Synthesis, characterization and crystal structure of cis,mer-[ReH(CO)2{PPh(OMe)2}3]

The dicarbonylhydride complex cis,mer-[ReH(CO)₂{PPh(OMe)₂}₃] (1) was serendipitously obtained when, in an attempt to replace a CO ligand by the phosphonite ligand PPh(OMe)₂ in [ReH(CO)₃(L)] (L = PPh₂OCH₂CH₂OPPh₂), this complex was treated with PPh(OMe)₂ under UV irradiation. The complex 1 was characterized by IR, ¹H and ³¹P{¹H} NMR spectroscopy and by crystal structure determination. The spectroscopic features are consequent with the cis,mer configuration showed by the X-ray crystallographic analysis of the complex. The environment of the metal centre is a distorted octahedron.     

Poly(o-toluidine) as the matrix for incorporation of palladium species from PdCl2 aqueous solutions

Reactivity of poly(o-toluidine) in the emeraldine base form (POT) and protonated with HCl (POT/HCl) in PdCl₂ aqueous solutions of various HCl concentrations has been studied. Using elemental analysis, FTIR, UV–Vis, XPS and EXAFS spectroscopies as well as XRD and SEM it has been established that POT/HCl is more reactive than POT. The course of reactions is influenced by the type of the PdCl₂ solution. Thus, protonation of POT with incorporation of palladium (II) chloro–and/or aquachloro–and/or chlorohydroxycomplexes counterions is the main process occurring in the PdCl₂ solutions of higher HCl concentration. A redox reaction resulting in the oxidation of the polymer chain with simultaneous formation of metallic palladium takes place in the PdCl₂ solution of lower HCl concentration. POT/HCl shows enhanced reducing properties with respect to POT. Lowering of the protonation level (i.e. some deprotonation) of POT/HCl has been also observed. Coordination of palladium (II) ions by nitrogen atoms of the polymer chain can be also postulated.     

Synthesis, structure and photoluminescence of a novel palladium(I) compound: [Pd3(μ3-Cl)2(dppp)3][Pd2(μ2-Cl)3(PPh3)2](PPh3)2

Pd(PPh₃)₂Cl₂ reacts with PdCl₂ and 1,3-bis(diphenylphosphine)propane (dppp) in ethanol–DMF–pyridine mixed solvent to yield a novel palladium(I) compound [Pd₃(μ₃-Cl)₂(dppp)₃][Pd₂(μ₂-Cl)₃(PPh₃)₂](PPh₃)₂. It features an isolated structure based on [Pd₃(μ₃-Cl)₂(dppp)₃]⁺ cations having triangulo-palladium clusters and [Pd₂(μ₂-Cl)₃(PPh₃)₂]⁻ anions in which the coordination environment of palladium is an unusual tetrahedral geometry. Its photoluminescence is measured.     

Direct synthesis and characterization of novel homo- and heterometallic mixed-ligand tetrazolate complexes, Cu(en)(tz)2 and Cu(en)2Zn(tz)4 [en = ethylenediamine, tz = tetrazolate]

For the first time, tetrazolate complexes have been prepared by direct synthesis. Two novel homo- and heterometallic mixed-ligand complexes, Cu(en)(tz)₂ and Cu(en)₂Zn(tz)₄, have been synthesized using tetrazole (Htz), ethylenediamine (en), metallic copper and zinc oxide as starting materials. Both tetrazolates were characterized by single-crystal X-ray diffraction, IR spectroscopy and thermal analysis. The complexes present 1D coordination polymers, with tetrazolate anions acting as both monodentate and bridging ligands.     

Diplatinum(III) [Cl2(μ2-amidinate)4] compound derived from air oxidation of mononuclear cis-[Pt(NH3)2(amidine-κ)2] complex

The dinuclear platinum(III) complex [Pt₂Cl₂{μ₂-N(H)C(Et)N(H)}₄] (2) has been prepared by heating cis-[Pt(NH₃)₂{NHC(NH₂)Et}₂](Cl)₂ (cis-1) under aeration conditions in an EtOH/H₂O mixture at 70 °C for 2 d and it was characterized by elemental analyses (C, H, N), ESI⁺-MS, IR, ¹H and ¹³C NMR spectroscopies and also by X-ray diffraction. Complex 2 represents the second Pt^III dimer stabilized by the amidinate ligand ever known and it has a lantern-type structure with four amidinate ligands bridging two Pt^III centers with Pt–Pt distance of 2.4809(2) Å.     

Polylinked adamantanoid structure of Cd(SePh)2

The solid state structure of Cd(SePh)₂ is built up of adamantanoid cages linked through four vertices to form a three-dimensional nonmolecular polyadamantanoid or superdiamondoid network, ³_∝[(μ-SePh)₆Cd₄(μ-SePh)_4/2].     

Synthesis, characterization and crystal structure of a novel co-ordination polymer [Co(BTB)2(NCS)2]n

A novel polymeric cobalt(II) complex with flexible ligand, [Co(BTB)₂(NCS)₂]_n 1 {BTB = 1,4-bis(1,2,4-triazol-1-yl)butane} has been prepared and structurally characterized by single-crystal X-ray diffraction as well as with elemental analysis, infrared spectroscopy and thermogravimetric analysis. The complex 1 consists of two discrete constituents, A and B, with the same chemical formula [Co(BTB)₂(NCS)₂] but different connecting mode. The six-co-ordination of Co²⁺ in A and B is in a distorted octahedral environment formed by four nitrogen atoms of the triazoles and two nitrogen atoms from two trans thiocyanato ligands. The structures of A and B demonstrate a one-dimensional neutral looped chain through two BTB-bridges and a two-dimensional network in which four BTB bridge four Co(II) atoms, respectively. A and B interpenetrate in an inclined fashion. The flexible BTB ligand exhibits three different configurations in 1.     

Reduction of nitroaromatics with poly(vinylpyridine) complexes of palladium(II) and platinum(II)

Palladium(II) and platinum(II) anchored to 2- and 4-vinylpyridine polymers of different molecular weights were used for the dihydrogen reduction of various nitroaromatics and benzaldehyde in ethanol at 50°C. Palladium(II) complexes were far more effective than their platinum(II) analogues and the activity decreased with increasing molecular weights of the polymers. The nitroaromatics were selectively and almost completely reduced to the corresponding anilines. During reduction, the orange palladium(II) complexes changed to voluminous green precipitates, which could be used repeatedly and preserved for a long time without any loss of activity. A rate equation of the type: rate = K[Cat] [H₂] has been derived and a reduction mechanism has been proposed on the basis of experimental results and kinetic data.     

Self-assembled chloro-bridged metallo-prismatic cations of the general formula [M6(η-C5Me5)6(μ3-tpt)2(μ-Cl)6] (M = Rh, Ir; tpt = 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine)

Two cationic pentamethylcyclopentadienyl metal-based hexanuclear complexes with trigonal prismatic architecture have been synthesised through a two-step strategy. The dinuclear complexes [M(η⁵- C₅Me₅)(μ-Cl)Cl]₂ (M = rhodium and iridium) react with 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (tpt) in dichloromethane to give the trinuclear complexes [Rh₃(η⁵-C₅Me₅)₃(μ₃-tpt)Cl₆] (1) and [Ir₃(η⁵-C₅Me₅)₃(μ₃-tpt)Cl₆] (2), respectively. Addition of silver triflate to 1 and 2 in dichloromethane connects two identical triangular panels to form the hexanuclear metallo-prismatic cations [Rh₆(η⁵-C₅Me₅)₆(μ₃-tpt)₂(μ-Cl)₆]⁶⁺ (3) and [Ir₆(η⁵-C₅Me₅)₆(μ₃-tpt)₂(μ-Cl)₆]⁶⁺ (4), respectively. Cations 3 and 4 have been isolated as their triflate salts and characterised by ¹H NMR, IR and UV/visible spectroscopy.     

Electronic transition,ferroelectric and thermoelectric properties of bismuth pyrostannate Bi2(Sn0.85Cr0.15)2O7

The ferroelectric properties of bismuth pyrostannate Bi₂(Sn_0.85Cr_0.15)₂O₇ in the high-temperature region are established. The linear thermal expansion coefficient, electrical resistance, impedance, I?V characteristics, capacitance, loss-angle tangent, charge, and thermopower of the investigated material are measured in the temperature range of 300?700 K at frequencies of 10²?10⁶ Hz. Anomalies of the thermal expansion coefficient and hodograph spectrum variation in the region of polymorphic phase transitions are observed. The high resistance and change of the hopping conductivity for the tunnel-emission are found. The hysteresis in the electric field dependence of polarization is established. The change in the thermopower sign with temperature is revealed. The obtained experimental data are explained in the framework of the model of migration polarization by charged chromium ions.     

Polymerization of 1,3-butadiene with VO(P204)2 and VO(P507)2 activated by alkylaluminum

The oxovanadium phosphonates (VO(P₂₀₄)₂ and VO(P₅₀₇)₂) activated by various alkylaluminums (AlR₃, R = Et, i-Bu, n-Oct; HAlR₂, R = Et, i-Bu) were examined in butadiene (Bd) polymerization. Both VO(P₂₀₄)₂ and VO(P₅₀₇)₂ showed higher activity than those of classical vanadium-based catalysts (e.g. VOCl₃, V(acac)₃). Among the examined catalysts, the VO(P₂₀₄)₂/Al(Oct)₃ system (I) revealed the highest catalytic activity, giving the poly(Bd) bearing M_n of 3.76 × 10⁴ g/mol, and M_w/M_n ratio of 2.9, when the [Al]/[V] molar ratio was 4.0 at 40 °C. The polymerization rate for I is of the first order with respect to the concentration of monomer. High thermal stability of I was found, since a fairly good catalytic activity was achieved even at 70 °C (polymer yield > 33%); the M_n value and M_w/M_n ratio were independent of polymerization temperature in the range of 40-70 °C. By IR and DSC, the poly(Bd)s obtained had high 1,2-unit content (>65%) with atactic configuration. The 1,2-unit content of the polymers obtained by I was nearly unchanged, regardless of variation of reaction conditions, i.e. [Al]/[V], ageing time, and reaction temperature, indicating the high stability of stereospecificity of the active sites.     

Synthesis and H2 uptake of Cu2(OH)3Cl, Cu(OH)2 and CuO nanocrystal aggregate

Monodispersed Cu₂(OH)₃Cl nanoplatelets, Cu(OH)₂ nanowires, CuO nanoparticles and nanoribbons with a spherical morphology were synthesized using hydrothermal and heat-treatment reactions, and their H₂ storage characteristics were examined. The Cu₂(OH)₃Cl nanoplatelets particles formed immediately after mixing the reactant, which subsequently formed larger uniform spherical particles in the submicron range. This procedure highlights a practical strategy for producing spherical Cu(OH)₂ and CuO materials consisting of monodispersed nanocrystals. The spherical aggregates of Cu₂(OH)₃Cl nanoplatelets heat-treated at 473 K could reversibly store up to 2.35 wt.% H₂ at 38 bar and 293 K.     

The RuCl3(dppb)H2O complex: A new metal-assisted oxidative dehydrogenation of the o-phenylenediamine ligand

The trans-[RuCl₂(dppb)(bqdi)] and trans-[RuCl₂(dppb)(opda)] complexes (dppb = 1,4-bis(diphenylphosphine)butane, bqdi = o-benzoquinonediimine, and opda = o-phenylenediamine) were synthesized from the reaction of the mer-[RuCl₃(dppb)(H₂O)] aqua-complex with the opda ligand. The X-ray structural and electrochemical characterizations of the isolated compounds showed that this aqua-complex induces the oxidative dehydrogenation of the amine species (opda) to the imine form (bqdi) of the o-phenylene ligand during the synthetic procedure. In the presence of oxygen, the ³¹P{¹H} NMR experiments confirmed that the trans-[RuCl₂(dppb)(bqdi)] complex is the only product formed.     

A hemidirected 1-D coordination polymer [Pb2(H2O)2(HBTC)2] · 3H2O extended in holodirected 3-D by weak Pb–O interactions

A new complex, [Pb₂(H₂O)₂(HBTC)₂] · 3H₂O (H₃BTC = 1,3,5-Benzenetricarboxylic acid) (1), has been synthesized under hydrothermal condition. The single-crystal analysis shows that 1 consists of 1-D double-chains with Pb(II) six-coordinated by three H₃BTC and one H₂O molecule with the Pb–O bond distances in the range of 2.56–2.76 Å. When the Pb–O bonding limit extends from 2.76 to 2.90 Å, the potential weak bonds of Pb–O can be found and the coordination number of Pb will increase from six to nine. As a result, the coordination geometry of Pb(II) transforms from hemidirected to holodirected and an infinite 3-D framework is obtained by the connection of the double-chains. The IR spectrum and the TGA–DTA curve of 1 are also reported in this paper.     

Influence of metal coordination on conductivity behavior in poly(butadiene-acrylonitrile)-CoCl2 system

The metal complex formation and the electrical properties of amorphous solid polymer electrolytes, based on poly(butadiene-acrylonitrile) copolymer (PBAN) and CoCl₂, have been studied over the homogeneity region of the system limited by the CoCl₂ concentration of 1.89 mol kg⁻¹. It has been found that ionic conductivity is carried out by the unipolar anion transfer at lower CoCl₂ concentrations (up to 0.10 mol kg⁻¹). As the CoCl₂ concentration increases, electronic conductivity appears in addition to ionic conductivity, and the former becomes dominant, starting from 0.38 mol kg⁻¹. It has been shown that the nature of charge carriers is determined by the composition of metal complexes formed by CoCl₂ and the macromolecular solvent PBAN. At lower concentrations, the [Co₂L₂Cl₄]⁰ dimers are the predominant species (L being macromolecule side groups CN), and their dissociation is followed by the formation of mobile Cl⁻ anions and immobile binuclear [Co₂Cl₃]⁺ complexes. As CoCl₂ concentration increases, polynuclear [Co_nL₂Cl_2n]⁰ (n > 2) complexes appear (L being CN and CC groups of PBAN). Specific features of chemical bonds in π-complexes of transition metals result in the appearance of electronic charge carriers. The abrupt increase in conductivity observed at the highest CoCl₂ concentration is connected with the formation of a percolation network of polynuclear [Co_nL₂Cl_2n]⁰ complexes.     

Phosphate triester hydrolysis promoted by S3–zinc(II) complexes with a bridged hydroxide: The crystal structure of TtiZn–OP(O)(OC6H4-p-NO2)2, Tti = hydrotris(N-xylyl-2-thioimidazolyl)borate

The bridged μ-hydroxo dinuclear four-co-ordinated zinc(II) complex 2, derived from hydrotris(N-xylyl-2-thioimidazolyl)borate cleaves the P–O bond in tris(p-nitrophenyl)phosphate to form a mixture of a monomeric phosphate diester complex 3 and phenoxo complex 4.     

Metal-organic framework Cu3 (BTC)2(H2O)3 catalyzed Aldol synthesis of pyrimidine-chalcone hybrids

A typical metal organic framework, [Cu₃ (BTC)₂(H₂O)₃, BTC = 1,3,5-benzene tricarboxylate] has been used for the synthesis of pyrimidine-chalcones. We have explored a green synthesis of pyrimidine chalcones under Cu₃(BTC)₂ catalysis by Aldol condensation. Easy isolation of product, excellent yield, and recyclable catalyst makes this reaction eco-friendly. The technology was demonstrated to be applicable to the synthesis of a host of chemical hybrids.     

Kinetics of Polyurethane Formation in Polymerization Reactions Using the Organometallic Diol (η5-C5H4CH2CH2OH)2Mo2(CO)6

Summary The kinetics of the dibutyltin diacetate (DBTA) – catalyzed polymerization reactions of (η⁵-C₅H₄CH₂CH₂OH)₂Mo₂(CO)₆ with Hypol 2000 (an isocyanate-terminated polyether prepolymer) and with 1,4-butanediol were studied, as were the kinetics of a copolymerization involving (η⁵-C₅H₄CH₂CH₂OH)₂Mo₂(CO)₆ and PEG-1000 (a poly(ethylene glycol)) with Hypol 2000. The purpose was to determine if (η⁵-C₅H₄CH₂CH₂OH)₂Mo₂(CO)₆ appreciably affected the overall rate of the polymerization reaction and if it changed the mechanism of the reaction. The kinetics were analyzed with a fitting program, which allowed extraction of the rate constants for the individual elementary steps in the mechanism. The results showed that (η⁵-C₅H₄CH₂CH₂OH)₂Mo₂(CO)₆ does not significantly alter the timescale of the reaction and that the same reaction mechanism is likely used as with the 1,4-butanediol and PEG-1000. There are some differences in the rate constants of the elementary steps, but these differences can be attributed to the increased steric crowding caused by the bulkier (η⁵-C₅H₄CH₂CH₂OH)₂Mo₂(CO)₆ diol. The effect of the (η⁵-C₅H₄CH₂CH₂OH)₂Mo₂(CO)₆ on the polymers’ physical properties was also investigated. As is the case with other segmented polyurethanes, the hydrogen bonding index (HBI) and the relative amount of soft segments of the (η⁵-C₅H₄CH₂CH₂OH)₂Mo₂(CO)₆-containing polyurethane correlate in a general way with the physical properties of the polymer.