A new family of compounds with tetrahedral anions: PbnBiOn(XO4), X = V,P, As,n = 1, 2, 4. A comparison with lead oxysulfates PbnPbOn(SO4)

The thermal behavior and crystallographic characteristics of nine compounds, Pb_nMO_n(XO₄) with M = Bi, Pb, X = V, P, As, S and n = 1, 2, 4, are reported. A previously reported γ phase for Pb₂BiO₂(VO₄) was shown to consist of a mixture of PbBiO(VO₄) and Pb₄BiO₄(VO₄) that resulted from a kinetically controlled decomposition of Pb₂BiO₂(VO₄) at elevated temperatures. The relationship between the α, β and δ transitions for Pb₂BiO₂(VO₄) was clarified. All of these phases contain the tetrahedral anion XO₄ that imparts thermal and structural similarities as well as specifications that can be ascribed to anion size differences.     

The electronic structures of vanadate salts: Cation substitution as a tool for band gap manipulation

The electronic structures of six ternary metal oxides containing isolated vanadate ions, Ba₃(VO₄)₂, Pb₃(VO₄)₂, YVO₄, BiVO₄, CeVO₄ and Ag₃VO₄ were studied using diffuse reflectance spectroscopy and electronic structure calculations. While the electronic structure near the Fermi level originates largely from the molecular orbitals of the vanadate ion, both experiment and theory show that the cation can strongly influence these electronic states. The observation that Ba₃(VO₄)₂ and YVO₄ have similar band gaps, both 3.8 eV, shows that cations with a noble gas configuration have little impact on the electronic structure. Band structure calculations support this hypothesis. In Pb₃(VO₄)₂ and BiVO₄ the band gap is reduced by 0.9-1.0 eV through interactions of (a) the filled cation 6s orbitals with nonbonding O 2p states at the top of the valence band, and (b) overlap of empty 6p orbitals with antibonding V 3d-O 2p states at the bottom of the conduction band. In Ag₃VO₄ mixing between filled Ag 4d and O 2p states destabilizes states at the top of the valence band leading to a large decrease in the band gap (E_g=2.2 eV). In CeVO₄ excitations from partially filled 4f orbitals into the conduction band lower the effective band gap to 1.8 eV. In the Ce_1−xBi_xVO₄ (0≤x≤0.5) and Ce_1−xY_xVO₄ (x=0.1, 0.2) solid solutions the band gap narrows slightly when Bi³⁺ or Y³⁺ are introduced. The nonlinear response of the band gap to changes in composition is a result of the localized nature of the Ce 4f orbitals.     

Homoleptic Zinc(II) Complexes Based on 4′‐(2‐Thienyl)‐terpyridine: Preparation,Structures, and Properties

The homoleptic complexes Zn^II(4′‐(2‐(5‐R‐thienyl))‐terpyridine)₂(ClO₄)₂ [R = hydrogen ( 1 ), bromo ( 2 ), methyl ( 3 ), and methoxy ( 4 )] were prepared. Their structures were determined by single‐crystal X‐ray diffraction analyses, and further characterized by high resolution mass, infrared spectra (IR), and elemental analyses. Single crystal X‐ray diffraction analysis showed that Zn^II ions in the complexes are both six‐coordinate with N₆ coordination sphere, displaying distorted octahedral arrangements. The absorption and emission spectra of the homoleptic Zn^II complexes were investigated and compared to those of the parent complex Zn^II(4′‐(2‐thienyl))‐terpyridine)₂(ClO₄)₂. The UV/Vis absorption spectra showed that the complexes all exhibit strong absorption component in UV region, moreover, complex 4 has an absorption component in the visible region. Thus, the photocatalytic activities of the complexes in degradation of organic dyes were investigated under UV and visible irradiation.     

