structure of the [O2Pb3]2+chain. Different occupancy of the X1 siteby Cl and Br atoms leads to most pronounced angular changes. These observations may be interpreted as adaptation of the [O2Pb3]2+double chains to the large halide ions in the crystal structures of the mendipite series compounds.