Three novel Pb oxyhalides, Pb3[O10Pb20](GeO4)4Cl10 (1), [O16Pb22][OPb](OH)I10(I,Br)(H2O) (2), and Pb5.5Si0.5O6Cl (3), have been prepared by high-temperature solid-state reactions (1 and 3) and hydrothermal method (2). The structure of 1 is based upon novel [O10Pb20](20+) layers of edge- and corner-sharing oxocentered OPb4 tetrahedra with cavities occupied by the GeO4 tetrahedral anions. The interlayer space contains low-occupied Pb sites and Cl(-) anions. The structure of 2 contains unique [O16Pb22][12+] layers of edge-sharing OPb4 tetrahedra with X(-) ions (X = I, Br) in and in between the layers. The structure of 3 is the first example of the Pb oxyhalide with the 3:1 ratio between the O-Pb and X sheets (X = halide). The unprecedented structure topologies and architectures observed in the title compounds are closely related to those observed in rare natural Pb oxyhalides that have no synthetic analogues to date.

[Pb10O4]Pb2(B2O5)Cl12 (1) and [Pb18O12]Pb(BO2OH)2Cl10 (2) were obtained via high-temperature high-pressure experiments. [O12Pb18](12+) and [O4Pb10](12+) oxocentered structural units of different dimensionality are excised from the ideal [OPb] layer in tetragonal α-PbO. 2 is formed with an excess of lead oxide component, and 1 is formed with an excess of borate and halide reagents. The structure of 2 can be visualized as the incorporation of {Pb(10)Cl4(BO2OH)2} clusters into alternating PbO and chloride layers, with the existence of square vacancies in both. However, the structure of 1 is described as the intrusion of [O4Pb10](12+) tetramers linked by disordered Pb(B2O5) groups into a halogen three-dimensional matrix. The structure of 2 contains 10 symmetrically independent Pb positions. The 6s(2) lone electron pair is stereochemically active on Pb(1)-Pb(9) atoms, whereas it is inert on Pb(10). All of the Pb coordinations in the structure of 2, in accordance with ECCv (volume eccentricity) parameters and the density of states (DOS), can be subdivided into three groups. The current study is the first attempt to analyze this unusual behavior in structurally complex oxyhalide material with the rare case of Pb(2+) cations, demonstrating both stereochemically active and inactive behavior of the lone pair via charge and first-principle calculations.

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Single crystals of Pb5Cu2(Te4O11)Cl8 (I) and CdCu2(Te3O8)Cl2 (II) are obtained by chemical vapor transport reactions of either a 3:1:1 mixture of CuCl2, TeO2, and PbO or a 1:2:1 mixture of CuCl2, TeO2, and CdO (evacuated quartz tube, 450→430 °C, 24 h).

Compounds (IV) and (V) are characterized by single crystal XRD and DFT calculations.

Pb oxyhalides are of interest due to their environmental and technological importance. They are also known as important constituents of oxidation zones of mineral deposits. Most Pb oxyhalides have layered α-PbO-derivative structures, which are related to the Aurivillius phases. The crystal structures of Pb-O related layered lead oxyhalides are based upon the O–Pb layers alternating with the X sheets of X– ions (X = Cl, Br, I). The PbO-derivative compounds may also incorporate a wide range of elements, including As, S, V, Mo, W, P, Si, etc., which results in interesting chemical and structural diversity and complexity. Pb3[Pb20O10](GeO4)Cl10(1) was obtained by rapid quenching of lead-oxyhalide melt [1]. The structure of 1 (Cmca, a = 28.352(19), b = 11.116(7), c = 16.513(11) Å, V = 5204(6) Å3, R1 = 0.0504) contains 7 symmetrically independent Pb sites. Pb(6) site is splitted into less occupied Pb6A and Pb6B sites. The coordination environments of the Pb atoms are variable in agreement with the presence of stereochemically active "lone pairs" on divalent lead cations. The structure of 1 contains one Ge site coordinated tetrahedrally by four O atoms with the average <Ge-O> bond length equal to 1.75 Å. The total number of oxygen sites is seven. The O(3), O(4), O(6), and O(7) sites are bonded to Ge, whereas other O atoms (O(1), O(2), O(5)) are tetrahedrally coordinated by Pb atoms, which results in formation of oxocentered OPb4tetrahedra. 1 belongs to the 1:1 type and consists of alternating PbO-type layers and mixed Pb–Cl sheets oriented parallel to (100). The PbO-type layer is a derivative of the [OPb] tetrahedral layer in α-PbO and can be obtained from the latter by removal of blocks of oxocentered tetrahedra. The GeO4tetrahedral anions locate in the cavities within the PbO-type layer. The formula of the layer can be written as [O10Pb20]2°+. The structure of 1 illustrates the complexity of the lead oxyhalide systems and validates new pathways for synthesis of complex Pb oxyhalides.

Synthesis and Modular Structural Architectures of Mineralogically Inspired Novel Complex Pb Oxyhalides. -The crystal structures of compounds (IV), (VII), and (IX) are determined by single crystal XRD. (IV) crystallizes in the orthorhombic space group Cmca. Its structure contains novel [O10Pb20] 20+ layers of edge-and corner-sharing OPb4 tetrahedra with cavities occupied by [GeO4] 4tetrahedral anions. (VII) crystallizes in the tetragonal space group I4/m. It is the first example of a Pb oxyhalide with a 3:1 ratio between O-Pb and X sheets (X: halide). (IX) crystallizes in the orthorhombic space group Pmn21. The structure contains [O16Pb22] 12+ layers of edge-sharing OPb4 tetrahedra with X -(X: I, Br) ions in and between the layers. -(SIIDRA*, O. I.; ZINYAKHINA, D. O.; ZADOYA, A. I.; KRIVOVICHEV, S. V.; TURNER, R. W.; Inorg. Chem. 52 (2013) 21, 12799-12805, http://dx.

Pb carbonate minerals containing additional hydroxyl groups receive considerable attention due to their importance to the environment. These phases widely form as lead corrosion technological products. Majority of Pb hydroxocarbonates demonstrate layered structural architectures and include: hydrocerussite, plumbonacrite and recently discovered grootfonteinite, abellaite and NaPb 5 (OH) 3 (CO 3) 4 mineral phase from Lavrion slags. There were several reports on hydrocerussite physical properties and chemistry previously (e.g. Anthony et al., 2003; Olby, 1966). Structural data on powdery synthetic samples of '2PbCO 3 •Pb(OH) 2 ' were reported in Marinetto et al., 2002. However single-crystal X-ray data for natural samples of layered Pb hydroxocarbonates were unavailable till very recent time. We have worked with many samples of "hydrocerussite" from several localities within our ongoing projects on Pb 2+ oxysalts crystal chemistry: Merehead quarry, England; Långban, Sweden; Lavrion, Greece; Kombat, Namibia. Structural studies allowed identification of grootfonteinite from Kombat and unknown yet as a mineral NaPb 5 (OH) 3 (CO 3) 4 from Lavrion slags. Several different polytypes for hydrocerussites from Merehead were also identified. Each of above mentioned Pb hydroxocarbonates demonstrates unique but related structure type, which in turn can be transformed via various mechanisms one to each other.