Einige Cadmiumapatite sowie die Verbindungen Cd2XO4F mit X = P,As und V

The Cadmiumapatites Cd₅(PO₄)₃OH und Cd₅(PO₄)₃F as well as the yet unknown iodoapatite Cd₅(VO₄)₃I were synthesized and investigated by X-ray powder and single crystal methods. All single crystal diagrams exhibit hexagonal symmetry. The iodine compound has such a low c constant (about 6.5 Å) that is seems essential to discuss the halide positions in the structure. The reflexions of Cd₅(PO₄)₃F show splitting which is indicative of a triclinic distortion of the apatite structure and of twinning. At about 150–350°C the deformation disappears reversibly. Cd₅(AsO₄)₃F, Cd₅(VO₄)₃F and the corresponding OH-compounds could not be prepared, but the new isotypic compounds Cd₂XO₄F (X = P, As, V) were synthesized by thermal and hydrothermal reactions. Single crystal investigations and the morphology of Cd₂PO₄F proved the space group C2/c. There are structural relations to the minerals of the wagnerite group. In connexion with the synthesis of Cd₂XO₄F a discussion of the relative stabilities of different apatites is given.     

Visible‐Light‐Activated C−C Bond Cleavage and Aerobic Oxidation of Benzyl Alcohols Employing BiMXO5 (M=Mg,Cd, Ni,Co, Pb,Ca and X=V,P)

The synthesis, structure, optical and photocatalytic studies of a family of compounds with the general formula, BiMXO₅; M=Mg, Cd, Ni, Co, Pb, Ca and X=V, P is presented. The compounds were prepared by regular solid‐state reaction of constituents in the temperature range of 720–810 °C for 24 h. The compounds were characterized by powder X‐ray diffraction (PXRD) methods. The Rietveld refinement of the PXRD patterns have been carried out to establish the structure. The optical absorption spectra along with the colors in daylight have been explained employing the allowed d‐d transition. In addition, the observed colors of some of the V⁵⁺ containing compounds were explained using metal‐to‐metal charge transfer (MMCT) from the partially filled transition‐metal 3d orbitals to the empty 3d orbitals of V⁵⁺ ions. The near IR (NIR) reflectivity studies indicate that many compounds exhibit good NIR reflectivity, suggesting that these compounds can be employed as ‘cool pigments’. The experimentally determined band gaps of the prepared compounds were found to be suitable to exploit them for visible light activated photocatalysis. Photocatalytic C?C bond cleavage of alkenes and aerobic oxidation of alcohols were investigated employing visible light, which gave good yields and selectivity. The present study clearly demonstrated the versatility of the Paganoite family of compounds (BiMXO₅) towards new colored inorganic materials, visible‐light photocatalysts and ‘cool pigments’.     

Synthesis and Crystal Structure of a Novel Polymeric Lead(II) Compound: [Pb2(phen)2(N3)3(ClO4)]n

A 2D lead(II) coordination polymer [Pb₂(phen)₂(N₃)₃(ClO₄)]_n,( 1 ) containing 1,10‐phenanthroline (phen) and two different anions, has been synthesized and characterized by elemental analysis, IR and ¹H NMR spectroscopy and X‐ray crystallography. The single‐crystal X‐ray data show two different kinds of Pb²⁺ ions with coordination numbers of eight, Pb1 = PbN₆O₂ and Pb2 = PbN₈, with hemidirected and holodirected structures, respectively. The supramolecular features in 1 is negiotated through the weak but directional C‐H···O and C‐H···N interactions and aromatic π–π stacking interactions.     

One‐Dimensional Holodirected Lead(II) Coordination Polymer, [Pb(μ2‐TPPZ)(NO3)(ClO4)]n (TPPZ = 2, 3, 5, 6–tetra(2‐pyridyl)pyrazine)

A lead(II) complex with 2,3,5,6‐tetra(2‐pyridyl)pyrazine (TPPZ), nitrate, and perchlorate ligands has been synthesized and characterized by CHN elemental analysis and IR and ²⁰⁷Pb NMR spectroscopy. The single crystal X‐ray data of the [Pb₂(μ‐TPPZ)₂(NO₃)₂(ClO₄)₂] compound show that the complex is a one‐dimensional coordination polymer and that the Lead atom has a less‐common, ten‐coordinate holodirected geometry.     

