Influence of organic carboxylic acids on self-assembly of silver(I) complexes containing 1,2-bis(4-pyridyl)ethane ligands

Four silver(I) complexes, namely [Ag₂(bpe)₂](bdc)·8H₂O (1), [Ag₂(bpe)₂(da)]·4H₂O (2), [Ag₄(bpe)₃(bptc)]·9H₂O (3), and Ag(bpe)₂(bpdc)₂ (4), have been successfully synthesized by the reactions between AgNO₃, 1,2-bis(4-pyridyl)ethane (bpe) and different carboxylic acids, including 1,3-benzenedicarboxylic acid (H₂bdc), diphenic acid (H₂da), 3,3′,4,4′-biphenyltetracarboxylic acid (H₄bptc), and 2,2′-bipyridine-3,3′-dicarboxylic acid (H₂bpdc). All four compounds were characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. In (1), the Ag(I) atoms, in linear geometry, are joined into 1-D infinite cationic bpe-silver chains, and discrete bdc²⁻ anions compensate the charge of the crystal structure. In (2), the Ag(I) atoms, adopting tetrahedral and trigonal geometries, are linked by bpe and da²⁻ ligands into neutral double chains. In (3), the Ag(I) atoms, in T-shaped and linear environments, are coordinated by bpe and multidentate bptc⁴⁻ ligands to construct a 2-D network. And in (4), the Ag(I) atoms, with trigonal and T-shaped coordination geometries, are coordinated by bpe and bpdc²⁻ ligands to build up a 3-D framework. The different anions play different and important roles in directing the final crystal structures.     

Synthesis,structures and properties of copper(II) and zinc(II) complexes with 1,2-bis(benzimidazol-2-yl)ethane ligands

Transition Metal Chemistry - 1,2-Bis(benzimidazol-2-yl)ethane (bbe) and its transition metal complexes, [Cu(bbe)Cl2]·DMF (1) and [Zn(bbe)Cl2]2(2), have been synthesized and characterized by...     

Network diversity and supramolecular isomerism in copper(II)/1,2-bis(4-pyridyl)ethane coordination polymers

Reactions of copper(II) sources with 1,2-bis(4-pyridyl)ethane (bpe) yielded metal-organic networks with diverse topologies and dimensionalities. Compounds [Cu(bpe)₂(dmf)₂]_n(ClO₄)_2n·2ndmf (1·2ndmf), [Cu(bpe)₂(dmf)₂]_n(ClO₄)_2n·3.5ndmf (2·3.5ndmf), [Cu(bpe)₂(NO₃)₂]_n·2nH₂O (4·2nH₂O) and [Cu₂(bpe)(O₂CMe)₄]_n·0.7nH₂O (5·0.7nH₂O) have been isolated by altering the copper(II) source, the reaction solvent and the crystallization process. Compounds 1·2ndmf and 2·3.5ndmf consist of cationic [Cu(bpe)₂(dmf)₂]²⁺ repeating units assembled to 1D and 2D (4,4) networks, respectively, and represent supramolecular isomers due to the conformational isomerism of the bridging bpe molecules. Compound 4·2nH₂O consists of neutral mononuclear [Cu(dpe)₂(NO₃)₂] repeating units assembled to inclined interpenetrating (4,4) sheets describing an overall entanglement that is 3D in nature, and compound 5·0.7nH₂O consists of neutral dinuclear repeating units assembled to cross-linked 1D chains.     

Alkyl complexes of palladium(II) with trimethylphosphine and 1,2-bis-(dimethylphosphino)ethane ligands

A number of neutral, mononuclear dialkylpalladium(II) tertiary phosphine complexes of geneal formula cis or trans-PdR₂(PMe₃)₂ and cis-PdR₂ (dmpe) [dmpe = 1,2-bis(dimethylphosphino)ethane], R = Me, CH₂Ph, CH₂CMe₂Ph, CH₂SiMe₃ have been obtained by interaction of magnesium reagents with palladium(II) acetate or trans-Pd(O₂CMe)₂(PMe₃)₂.     

