[Re(NBH2SBH3)(Me2PhP)(Et2dtc)]2 — a novel rhenium dimer with the unusual bridging (NBH2SBH3)4− ligand

The title compound is formed during the reaction of [ReN(Me₂PhP)(Et₂dtc)₂] (Me₂PhP=dimethylphenylphosphine, Et₂dtc⁻=diethyldithiocarbamate) with excess BH₃ in tetrahydrofurane. Two Re^V atoms are linked by two (NBH₂SBH₃)⁴⁻ units which act as three-dentate ligands via N, S and H forming an eight-membered metallacycle with additional coordination of an hydrido H atom trans to the nitrogen atom. The ReN multiple bond length is 1.70(1) Å which is only slightly longer than in the starting compound [ReN(Me₂PhP)(Et₂dtc)₂] (1.666(6) Å).     

An unusual intramolecular metallalactone formation from coordinated alkoxide and CO: molecular structure of Au3Ru3{μ3-η1:η1:η1,η2-CCHCPh2OC(O)}(CO)8(PPh3)3

Sequential treatment of Ru₃(μ-H){μ₃-C₂CPh₂(OH)}(CO)₉ with K[BHBu^s₃] and AuCl(PPh₃) afforded Au₃Ru₃{μ₃-η¹:η¹:η¹,η²-CCHCPh₂OC(O)}(CO)₈(PPh₃)₃, formed by intramolecular attack of alkoxide on an adjacent CO ligand, and characterised by a single-crystal X-ray study.     

N-Aryl stilbazolium dyes as sensitizers for solar cells

Eight new N-arylstilbazolium chromophores with electron donating -NR₂ (R = Me or Ph) substituents have been synthesized via Knoevenagel condensations and isolated as their PF₆⁻ salts. These compounds have been characterized by using various techniques including ¹H NMR and IR spectroscopies and electrospray mass spectrometry. UV-vis absorption spectra recorded in acetonitrile are dominated by intense, low energy π → π* intramolecular charge-transfer (ICT) bands, and replacing Me with Ph increases the ICT energies. Cyclic voltammetric studies show irreversible reduction processes, together with oxidation waves that are irreversible for R = Me, but reversible for R = Ph. Single crystal X-ray structures have been determined for three of the methyl ester-substituted stilbazolium salts and for the Cl⁻ salts of their picolinium precursors. Time-dependent density functional theory calculations afford reasonable predictions of ICT energies, but greater rigour is necessary for -NPh₂ derivatives. The four new acid-functionalized dyes give moderate sensitization efficiencies (ca. 0.2%) when using TiO₂-based photoanodes, with relatively higher values for R = Ph vs Me, while larger efficiencies (up to 0.8%) are achieved with ZnO substrates.     

Synthesis,structure and norbornene polymerization activity of a bulky β-diketiminato palladium(II) complex

A new bulky β-diketiminato palladium(II) complex was synthesized by direct reaction of (ⁱPr₂Ph)₂nacnacH ((ⁱPr₂Ph)₂nacnac = CH{C(Me)N(C₆H₃-2,6-ⁱPr₂)}₂) with Pd(OAc)₂ which yielded [(ⁱPr₂Ph)₂nacnac]Pd(OAc) as a mononuclear species with chelating nacnac and acetato ligands. Preliminary investigations into the polymerization of norbornene in the presence of BF₃OEt₂ were performed.     

Structure and Spectral Characteristics of 3D-Supramolecular Coordination Polymers Based on Copper Cyanide and Dimethylquinoxaline

The reactions of K₃[Cu(CN)₄], R₃SnCl (R = Me or ph) and 2,3-dimethyl quinoxaline (dmqox) in H₂O/acetonitrile media at room temperature afford the 3D-supramolecular coordination polymers (SCP) ³_￥ [ \textCu ₂ ( \textCN ) ₂ \textdmqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 2} {\text{dmqox}}} \right] , 1 and ³_￥ [ \textCu ₂ ( \textCN ) ₄ ·( \textPh ₃ \textSn ) ₂ ·\textdmqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 4} \cdot \left( {{\text{Ph}}_{ 3} {\text{Sn}}} \right)_{ 2} \cdot {\text{dmqox}}} \right] , 2. The structure of the tin free 1 consists of parallel zigzag chains connected by dmqox to form 2D-sheets containing hexagonal 18-atom fused Cu₆(CN)₄(dmqox)₂ rings. The interwoven sheets along the a axis are close packed by extensive H-bonds developing 3D-network structure. The structures of 1 and 2 are investigated by elemental analysis IR, NMR and mass spectra. The ESI⁺ and ESI⁻ mass spectra of 2 support its polymeric nature while the ESI⁺ mass spectrum confirms the expected M. W. suggested by elemental analysis. The ¹³C-NMR spectrum of 2 supports the fact that the network structure of 2 contains the rhombic [Cu₂(μ₃-CN)₂] motif. The structure of 2 was compared with the structure of the reported prototype ³_￥ [ \textCu ₂ ( \textCN ) ₄ ·( \textPh ₃ \textSn ) ₂ ·\textqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 4} \cdot \left( {{\text{Ph}}_{ 3} {\text{Sn}}} \right)_{ 2} \cdot {\text{qox}}} \right] as well as the other related structures.     

Chemical and electrochemical behaviour of nickel ions in the ZnCl2-2NaCl melt at 450°C

The stability of nickel chloride and oxide as well as the electrochemical behaviour of the Ni²⁺ ion have been studied in ZnCl₂-2NaCl melts at 450°C by means of X-ray diffractions (XRD), potentiometry, cyclic voltammetry, chronoamperometry and chronopotentiometry. The standard potential of the redox couple Ni(II)/Ni(O) and solubility product of nickel oxide have been determined (E°Ni(s)/Ni(II) = ?1.006 ± 0.001 V (against Cl₂(1 atm)/Cl^?), pKs = 4.8 ± 0.1 in molality scale). These results have allowed the construction of E-pO^2? equilibrium diagrams. Nickel (II) reduction is close to the reversibility according to the scheme: $${\text{NiCl}}_{\text{2}} ({\text{solvated}}){\text{ + 2e}}^ - \Rightarrow {\text{Ni(s) + 2Cl}}^ - $$ with a diffusion coefficient, D _Ni, close to 3 × 10 ^?6cm²s^?1.     

Syntheses,characterization and properties of manganese,cobalt and copper complexes from chelate N-donor ligands

2-[(S)-4-isopropyl-2-oxazolyl]quinoline (L¹) and 2-[(S)-4-phenyl − 2-oxazolyl]quinoline (L²) react with manganese, cobalt and copper salts to yield four new complexes: [Mn₂(L¹)₂]Cl₂ (1), {[Co(L¹)₂]₂(OH)}(ClO₄)₃ (2), [Cu₂I₂(L¹)₂] (3), and {[Cu(L²)₂]₂(OH)}(BF₄)₃·H₂O (4), which were fully characterized by single-crystal and powder X-ray diffraction, IR, elemental and thermogravimetric analyses. Complexes 1–4 all show dinuclear structure. Two metal ions are bridged by Cl⁻ in 1, by OH^– in 2 and 4, and by I⁻ in 3. Moreover, non-linear optical, and ferroelectric and magnetic properties have been investigated.     

Polymeric [(R4N){(Me3Sn)2OH}Ni(CN)4]n: from layers (R=nC4H9) to infinite ribbons (R=nC5H11)

In the presence of (nC₅H₁₁)₄N⁺ ions, the earlier described almost planar 14-membered ring system [{(Me₃Sn)₂OH}₂{Ni(CN)₄}₂]²⁻ polymerizes via O–H⋯NC hydrogen bonds to straight, infinite ribbons, while in the presence of the slightly smaller (nC₄H₉)₄N⁺ ion a faintly puckered 2-D framework had been obtained. The dimorphism of the polymeric anion seems to be controlled by weak C–H⋯NC hydrogen bonds.     

Two novel three-dimensional coordination polymers with [Ag(CN)2]− as bridging ligands: synthesis and structural characterization of {KMn[Ag(CN)2]3(H2O) }n and {Mn[Ag(CN)2]2(bpy)2}n (bpy=4,4′-bipyridine)

Two novel three-dimensional coordination polymers {KMn[Ag(CN)₂]₃(H₂O)}_n 1 and {Mn[Ag(CN)₂(bpy)]₂}_n 2 have been prepared and structurally as well as magnetically characterized. In both compounds, the three-dimensional networks are constructed entirely by coordinative linkages with all the CN⁻ anions of [Ag(CN)₂]⁻, bpy and water ligands involved in bridging and the novel 3-D structure of 1 is unprecedented.     

Preparation of star polymers based on polystyrene or poly(styrene-b-N-isopropyl acrylamide) and divinylbenzene via reversible addition-fragmentation chain transfer polymerization

Star polymers based on styrene/divinyl benzene (St/DVB) and PSt-b-poly(N-isopropyl acrylamide) (NIPAAM)/DVB have been successively prepared by ‘arm-first’ method via reversible addition-fragmentation chain transfer (RAFT) polymerization. The linear macro RAFT agent PSt-SC(S)Ph was prepared by RAFT polymerization of St using benzyl dithiobenzoate and AIBN as RAFT agent and initiator. Successive RAFT polymerization of NIPAAM with PSt-SC(S)Ph as macro RAFT agent to afford diblock copolymer, PSt-b-PNIPAAM-SC(S)Ph. The coupling reactions of PSt-SC(S)Ph or PSt-b-PNIPAAM-SC(S)Ph in the presence of DVB produced the star copolymers, C(PSt)_n or C(PSt-b-PNIPAAM)_n. The molar ratio of DVB/PSt-SC(S)Ph and polymerization time influenced the yields, molecular weight and distribution of the star-shaped polymers, which was characterized by ¹H NMR and IR spectra, GPC measurements as well as DLS.     

Positive polyacetylene electrodes in aqueous electrolytes

Polyacetylene films, contacted with platinum mesh, have been polarized anodically in aqueous H₂SO₄, HClO₄, HBF₄ and H₂F₂ of medium concentrations (30–70 wt%). Two oxidation peaks are observed, the equivalents of which are 1 $${\text{(1) 0}}{\text{.045 F mol}}^{ - {\text{1}}} {\text{ CH (2) 0}}{\text{.23 F mol}}^{ - {\text{1}}} {\text{ CH}}$$ The potential of the Process 1 decreases linearly with increasing acid concentration by 20–40 mV mol^?1 dm^?3, while the potential of Peak 2 exhibits normal Nernst behaviour (about + 60 mV decade^?1. Process 1 is partially reversible, while Process 2 is totally irreversible. From these findings for Process 1 we conclude the reversible insertion of anions into the polyacetylene host lattice, which is primarily oxidized to the polyradical cation, with the co-insertion of acid molecules HA to yield the insertion compound [(CH)⁺·yA^?·vyHA] _x y?4.5% andv=1.5 for H₂SO₄ and HClO₄. In the course of Process 2, the polymer is irreversibly oxidized according to $$( - ^ \cdot {\text{CH}} \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot ^ \oplus {\text{ CH}} - )_{x/2} + 2{\text{H}}_{\text{2}} {\text{O}} \to ( - \mathop {\text{C}}\limits_{\mathop \parallel \limits_{\text{O}} } \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \mathop {\text{C}}\limits_{\mathop \parallel \limits_{\text{O}} } - )_{x/2} + 6{\text{H}}^{\text{ + }} + 5e^ - $$ As this process occurs to some extent even in the potential region of Process 1, a continuous degradation of the host lattice occurs upon cycling.     

Excess molar enthalpies of ternary and constituent binary systems {1,2-dichloropropane+2-propanol+2-butanol} at T=298.15 K

Ternary excess molar enthalpies at T=298.15 K and P=101.3 kPa for the system of {1,2-dichloropropane+2-propanol+2-butanol} and their constituent binary systems {1,2-DCP+2-propanol}, {1,2-DCP+2-butanol}, and {2-propanol+2-butanol} have been measured over the whole composition range using an isothermal micro-calorimeter with flow-mixing cell. All of the binary and ternary systems, including three pseudobinary systems, show endothermic behavior except for the binary mixture {2-propanol+2-butanol}, which shows small exothermicity. The Redlich-Kister equation was used to correlate the binary H _{m, ij} ^E data, and the Morris equation to correlate the ternary H _{m, 123} ^E data. Comparisons between the Morris and Radojkovi equations for the prediction of H _m,123 ^E have been also made. The experimental results have been qualitatively discussed in terms of self-association, isomeric effect and chain length among molecules.     

A new lead(II) inorganic–organic hybrid of the P,P′-diphenylmethylene-diphosphinate ligand: synthesis and X-ray characterization of the [Pb(CH2(P(Ph)O2)2)] complex

By reaction of lead(II) nitrate with P,P^′-diphenylmethylenediphosphinic acid in water solution a new inorganic–organic hybrid of formula [Pb(CH₂(P(Ph)O₂)₂)] has been synthesized and structurally characterized. The complex displays a polymeric columnar structure, the column being formed by two intersecting sinusoidal ribbons of lead(II) ions bridged by bifunctional phosphinate ligands. The intersections of the ribbons are constituted by dimeric units of pentacoordinated lead(II) ions.     

Synthesis and structural study of tri- and dinuclear palladium complexes of 2,6-bis(diphenylphosphino)pyridine

The bridging ligand 2,6-bis(diphenylphosphino)pyridine, L, was used to synthesize two palladium complexes: Pd₃Cl₆(μ-L)₃ has a C₂ axis passing through an 18-membered macrocyclic ring, in which two cis- and one trans-coordinated palladium(II) atoms are alternately bridged by three L ligands; [Pd₂(μ-L)₂]²⁺ exhibits a rare coordination mode in which two metal–metal bonded palladium(I) atoms (Pd–Pd = 2.5525(7) Å) are each P, N-chelated by one ligand and connected to the bridging phosphorus atom of the other ligand.     

Chemoselective Ruthenium‐Catalyzed Reduction of Acid Chlorides to Aldehydes with Dimethylphenylsilane

A variety of aromatic and alkyl acid chlorides can be selectively converted into aldehydes using dimethylphenyl silane (HSiMe₂Ph) as the reducing reagent in the presence of the cationic ruthenium catalyst {Cp[(i‐Pr)₃P]Ru(NCMe)₂}⁺ [PF₆]⁻. The reactions proceed under very mild conditions and are tolerant to many functional groups.     

Reaction of Aryl Iodides with (PCP)Pd(II)—Alkyl and Aryl Complexes: Mechanistic Aspects of Carbon—Carbon Bond Formation

The reaction of the PCP-type complex Pd(Me){2,6-(ⁱPr₂PCH₂)₂C₆H₃}( 3 ) with phenyl iodide results in the formation of Pd(I){2,6-(ⁱPr₂PCH₂)₂C₆H₃} ( 5 ), methyl iodide, toluene, and biphenyl. Formation of Pd(Ph){2,6-(ⁱPr₂PCH₂)₂C₆H₃}( 4 ) is observed during the reaction by ³¹P NMR. Reaction of 4 with aryl iodides results in the formation of 5 and Ph–Ph, Ph–Ar, and Ar–Ar, products indicative of a radical reaction. Under pseudo-first-order conditions, the rates of the reactions follow the order p-OMe > p-Me > H > p-NO₂ > m-Cl. The reaction is likely to involve electron transfer from 4 to the aryl iodide followed by fast decomposition of a postulated radical cation [Pd(Ph){2,6-(ⁱPr₂PCH₂)₂C₆H₃}]^+. ( 4 ^+.) to give a phenyl radical and [Pd{2,6-(ⁱPr₂PCH₂)₂C₆H₃}]⁺ ( 6 ⁺). Facile decomposition of the aryl iodide radical anion generates an aryl radical and I⁻. Recombination of aryl radicals gives rise to mixed biaryls, and 6 ⁺ combines with I⁻ to give 5 .     

Synthesis and characterization of polyimides and co-polyimides having pendant benzoic acid moiety

A novel diamine monomer, 2,4-diamino-4′-carboxy diphenyl ether had been synthesized. Several polyimides were prepared by reacting this diamine with commercially available dianhydrides, such as benzophenone tetracarboxylic acid dianhydride (BTDA), 4,4′-bis{hexafluoroisopropylidene bis (phthalic anhydride)}(6-FDA), oxydiphthalic anhydride (ODPA) and 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA). Furthermore, copolymers from the resulting diamine and oxydianiline (ODA) with 6 FDA were also synthesized. The inherent viscosities of the polymers were 0.42-0.67 dl g⁻¹. The polymers have good solubility in polar aprotic solvents, high thermal stability up to 410 °C in nitrogen and high glass transition temperatures (T_g) ranging from 260-330 °C. These polymers formed tough flexible films by solution casting.     

Ternary and constituent binary excess molar enthalpies of {1,2-dichloropropane + 2-pentanol + 3-pentanol} at T=298.15K

Excess molar enthalpies for the ternary system of {1,2-dichloropropane (1,2-DCP)+2-pentanol+3-pentanol} and their constituent binary mixtures {1,2-DCP+2-pentanol}, {1,2-DCP+3-pentanol}, and {2-pentanol+3-pentanol} have been measured over the whole range of composition using an isothermal micro-calorimeter with flow-mixing cell at T=298.15 K and atmospheric pressure. The experimental excess molar enthalpies of all the binaries and ternary mixture, including three pseudo-binary mixtures, are positive (endothermic effect) throughout the mole fraction range, except for the binary mixture {2-pentanol+3-pentanol} in which shows a small negative values over the entire composition range. The experimental binary H _{m, ij} ^E data were fitted to Redlich-Kister equation, and the Cibulka and the Morris equations were employed to correlate the ternary H _{m, 123} ^E data. Several empirical equations for predicting ternary excess enthalpies from constituent binary mixing data have been also examined and compared. The experimental results have been qualitatively discussed in terms of molecular interactions.     

Carbonato- and methanediolato(-2)-bridged nickel(II) coordination clusters from the use of N-salicylidene-4-methyl-o-aminophenol

The use of N-salicylidene-4-methyl-o-aminophenol in nickel(II) pivalate chemistry has provided access to structurally and magnetically interesting {Ni^II₆Na^I₄} and {Ni^II₆} clusters possessing carbonato and methanediolato(-2) ligands, respectively, with novel coordination modes.     

Magnetic properties of ferrites-cobaltites Bi1 − x La x Fe1 − x Co x O3 (1.0 ≥ x ≥ 0.7) with a perovskite structure

The molar magnetic susceptibility (χ_mol) of Bi_{1 ? x} La _x Fe_{1 ? x} Co _x O₃ solid solutions (x = 1.0, 0.9, 0.8, or 0.7) with a crystal structure of rhombohedrally distorted perovskite (R $\bar 3$ c) has been investigated in the temperature range of 5–300 K in a 0.86 T magnetic field. In the temperature range where χ_mol depends on temperature T according to the Curie-Weiss law, the resulting effective magnetic moments of Fe³⁺ and Co³⁺ ions ( $\mu _{eff,Fe^{3 + } ,Co^{3 + } ,} \mu _{eff,Fe^{3 + } } $ and $\mu _{eff,Co^{3 + } } $ ) have been determined for the solid solutions under study. Fe³⁺ ions in the solid solutions have been found to be in the mixed intermediate spin (IS) and high spin (HS) states ( $\mu _{eff,Fe^{3 + } } $ is 4.26μ_B and 4.68μ_B for the temperature range of 5–100 and 150–300 K, respectively). It is shown that 8% Co³⁺ ions in LaCoO₃ at 5–19 K are in the paramagnetic IS state and they determine to a great extent the magnetic susceptibility. It is established that only 9% and 18% Co³⁺ ions in Bi_{1 ? x} La _x Fe_{1 ? x} Co _x O₃ solid solutions (x = 0.9 or 0.8) are in the paramagnetic IS state in the temperature ranges of 5–30 and 5–110 K, respectively, while the other ions are diamagnetic.