Synthesis and crystal structure of 2‐amino‐3‐hydroxypyridinium dioxido(pyridine‐2,6‐dicarboxylato‐κ3O2,N,O6)vanadate(V) and its conversion to nanostructured V2O5

2‐Amino‐3‐hydroxypyridinium dioxido(pyridine‐2,6‐dicarboxylato‐κ³O²,N,O⁶)vanadate(V), (C₅H₇N₂O)[V(C₇H₃NO₄)O₂] or [H(amino‐3‐OH‐py)][VO₂(dipic)], (I), was prepared by the reaction of VCl₃ with dipicolinic acid (dipicH₂) and 2‐amino‐3‐hydroxypyridine (amino‐3‐OH‐py) in water. The compound was characterized by elemental analysis, IR spectroscopy and X‐ray structure analysis, and consists of an anionic [VO₂(dipic)]⁻ complex and an H(amino‐3‐OH‐py)⁺ counter‐cation. The V^V ion is five‐coordinated by one O,N,O′‐tridentate dipic dianionic ligand and by two oxide ligands. Thermal decomposition of (I) in the presence of polyethylene glycol led to the formation of nanoparticles of V₂O₅. Powder X‐ray diffraction (PXRD) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of the synthesized powder.     

A Series of Isolable Silanoic Thio‐, Seleno‐, and Telluroesters (LSi(X)OR) with Donor‐Supported SiX Double Bonds (L=β‐Diketiminate; X=S,Se, Te)

The first silicon analogues of carbonic (carboxylic) esters, the silanoic thio‐, seleno‐, and tellurosilylesters 3 (Si?S), 4 (Si?Se), and 5 (Si?Te), were prepared and isolated in crystalline form in high yield. These thermally robust compounds are easily accessible by direct reaction of the stable siloxysilylene L(Si:)OSi(H)L′ 2 (L=HC(CMe)₂[N(aryl)₂], L′=CH[(C?CH₂)‐CMe][N(aryl)]₂; aryl=2,6‐iPr₂C₆H₃) with the respective elemental chalcogen. The novel compounds were fully characterized by methods including multinuclear NMR spectroscopy and single‐crystal X‐ray diffraction analysis. Owing to intramolecular N→Si donor–acceptor support of the Si?X moieties (X=S, Se, Te), these compounds have a classical valence‐bond N⁺–Si–X^? resonance betaine structure. At the same time, they also display a relatively strong nonclassical Si?X π‐bonding interaction between the chalcogen lone‐pair electrons (n_π donor orbitals) and two antibonding Si? N orbitals (σ*_π acceptor orbitals mainly located at silicon), which was shown by IR and UV/Vis spectroscopy. Accordingly, the Si?X bonds in the chalcogenoesters are 7.4 ( 3 ), 6.7 ( 4 ), and 6.9 % ( 5 ) shorter than the corresponding Si? X single bonds and, thus, only a little longer than those in electronically less disturbed Si?X systems (“heavier” ketones).     

Synthesis of Pb9(PO4)6/Ag3PO4 Composite Photocatalysts with Enhanced Visible Light Photocatalytic Activity

Pb₉(PO ₄)₆/Ag₃PO ₄ photocatalysts with different amounts of Pb₉(PO ₄)₆ were successfully synthesised by the ion exchange method. The catalysts were characterized by X‐ray diffractometry (XRD ), High‐resolution transmission electron microscopy (HRTEM ), X‐ray photoelectron spectroscopy (XPS ), Brunauer– Emmett–Teller (BET ), Fourier transform infrared spectrometry (FT ‐IS ), and ultraviolet‐visible (UV ‐vis) spectroscopy. All Pb₉(PO ₄)₆/Ag₃PO ₄ photocatalysts show much higher photocatalytic activities than pure Ag₃PO ₄ under visible light irradiation in the methyl‐orange (MO ) decomposition. Especially, the 3.0 wt% Pb₉(PO ₄)₆/Ag₃PO ₄ photocatalyst shows the highest photoactivity and also high stability after five cycles. The MO degradation rate during each cycle is almost maintained at 97%. Photo‐electrochemical measurement of photocatalysts verified that the enhancing photocatalytic activity was resulted from the electron‐hole pair high separation. The photocatalytic activity enhancement of Pb₉(PO ₄)₆/Ag₃PO ₄ is closely related to , the main active oxygen species.     