Expanding the family of phospholane-based ligands: 1,2-bis(2,5-diphenylphospholano)ethane

[reaction: see text] 1,2-Bis(2,5-diphenylphospholano)ethane (Ph-BPE) has been synthesized for the first time through employment of an undemanding synthetic pathway. The new ligand exhibits enhanced activity and selectivity over the existing members of the BPE ligand family in rhodium-catalyzed asymmetric hydrogenation.     

Vibrational Spectroscopic Study of [1,2-bis(4-pyridyl)ethane]metal(II) Tetracyanonickelate(II). 2 m-Xylene Clathrates

Four new Hofmann-type clathrates of the form M(bpa)₂Ni(CN)_4· 2m-xylene (M = Mn , Fe , Co and Ni; bpa = 1,2-bis(4-pyridyl)ethane) have been synthesized and characterized by vibrational spectroscopy. The M(bpa)₂Ni(CN)₄ (M = Fe and Co) host structure is similar to the classical Hofmann-type host framework composed of layers of a two dimensional catena-metal tetra--cyanonickelate(II) network, but in M(bpa)₂Ni(CN)₄ (M = Mn and Ni), the Ni(CN)₄ moiety behaves as a bidentate –[NC-Ni(CN)₂-CN–]– unit in the host framework.     

Copper(II) complexes bearing cyclobutanecarboxylate and pyridine ligands: a new series of dinuclear paddle-wheel complexes

Monatshefte für Chemie - Chemical Monthly - Four members of a new series of paddle-wheel copper(II) complexes bearing cyclobutanecarboxylate as bridging ligand with pyridine derived ligands in...     

Copper(I) and copper(II) complexes possessing cross-linked imidazole-phenol ligands: structures and dioxygen reactivity

Catalytic reduction of O2 to H2O, and coupling to membrane proton translocation, occurs at the heterobinuclear heme a3-CuB active site of cytochrome c oxidase. One of the CuB ligated histidines is cross-linked to a neighboring tyrosine (C-N bond; tyrosine C6 and histidine epsilon-nitrogen), and the protic residue of this cross-linked His-Tyr moiety is proposed to participate as both an electron and a proton donor in the catalytic dioxygen reduction event. To provide insight into the chemistry of such a moiety, we have synthesized and characterized tetra- and tridentate pyridylalkylamine chelate ligands {LN4OR and LN3OR (R = H or Me)}, which include an imidazole-phenol (or anisole) cross-link and their copper(I/II) complexes. [CuI(LN4OH)]B(C6F5)4 (1) reacts with dioxygen at -80 degrees C in THF, forming an unstable trans-mu-1,2-peroxodicopper(II)complex, which subsequently converts to a dimeric copper(II)-phenolate complex [{Cu(LN4O-)}2](B(C6F5)4)2 (5a). The close analogue [CuI(LN4OMe)]B(C6F5)4 (3) binds dioxygen reversibly at -80 degrees C in tetrahydrofuran. Stopped-flow kinetics of the reaction [CuI(LN3OH)]ClO4 (2) with O2 in CH2Cl2 indicate a steady formation of the purple dimeric product [{Cu(LN3O-)}2](ClO4)2 (5b), which has been analyzed in the temperature range from -40 to +20 degrees C, DeltaH = -9.6 (6) kJ mol-1, DeltaS = -168 (2) J mol-1 K-1 (k(-40 degrees C) = 1.05(4) x 106 and k(+20 degrees C) = 4.6(2) x 105 M-2 s-1). The X-ray crystal structures of 1, [CuII(LN3OH)(MeOH)(OClO3-)](ClO4) (4), 5a, and 5b are reported.     

Titanium(III) and vanadium(III) chloride complexes with 2-pyridylphenylacetonitrile and 1,2-dicyano-1,2-diphenyl-1,2-di(2′-pyridyl)ethane

Summary 2-Pyridylphenylacetonitrile (ppa) and 1,2-dicyano-1,2-diphenyl-1,2-di(2-pyridyl)ethane (dcppe) react with titanium(III) and vanadium(III) chlorides yielding complexes of formulae: [TiCl₃(ppa)₂], [TiCl₃(ppa)₃], [VCl₃(ppa)], [TiCl₃(dcppe)] and [(VCl₃)₂(dcppe)]. The results obtained suggest pentacoordinated structures for complexes, except for [TiCl₃(ppa)₃] where an hexacoordinated stereochemistry around the metal is proposed.     

Copper(I) and mercury(II) halide complexes of 1,2-bis(diphenylthioylphosphino)hydrazine

The reaction of 1,2-bis(diphenylthioylphosphino)hydrazine (L) with copper(I) and mercury(II) halides affords the complexes, [{CuLX}₂] (X = I, Br or Cl), [HgLX₂] (X = Cl or Br) and the tetrametallic complex, [{L(HgI₂)₂}₂]. Single crystal X-ray structures have been performed on the uncoordinated ligand, L, as well as the complexes [{CuLX}₂] (X = I, Br and Cl), [HgLBr₂] and [{L(HgI₂)₂}₂. The molecules of L exist as dimers as a result of pairs of N–HS hydrogen bonds. The copper(I) complexes are centrosymmetric dimetallic species, the two copper atoms being bridged by L and the X atoms. In all cases the coordination sphere around the Cu atoms is approximately trigonal pyramidal with an ‘S₂X₂’ donor set. The complex, [HgLBr₂], is a distorted tetrahedral monomer with an ‘S₂Br₂’ donor set and L acting as a bidentate thus forming a seven-membered chelate ring. The tetramercury iodo complex, [{L(HgI₂)₂}₂], contains two ‘L(HgI₂)₂’ units linked centrosymmetrically via an I atom from each moiety. The geometry around the Hg atoms is distorted tetrahedral. The influence of hydrogen bonding between the hydrazine backbone hydrogens of L and the coordinated halide ions in for the structures of the metal complexes is discussed.     

Zn(II) and Co(II) 3D Coordination Polymers Based on 2-Iodoterephtalic Acid and 1,2-bis(4-pyridyl)ethane: Structures and Sorption Properties

Metal-organic frameworks [M₂(2-I-bdc)₂bpe] (M = Zn(II) (1), Co(II) (2), 2-I-bdc = 2-iodoterephtalic acid, and bpe = 1,2-bis(4-pyridyl)ethane) were prepared and characterized by X-ray diffractometry. Both compounds retain their 3D structure after the removal of guest DMF molecules. Selectivity of sorption of different organic substrates from the gas phase was investigated for both complexes.     

HF and DFT studies and vibrational spectra of 1,2-bis(2-pyridyl)ethylene and its zinc (II) halide complexes

Ab initio restricted Hartree–Fock and density function theory calculations using BLYP, B3LYP and B3PW91 functionals were carried out to study molecular structure and vibrational spectrum of 1,2-bis(2-pyridyl)ethylene (which is abbreviated as bpe). Comparison of calculated and experimental results indicates the density functional B3LYP and BLYP/6-311G* methods are more accurate in predicting fundamental vibrational frequencies than the scaled other approaches. On the basis of calculated results, assignment of fundamental vibrational modes of bpe was proposed. Complexes of the type Zn(bpe)X₂ [where X = Cl, Br, I] have been studied in the 4000–400 cm⁻¹ region, and assignments of all the observed bands were made. The analysis of the infrared spectra indicates that there is some structure-spectra correlations.     

Far-IR spectra of charge-transfer complexes between IX (X = Cl,Br or I) and trans-1,2-bis(4-pyridyl)ethylene, 1,2-bis(4-pyridyl)ethane and 4,4′-

Far-IR spectra of charge-transfer complexes of trans-1,2-bis(4-pyridyl)ethylene (Bpe), 1,2-bis(4-pyridyl)ethane (Bpa) and 4,4′-bipyridyl (4,4′-     

A thermal decomposition study on cobalt(II) complexes of 1,2-bis(IMINO-4'-antipyrinyl)ethane

The phenomenological, kinetic and mechanistic aspects of thermal decomposition of perchlorate, nitrate, chloride, bromide and iodide complexes of cobalt(II) with the Schiff base 1,2-bis(imino-4'-antipyrinyl)ethane (GA) have been studied by TG and DTG analyses. The kinetic parameters like the activation energy, pre-exponential factor and entropy of activation were calculated. The decomposition reactions follow 'random nucleation with one nucleus on each particle - Mampel model'. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and characterization of a novel cadmium-organic framework with trimesic acid and 1,2-bis(4-pyridyl)ethane

The hydrothermal reaction between Cd(NO(3))(2), trimesic acid (H(3)BTC), 1,2-bis(4-pyridyl)ethane (BPE), and triethylamine under mild conditions yielded, after 3 days, a novel three-dimensional metal-organic framework, [Cd(1.5)(BTC)(BPE)(H(2)O)(2)].(H(2)O), which has been characterized structurally using single-crystal and powder X-ray diffraction, elemental analysis, infrared and Raman spectroscopies, thermogravimetry, and differential scanning calorimetry. The structure exhibits a 2-fold interpenetration of identical [Cd(1.5)(BTC)(BPE)(H(2)O)(2)] single frameworks, described as an unusual (9) net. Crystal data: Cd(1.5)C(21)H(21)N(2)O(9), monoclinic, space group C2/c, with a = 10.8264(5) A, b = 17.4563(5) A, c = 24.2605(11) A, beta = 91.978(2) degrees, V = 4582.2(3) A(3), and Z = 8.     

Syntheses,structures, and fluorescent properties of three Zn(II) and Cu(II) complexes of different ligands derived from 3,6-bis(2-pyridyl)-1,2-dihydro-1,2,4,5-tetrazine

Three supramolecular complexes [Zn(HL₁ )₂(H₂O)₂(ZnCl₄)₂] (1), [Cu(L₂ )₂Cl₂] (2), and [Zn(L₃ )Cl₂] (3) have been synthesized and characterized by single crystal X-ray diffraction analysis (L₁ = 3,5-di(2-pyridyl)-4-amino-1,2,4-triazole, L₂ = 3,5-di(2-pyridyl)-1,2,4-triazole, and L₃ = 2-pyridinecarboxylic acid (pyridin-2-ylmethylene)-hydrazide). In 1, anion–π interactions between Cl^? and the π-systems of L₁ are observed and anion–π, hydrogen bonding and π–π stacking interactions link the two complex units of [Zn(HL₁ )₂(H₂O)₂]⁴⁺ and [ZnCl₄]^2? to form a 3-D supramolecular network. In 2, π–π stacking interactions between aromatic rings of 1,2,4-triazole and pyridine rings are observed; in 3, hydrogen bonding of Cl ··· H–N and π–π stacking interactions between parallel pyridine rings of L ₃ are observed. The mechanisms of rearrangement reactions of L to L₁ –L₃ are discussed. The fluorescent properties for solid 1 and 3 are also investigated.     

Structural diversity and magnetic properties in 1D and 2D azido-bridged cobalt(II) complexes with 1,2-bis(2-pyridyl)ethylene

By utilizing a flexible co-ligand 1,2-bis(2-pyridyl)ethylene (2,2'-bpe), two new azido-bridged cobalt(II) complexes with the formulae [Co?(N?)?(OH?)?(2,2'-bpe)?](n)(2,2'-bpe)(n) (1) and [Co(N?)?(2,2'-bpe)?](n) (2) have been synthesized and structurally characterized. Compound 1 shows an uncommon 1D chain comprised of double EO azido bridged five- and six-coordinated Co(II) geometries in a unique (-5-5-6-)(n) sequence of the coordination number. The 2,2'-bpe acts as a terminal co-ligand and an uncoordinated molecule in the crystal lattice. Moreover the adjacent 1D chain is assembled by C-Hπ interactions and the intermolecular hydrogen bonding between uncoordinated 2,2'-bpe and coordinated water molecules building a 2D layer. Whereas, compound 2 is a 2D coordination network containing the alternating double EO and double EE bridging modes of azides and ditopic 2,2'-bpe bridges. The magnetic investigation of 1 reveals dominant intra-chain ferromagnetic interactions, with the double EO azide-bridge and weak inter-chain antiferromagnetic interactions, with overall metamagnetic behaviour, having magnetic ordering at 6 K. The magnetic behaviour of 2 shows spin-canted antiferromagnetism below a T(N) of 12 K.     

Reactions of 2-pyridylphenylacetonitrile and 1,2-dicyano-1,2-diphenyl-1,2-di(2-pyridyl)ethane with cobalt(II), nickel(II), copper(II) and zinc(II) chlorides and copper(II) bromide

Summary 2-Pyridylphenylacetonitrile (ppa) is oxidized by copper(II) halides in 1,2-dichloroethane to 1,2-dicyano-1,2-diphenyl-1,2-di(2-pyridyl)ethane (dcppe), yielding 41 complexes of dcppe with copper(II) dihalide, [CuX₂(dcppe)₄] (green). Nickel(II) and zinc(II) chlorides react with ppa giving complexes of a general formula [MCl₂(ppa)₂].Dcppe reacts with copper(II), zinc(II) chlorides and copper(II) bromide yielding complexes of formulae [CuCl₂(dcppe)₄] (yellow), [ZnCl₂(dcppe)₂] and [CuBr₂(dcppe)]. No reaction is observed with cobalt(II) and nickel(II) chlorides.     

Determination of mercury species with a resin functionalized with a 1,2-bis(o-aminophenylthio)ethane moiety

A method for the simultaneous preconcentration and determination of Hg(II) and MeHg(I) at the ng ml⁻¹ level has been developed. This method is based on solid phase extraction using a newly synthesized chelating resin containing nitrogen and sulphur donor sites of the 1,2-bis(o-aminophenylthio)ethane moiety that is very selective for mercury. The characterization of the resin has been carried out by elemental analyses, infrared spectral data, thermogravimetric analysis and metal ion capacities. The resin is highly selective for Hg(II) and MeHg(I) with an exchange capacity of 0.38 and 0.30 mmol g⁻¹, respectively. Various parameters like pH, column flow rate, desorbing agents are optimized. Cold vapour atomic absorption spectrometry (CVAAS) was used to measure the concentration of both species of mercury. The calibration graph was linear upto 10 ng ml⁻¹ with a 3σ detection limit of 0.09 ng ml⁻¹. The recovery of Hg(II) and MeHg(I) was found to be 98.9±2.0 and 98.0±1.1%, respectively. The method has been used for routine determination of trace levels of mercury species in natural waters to comply with more stringent regulations.     

Copper(II) complexes with 2,5-bis(2-pyridyl)pyrazine and 1,1,3,3-tetracyano-2-ethoxypropenide anion: Syntheses,crystal structures and magnetic properties

The copper(II) complexes of formula [Cu₂(2,5-dpp)(H₂O)₄(CF₃SO₃)₄] · 2H₂O (1) and [Cu₂(2,5-dpp)(H₂O)₂(tcnoet)₄]_n (2) [2,5-dpp = 2,5-bis(2-pyridyl)pyrazine and tcnoet⁻ = 1,1,3,3-tetracyano-2-ethoxypropenide anion] have been prepared and their structures determined by X-ray crystallographic methods. Compound 1 is a dinuclear complex where the 2,5-dpp molecule acts as a bis-bidentate bridge between the two copper centers, the electroneutrality being achieved by four terminally bound triflate anions. