Weak Pb Research Articles

Synthesis and Characterization of the New Nano Flowers Lead(II) Coordination Polymer with Hemidirected Coordination Sphere

Nano flowers of a new polymeric lead(II) complex containing the azide anions, [Pb(baea)(N3)·(N3)]n (“baea” is the abbreviation of bis(2-aminoethyl)amine), has been synthesized by a sonochemical method. The new nano-structure was characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, elemental analyses, and IR spectroscopy. Single crystalline material was obtained using a heat gradient applied to a solution of the reagents. Single-crystal X-ray diffraction analyses show that the coordination number for PbII ions is five, PbN5 and hold hemidirected coordination geometry. To the best of our knowledge, the 1D coordination polymer interact with each other via supramolecular and weak Pb···N interactions to create 2D supramolecular frameworks.

Pb2(AsO2OH)Cl2, a new phase from the Lavrion ancient slags, Greece: occurrence and characterization

AbstractTransparent prismatic crystals of Pb2(AsO2OH)Cl2were collected in black metallurgical slag on the coast in the Punta Zeza area, 3 km south of the town of Lavrion, Greece. Analyses by energy-dispersive X-ray spectrometry (EDS) provided the following chemical composition: PbO 73.04, As2O315.97, Cl 11.42, O=Cl –2.58, total 97.85 wt.%. The empirical formula calculated on the basis of As = 1 is HxPb2.03(AsO3)1.00Cl1.995(x = 0.96). The infrared spectrum of Pb2(AsO2OH)Cl2has characteristic AsO33–bands at 707 and 594 cm–1, O–H stretching vibrations at 3310 and 2900 cm–1and a band at 1107 cm–1which is assigned to As–O–H bending vibrations. The structure, which is monoclinic P21/m, a = 6.4235(8), b = 5.5399(7), c = 9.321(1) Å, β = 90.767(2)°, V = 331.67(7) Å3, R1= 0.035, is identical to that of synthetic Pb2(AsO2OH)Cl2and contains two symmetrically unique Pb sites and one As site. The crystal structure is based on [Pb2AsO2OH]2+double chains interconnected via weak Pb–Cl bonds to produce a three-dimensional framework which is closely related to that of Pb oxysalt minerals containing [O2Pb3]2+chains of oxocentred [OPb4]6+tetrahedra including mendipite, damaraite, rickturnerite and plumboselite.

A lead(II) coordination polymer containing 2-carboxycinnamic acid and 1,10-phenanthroline and its 3-D supramolecular network

The coordination polymer {[Pb(cca)(phen)]H2O} n (H2cca = 2-carboxycinnamic acid and phen = 1,10-phenanthroline) was synthesized by hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. The complex possesses a 1-D chain structure composed of infinite Pb-cca-Pb linkages, in which the [PbO4N2] subunits are linked by bridging cca in bis(chelating-bridging) coordination mode. The coordination around the lead(II) is hemi-directed and weak Pb···O interactions are observed that result in a double-chain structure. The chains are combined to generate a 3-D supramolecular structure through interchain C–H···π, C–H···O, and π···π stacking interactions. Fluorescence of the complex originates from π*–π transitions of the ligand.

Syntheses, crystal structures, and luminescence of two main-group metal complexes based on 3,4-pyrazoledicarboxylic acid

Two new metal complexes, [Pb(H2pdc)2(H2O)] · 2H2O (1) and [Sr2(H2pdc)4(H2O)8] · 2H2O (2) (H3pdc = 3,4-pyrazoledicarboxylic acid), have been synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. In 1, the geometry of Pb(II) is hemidirected and the 6s2 lone electron pair on Pb(II) is stereochemically active, resulting in the formation of a secondary Pb ··· O bond. The weak Pb ··· O interactions, π–π stacking, and hydrogen-bonding interactions construct 1 into a 3-D framework with 1-D channels. Complex 2 is a dinuclear structure, which is further assembled to a 3-D supramolecular network through intermolecular hydrogen bonds and π–π stacking. Three coordination modes of 3,4-pyrazoledicarboxylic acid were observed. The thermal and photoluminescent properties of 1 and 2 in the solid state have also been investigated.

Crystal and molecular structures of two triphenyllead xanthates, Ph3Pb(S2COR), R = Me and i-Pr, featuring weak intramolecular Pb … O interactions

Abstract The crystal structure of Ph3Pb(S2COMe) (1) features a tetrahedrally coordinated lead centre existing within a distorted tetrahedral geometry defined by three ipso-carbon atoms and a sulphur atom derived from a monodentate xanthate ligand. The xanthate ligand is orientated to place the oxygen atom in close proximity to the lead atom rather than the formally thione-sulphur atom. The structure of Ph3Pb(S2CO-i-Pr) (2) comprises three independent molecules that differ from each other only in the relative orientations of the lead-bound phenyl groups, the distorted tetrahedral coordination geometries and orientation of the xanthate ligand resembles that observed in (1). Globally, the crystal structures are similar in that they both comprise supramolecular layers of molecules self-assembled through C—H … π(aryl) contacts. Crystal data for (1): monoclinic, Cc, a = 17.614(4), b = 8.4270(18), c = 15.392(4) Å, β = 120.351(3)°, V = 1971.5(8) Å3, Z = 4, R = 0.028. Crystal data for (2): triclinic, P-1, a = 10.0922(11), b = 12.1182(12), c = 26.815(3) Å, α = 91.741(9), β = 96.406(9), γ = 96.768(9)°, V = 3233.1(6) Å3, Z = 6, R = 0.037.

μ-4,4′-Bipyridine-κ2N:N′-bis[bis(2-chlorobenzoato-κ2O,O′)lead(II)

In the title dinuclear complex, [Pb2(C7H4ClO2)4(C10H8N2)], the PbII atom is five-coordinated by four carboxyl­ate O atoms from two 2-chloro­benzoate ligands and one N atom from a bridging 4,4′-bipyridine (4,4′-bpy) ligand, displaying a hemi-directed coordination. The 4,4′-bpy ligand has an inversion center at the mid-point of the central C—C bond. The empty side of the metal ion is capped by two carboxyl­ate O atoms from a neighboring mol­ecule, with weak Pb⋯O contacts [Pb⋯O = 3.069 (2) and 3.071 (3) Å]. The crystal structure is stabilized by C—H⋯O hydrogen bonds and π–π stacking inter­actions between the benzene and pyridine rings [centroid–centroid distance = 3.749 (3) Å].

Synthesis, Characterization, and Properties of Four Metal Complexes with Mulitdentate N‐Acyl‐Salicylhydrazide Ligands

AbstractThe reactions of the new nitrilotriacetic acid N′,N′,N′‐tri(salicyloyl)trihydrazide (Ntash) with the corresponding metal salts gave four new complexes [Pb4(bshz)2]·2DMF (1), [Co2(bshz)(C5H5N)6]·2ClO4·(C5H5N)·2H2O (2), [Cu3(fshz)2(C5H5N)2] (3), and [Zn3(fshz)2(C5H5N)3]n·2DMF (4), in which two multidentate ligands, namely N,N′‐disalicyloylhydrazine (H4bshz) and N‐formylsalicylhydrazide (H3fshz) were generated in situ from Ntash. The structures of these complexes were determined by single‐crystal X‐ray diffraction analysis. Complex 1 presents a novel tetranuclear lead(II) cluster structure with the four lead(II) cations in “hemidirected” coordination spheres. The neighboring tetranuclear clusters of 1 are connected by DMF molecules through weak Pb–O bonds, forming one‐dimensional ribbons. Complexes 2 and 3 show dinuclear and linear trinuclear structures with the corresponding CoIII and CuII ions in distorted octahedral and square‐planar coordination environments, respectively. Complex 4 exhibits a one‐dimensional zigzag chain structure. The magnetic properties of 3 and the photoluminescent properties of 4 were also investigated.

Two lead(II) 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate complexes exhibiting different topologies and fluorescent properties

The reactions of PbCl 2 with 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid (H 3iso) gave two complexes [Pb(H 2iso) 2(H 2O)] n ( 1) and [Pb(Hiso)(H 2O)] n ( 2), which were characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, powder X-ray diffraction and single crystal X-ray diffraction analysis. The two complexes display different topologies. 1 shows a three-dimensional framework with the Schläfli symbol (4.8 5)(4.8 2) no matter if the weak Pb–O bonds are included or not. However, 2 presents a 3,3-connected two-dimensional sheet with the Schläfli symbol (4.8 2)(4.8 2) based on the calculation of only the normal Pb–O bonds and a 5,5-connected 3D network with the Schläfli symbol (4 15.6 4)(4 4.6 8.8 2) when the weak Pb–O bonds are also included. The fluorescent studies reveal an emission attributed to intraligand emission for 1 and an emission assigned to LMCT for 2.

Catena-Poly[lead(II)-bis-(μ-2-amino-1,3-benzothia-zole-6-carboxyl-ato)

The title complex, [Pb(C8H5N2O2S)2]n, consists of one PbII ion located on a crystallographic twofold axis and two symmetry-related 2-amino-1,3-benzothia­zole-6-carboxyl­ate (ABTC) ligands. The central PbII ion has a (4 + 2) coordination by four O atoms of the two ABTC ligands and two weaker Pb—S bonding inter­actions (Pb—S secondary bonds) from S atoms of other two neighbouring ABTC ligands. These bonds link the metal ions into zigzag chains along the c axis, which, in turn, aggregate through π–π inter­actions [centroid–centroid distance = 3.7436 Å] between ABTC rings and N—H⋯O and N—H⋯N hydrogen bonds.

Two lead coordination polymers with nitrilotriacetic acid and oxydiacetic acid: synthesis, characterization, and crystal structure

Two lead coordination compounds [Pb2(nta)]NO3 (1) and [Pb(oda)] (2) have been synthesized by slow evaporation or hydrothermal conditions using nitrilotriacetic acid (nta) and 2,2′-oxydiacetic acid (oda) as ligands, respectively. Their structures were determined by single-crystal X-ray diffraction and further characterized by X-ray powder diffraction, infrared absorption spectrum, and thermogravimetric analysis. Compound 1 is a 2-D honeycomb-like layer structure with (6,3) topology. When the bonding limit of Pb–O extends from 2.76 to 2.90 Å, potential weak Pb–O bonds can be found in 1, and the 2-D layer structure can be further linked to generate a 3-D 4-connected supramolecular sra net with the (42.63.8) Schläfli symbol. Compound 2 contains a 1-D infinite Pb–O chain which is connected through µ3-, µ4-, and µ5-coordination modes of oda to form a new 3-D structure.

Solution and solid-state photoluminescence of dinuclear Pb(II) dicarboxylate compound with 2,6-bis(benzimidazolyl)pyridine: The lone-pair stereochemistry and its effect on supramolecular interaction

[Pb2(boa)(Hbbp)2] has been synthesized by treating 4-carboxylphenoxyacetic (H2boa) and 2,6-bis(benzimidazolyl)pyridine (H2bbp) with metal salts under hydrothermal conditions. Adjacent metal centers forms dinuclear metal complex through carboxylato groups as building blocks. The arrangement of the half deprotonated H2bbp ligand and carboxylate groups exhibits a coordination gap around the Pb(II) ion, occupied possibly by a stereoactive lone pair of electrons on Pb(II), with the coordination environment around the lead atoms is hemidirected. This system is a particularly clear example that coordination sphere of a unique dinuclear Pb(II) compound was controlled by lone pair activity, weak Pb···O interactions, π–π stacking and the hydrogen bonds. The above weak interactions influence differently strong red-shifted effect about the solution and solid-state photoluminescence of the compound, compared to the free ligand.

Comparisons of PE and PB between SDB and Vanke A

Due to real estate and financial industry respectively characterized by strong and weak periodicity, this articleaiming to investigate which kind of cyclical industry in the listed companies will Price/Earnings (PE) andPrice/Book value (PB) be more suitable for evaluating selects the data of Shenzhen Development Bank (SDB)and Vanke A from Feb. 28 1991 to June 30 2009, uses mean-variance comparison method and analyzes theirsPE and PB. The results are that PE is more suitable for the evaluation of SDB and PB is more suitable for theevaluation of Vanke A. It shows that to some extent PE is more suitable for the evaluation of weak cyclicalindustry and PB is more suitable for the evaluation of strong cyclical industry.

Thermal transformation of 1D-Pb(en) 2Cl 2 to 3D-PbCl 2via 2D-Pb(en)Cl 2 and their substantial modification of the coordination environment on Pb(II)

The solvothermal synthesis and crystal structures of two new lead(II) compounds, bis(ethylenediamine)lead(II) chloride, Pb(en) 2Cl 2 1 and mono(ethylenediamine)lead(II) chloride, Pb(en)Cl 2 2, are reported. A detailed comparison of the two structures is given. In 1, the Pb(II) center is coordinated by two chlorine atoms and four nitrogen atoms from three en ligands, which act as either chelating or bridging ligands, allowing links to other Pb(II) centers. This creates an infinite linear chain of Pb(en) 2Cl 2. In 2, the Pb(II) center is chelated by one en ligand and is coordinated by six chlorine atoms, including two unusually weak Pb–Cl bonds (>3.5 Å) connected through μ 2- and μ 4-Cl to build a neutral layer of Pb(en)Cl 2 units. Complex 1 contains a hemidirected Pb(II), while complex 2 has a (pseudo-)hemidirected Pb(II). TGA and high-temperature controlled powder-XRD studies show that compound 1 decomposes to compound 2 near 150 °C, and finally to PbCl 2 above 320 °C.

Structure and Characterization of a Novel 3D Lead Phosphonate Metal - Organic Framework with Cationic Layer Based on Weak Pb - O(N) Contact

A novel lead-phosphonate, [Pb2(HL)]·(NO3)·2(H2O) 1 (H4L = H2O3PCH2N(C4H8)NCH2PO3H2 N,N′-piperazinebis(methylenephosphonic acid), so HL = O3PCH2NH(C4H8)NCH2PO3), has been hydrothermally synthesized and characterized by elemental analysis, IR, TG-DTA, and X-ray single-crystal diffraction. Compound 1 possesses a 2D cationic layer structure built from inorganic chains with three types of eight-membered rings arranged in an ABAC manner. In 1, both crystallographic distinct Pb(II) ions adopt three-coordination geometry, and a counter anion NO3 – and two lattice water molecules occupy the voids between 2D layers. After the removal of solvent, the size of tunnel formed by 2D layers is 137.9 Å3 per unit cell, comprising 17.0% of the crystal volume based on the crystal structure. When the bond length of Pb–O(N) extended to 3.10 Å, a 3D metal–organic framework was constructed via long Pb–O(N) contacts, simultaneously accompanied by the hemi- to holo-directed transition in coordination geometry of Pb(II). Except for the long Pb–O contacts, a 3D supramolecular network is also formed by hydrogen bonds (N–H···O, O–H···O, and C–H···O), van der Waals forces as well as electrostatic interactions. The result of fluorescence measurements indicates that 1 shows a fluorescent emission band at 465 nm (λexcitation = 215 nm).

μ-Adipato-κ2O1:O4-bis{[2,6-bis(1H-benzimidazol-2-yl-κN3)pyridine-κN](nitrato-κO)lead(II)}

The dinuclear title compound, [Pb2(C6H8O4)(NO3)2(C19H13N5)2], lies with the mid-point of the butyl chain of the bridging adipate unit on a center of inversion. The PbII ion is covalently bonded to the nitrate anion and is bonded to a carboxyl­ate group of the adipate unit by another covalent bond. The N-heterocycle functions in a chelating tridentate mode. The metal atom exists in a Ψ-octa­hedral coordination environment. When weaker Pb⋯O inter­actions are also considered, the geometry is a Ψ-tricapped trigonal prism in which the lone-pair electrons occupy one face of the trigonal prism. Adjacent mol­ecules are linked into a layer structure by N—H⋯O hydrogen bonds.