Topologisch und elektronisch bemerkenswerte „reduzierte”︁ Cluster des Typs [V18O42(X)]n− (X = SO4, VO4) mit Td-Symmetrie und davon abgeleitete Cluster [V(18–p)As2pO42(X)]m− (X = SO3, SO4, H2O; p = 3, 4)

Reduced Clusters with Remarkable Topological and Electronic Properties of the Type of [V₁₈O₄₂(X)]^n? (X = SO₄, VO₄) with T_d-Symmetry and Related Clusters [V_(18—p)As_2pO₄₂(X)]^m? (X = SO₃, SO₄, H₂O; p = 3, 4) The novel cluster-compounds Na₆[V₁₈O₄₂H₉(VO₄)] · 21 H₂O, (NH₄)₈[V₁₈O₄₂(SO₄)] · 25 H₂O, K₆[V₁₅As₆O₄₂(H₂O)] · 8 H₂O, (NH₄)₆[V₁₄As₈O₄₂(SO₃)], (NH₄)₆[V₁₄As₈O₄₂(SO₄)] and [N(CH3)₃]₄[₄V₁₄As₈0₄₂(H₂0)] were prepared and characterized by IR- and UV/Vis/NIR-spectroscopy, magnetic measurements and complete crystal structure analysis. For structural data see Inhaltsübersicht. Topological relations to the rhombicuboctahedron spanned by 24 0-atoms of the genuine hypothetical a-Keggin ion, at which the square planes are capped by V?O or As₂O groups, are discussed. Of particular interest are the ?extended”? Keggin ions [V₁₈O₄₂(X)]ⁿ- (X = SO₄ VO₄), (formaly derived from the hypothetical genuine a-Keggin ion by addition of six V?O groups) which have quite different electron populations in spite of the same structure of their cluster shells.     

Syntheses and Characterization of Mixed‐Anions Lead(II) Complexes, [Pb(phen)2(CH3COO)]X (X=NCS—, NO3— and ClO4—), Crystal Structure of [Pb(phen)2(CH3COO)](ClO4)

The 1:2 adduct lead(II) complexes with 1, 10‐phenanthroline (phen) containing three different anions, [Pb(phen)₂(CH₃COO)X] (X=NCS^—, NO₃^— and ClO₄^—), have been synthesized and characterized by CHN elemental analysis, IR‐, ¹H‐ and ¹³C NMR spectroscopy. The structure of [Pb(phen)₂(CH₃COO)(ClO₄)] was determined by single crystal X‐ray analysis. The Pb atom of the monomeric complex is coordinated by four nitrogen atoms of two 1, 10‐phenanthroline ligands and two oxygen atoms of the acetate ligand to form an irregular octahedron. The arrangement of the 1, 10‐phenanthroline and acetate ligands, exhibits a coordination gap around the Pb^II ion, possibly occupied by a stereochemical electron active lone pair on lead(II), which results in a hemidirected lead compound. The π‐π stacking interaction between the parallel aromatic rings may help to increase the coordination ‘gap’ around the Pb^II ion.     

Design and Syntheses of Three Novel Carbonate Halides: Cs3Pb2(CO3)3I,KBa2(CO3)2F,and RbBa2(CO3)2F

Three new carbonate halides, Cs₃Pb₂(CO₃)₃I, KBa₂(CO₃)₂F and RbBa₂(CO₃)₂F have been synthesized with hydrothermal and solid‐state methods. Cs₃Pb₂(CO₃)₃I is the first product in the lead carbonate iodides family; KBa₂(CO₃)₂F and RbBa₂(CO₃)₂F are the first two centrosymmetric compounds found in the alkaline–alkaline earth carbonate fluorides family. Cs₃Pb₂(CO₃)₃I crystallizes in a centrosymmetric space group C2/m, and exhibits a two‐ dimensional layered structure which is formed by [Cs₄Pb₄(CO₃)₆I₂]_∞ double‐layers consisting of [Pb₂(CO₃)₃I]_∞ single‐layers bridged by the Cs atoms. KBa₂(CO₃)₂F and RbBa₂(CO₃)₂F, which are isostructural, crystallize in a trigonal crystal system with a centric space group of R featuring a honeycomb‐like framework. First principle calculations indicate that Cs₃Pb₂(CO₃)₃I has a moderate birefringence and explain the difference between the band gaps of the title compounds from electron structures. The effects of cations and halogens on the structures and properties of the title compounds are also discussed.     

Expanded Analogs of Three-Dimensional Lead-Halide Hybrid Perovskites

Replacing the Pb−X octahedral building unit of A^IPbX₃ perovskites (X=halide) with a pair of edge-sharing Pb−X octahedra affords the expanded perovskite analogs: A^IIPb₂X₆. We report seven members of this new family of materials. In 3D hybrid perovskites, orbitals from the organic molecules do not participate in the band edges. In contrast, the more spacious inorganic sublattice of the expanded analogs accommodates larger pyrazinium-based cations with low-lying π* orbitals that form the conduction band, substantially decreasing the band gap of the expanded lattice. The molecular nature of the conduction band allows us to electronically dope the materials by reducing the organic molecules. By synthesizing derivatives with A^II=pyridinium and ammonium, we can isolate the contributions of the pyrazinium-based orbitals in the band gap transition of A^IIPb₂X₆. The organic-molecule-based conduction band and the inorganic-ion-based valence band provide an unusual electronic platform with localized states for electrons and more disperse bands for holes upon optical or thermal excitation.     

Structural and physicochemical characterization of zinc(II) and cadmium(II) complexes with 1,4‐dimethy‐lhomopiperazine

In order to know the relationship between structures and physicochemical properties of Group 12 metal(II) ions, the complexes with ‘simple’ ligands, such as alkyl cyclic diamine ligand and halide ions, were synthesized by the reaction of 1,4‐dimethylhomopiperazine (hp′) with MX₂ as metal sources (M = Zn, Cd; X = Cl, Br, I). The five structural types, [ZnX₂(hp′)] (X = Cl ( 1 ), Br ( 2 ) and I ( 3 )), [ZnX₃(Hhp′)] (X = Cl ( 1′ ) and Br ( 2′ )), [CdCl₂(hp′)]_n ( 4 ), [{CdCl₂(Hhp′)}₂(µ‐Cl)₂] ( 4′ ) and [{CdX(hp′)}₂(µ‐X)₂] (X = Br ( 5 ), I ( 6 )), were determined by X‐ray analysis. The sizes of both metal(II) and halide ions and the difference in each other's polarizability influence each structure. All complexes were characterized by IR, far‐IR, Raman and UV–Vis absorption spectroscopies. In the far‐IR and Raman spectra, the typical ν(M N) and ν(M X) peaks clearly depend on the five structural types around 540–410 cm⁻¹ and 350–160 cm⁻¹ respectively. The UV–Vis absorption band energy around 204–250 nm also reflects each structural type. Copyright © 2005 John Wiley & Sons, Ltd.     

Isomorphism and phase diagram of the Pb5(PO4)3Cl-Pb5(VO4)3Cl system

Compounds of composition Pb₅(P _x V_1−x O₄)₃Cl (0 ≤ x ≤ 1), which are synthetic analogues of minerals pyromorphite, vanadinite, and endlichite, were synthesized for the first time by high-temperature solid-phase reactions. X-ray diffraction and IR spectroscopy were used to determine the structure of the compounds and revealed complete miscibility in the solid phase of the Pb₅(PO₄)₃Cl-Pb₅(VO₄)₃Cl binary system. Adiabatic reaction calorimetry was used to determine standard enthalpies of mixing and formation and showed that the regular solutions model is applicable to the Pb₅(PO₄)₃Cl-Pb₅(VO₄)₃Cl system. Differential thermal analysis in tandem with high-temperature X-ray diffraction was used to study the phase diagram and characterize phase transitions.     

Synthesis,Crystal Structure,and Visible Light Responses of Ti4Cu4-Oxo Clusters with Mixed Valence Copper Ions

Summaryof main observation and conclusion In order to extend the absorption spectrum of polyoxo-titanium clusters into the visible region,two new heterometal-oxo clusters Ti4CuII2CuI2(μ3-O)6(benzoate)10(MeCN)4(PTC-153)and Ti4CuII2CuI2(μ3-O)6(benzoate)8(CH3COO)2(MeCN)4(PTC-154)were success-fully synthesized.Single-crystal X-ray diffraction and X-ray photoelectron spectroscopy studies showed that these two heterometallic Ti4Cu4-oxo clusterspossessed Chinese knot-shape structure and mixed valence Cu^1+/2+ions.UV-visible spectroscopyanalysis demonstrated that the visible light region ab-sorption of PTC-153and PTC-154 could be significantly enhanced by doping copper.Furthermore,their visible-light driven photocurrent responses were studied by using samples of PTC-153and PTC-154as electrode precursors.     

Between MOFs and molecules: organolead(IV) compounds with chain structures

Organolead compounds are of interest mainly as catalysts and organolead halides have proved to be very efficient materials for solar cells. Two organolead(IV) dimethylarsinates, namely catena‐poly[[triphenyllead(IV)]‐μ‐chlorido‐[triphenyllead(IV)]‐μ‐dimethylarsinato‐κ²O:O′], [Pb₂(C₆H₅)₆(C₂H₆AsO₂)Cl]_n or [(Ph₃Pb)₂Cl(O₂AsMe₂)], ( 1 ), and poly[chlorido(μ₃‐dimethylarsinato‐κ³O:O,O′:O′)diphenyllead(IV)], [Pb(C₆H₅)₂(C₂H₆AsO₂)Cl]_n or [(Ph₂ClPb)(O₂AsMe₂)], ( 2 ), together with the triphenyllead(IV) diphenylphosphinate catena‐poly[[triphenyllead(IV)]‐μ‐diphenylphosphinato‐κ²O:O′], [Pb(C₆H₅)₃(C₁₂H₁₀O₂P)]_n or [(Ph₃Pb)(O₂PPh₂)], ( 3 ), have been synthesized and characterized by single‐crystal X‐ray diffraction, IR spectroscopy and mass spectrometry. In ( 1 ), a chain structure was found with alternating chloride and Pb—O—As—O—Pb arsinate bridges between five‐coordinate Pb^IV atoms. In ( 2 ), bidentate and chelate‐like bonded dimethylarsinate ligands form double chains with heptacoordinated Pb^IV atoms. In ( 3 ), a pentacoordinated Pb^IV atom is connected by Pb—O—P—O—Pb phosphinate bridges to form a linear chain. Obviously, the steric demand of the phenyl ligands at Pb^IV reduces the possibility of interconnections via polydentate ligands to one dimension only. Thus, no metal–organic frameworks (MOF) are formed but instead various chain structures are observed.     

Synthesis,crystal and electronic structure,anticancer activity of ruthenium(II) arene complexes with thiosemicarbazones

A series of half‐sandwich ruthenium(II) arene complexes [(η⁶‐p‐cymene)Ru^II(R‐BzTSC)Cl]Cl 1 , 2 , 3 (BzTSC = benzaldehyde thiosemicarbazone and R = H, CH₃ and C₆H₅) have been synthesized and characterized by IR, ¹H NMR, UV‐visible, electrospray ionization mass spectrometry and elemental analysis. The single‐crystal structures of 1 and 3 have been determined. The molecular orbitals and electronic absorption spectra of the compounds have been calculated using the DFT and TDDFT methods. The in vitro antiproliferative activities of these complexes have been evaluated against four human cancer cell lines (CNE, H292, SKBR3 and Hey1‐B), and 3 is proved to be the most efficient inhibitor, with IC₅₀ values of 20, 31, 10 and 34 μm , respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

Three‐dimensional Hemidirected Mixed‐ligand Lead(II) Coordination Polymer, [Pb2(bpa)2(SCN)3(NO3)]n (bpa = 1,2‐di(4‐pyridyl)ethane)

A new 3D hemidirected mixed‐ligand lead(II) coordination polymer with the ligand 1,2‐di(4‐pyridyl)ethane bpa) and the two metal coordinated anions nitrate and thiocyanate, [Pb₂(bpa)₂(SCN)₃(NO₃)]_n ( 1 ), has been synthesized and characterized by CHN elemental analysis, IR‐, ¹H‐ and ¹³C NMR spectroscopy. The single crystal X‐ray data of compound 1 show that the complex is a three‐dimensional coordination polymer with two different Pb atoms with stereoactive electron lone pairs and six‐ and five‐coordinate hemidirected geometries, respectively.