Synthesis, crystal structure and characterization of lead(II) coordination polymers with tetrafluorosuccinate/hexafluoroglutarate

Abstract Two complexes, [Pb(TFSA)(phen)]n (1) and [Pb(HFGA)(phen)]n (2) (TFSA = tetrafluorosuccinate, HFGA = hexafluoroglutarate, and phen = 1,10-phenanthroline) have been synthesized and structurally characterized by single-crystal X-ray diffraction. The 1 shows that the 2-D structure with six normal Pb–ligand bonds and one weak Pb⋯O bond, and then is further connected by C–H⋯O and C–H⋯F hydrogen bonds, forming a 3-D network. The 2 has 1-D structure with four normal Pb–ligand bonds that further produces a 3-D network by C–H⋯O, C–H⋯F hydrogen bonds, and weak Pb⋯O bonds. The two complexes display high thermal stability and luminescent properties.

Catena-Poly[[(1,10-phenanthroline-5,6-dione-κ2N,N′)lead(II)]-μ-terephthalato-κ2O1:O4

The PbII atom in the polymeric title compound, [Pb(C8H4O4)(C12H6N2O2)]n, is chelated by the N-heterocycle, and adjacent atoms are bridged by rigid terephthalate dianions into a linear chain. The PbII atom is stereochemically active in a ψ-square-pyramidal coordination geometry in which the lone-pair electrons occupy a basal site. When three other weaker Pb⋯O inter­actions are considered, the geometry is a ψ-dodeca­hedron.

Preparation of calcium plumbate via different route

Calcium plumbate Ca2PbO4 was prepared by sol–gel methods (Pechini complex route with two varieties and water soluble polymer method) and by solid state reaction. The sol–gel prepared samples contained calcium plumbate as the only one phase as early as after 2 h annealing at 800 °C. Phase composition was detected by XRD measurement and by Raman spectroscopy. The next annealing at 800 °C for 24 h induced weak Pb losses displayed by present CaO (according to phase equilibrium) and confirmed by XRF measurement. The Pb losses were smaller for the sol–gel prepared samples probably due to earlier formation of Ca2PbO4. Microstructure and grain size were also established. Sol–gel prepared samples had regularly distributed grains with a small distribution interval with median value in order of 1 μm. Differences in microstructure of solid state and sol–gel samples are presented on SEM micrographs.

Structural and Thermophysical Properties of (PbO)0.5(SiO2)0.5Glasses: Effect of SnO2Incorporation

119Sn and 29Si solid-state nuclear magnetic resonance studies on lead silicate glasses containing different amounts of SnO2 confirmed that tin exists in the glass as distorted SnO6 polyhedra and there is no direct interaction between tin and silicon structural units. Transmission electron microscopic studies have established that tin structural units are uniformly distributed in the glass. Significant changes in the values of glass transition temperature, microhardness, and thermal expansion coefficient with SnO2 incorporation into the glass have been attributed to the increased rigidity of the glass network brought about by the replacement of weaker Pb–O linkages with stronger Sn–O linkages.

Lead(II) complexes of proline

Three new proline (pro) lead(II) complexes were synthesized and characterized by elemental analyses, IR, 1H NMR, and 13C NMR spectroscopy. Single crystal X-ray structural analysis of [Pb(pro)(H2O)] n shows the complex to be a novel 1D chain polymer as a result of water bridging. Coordination number of Pb(II) is six, with a ‘stereo-chemically active’ electron lone pair, and the coordination sphere is hemidirected. The chains interact with each other via weak Pb ··· O intractions and hydrogen bonding to create a 2D framework.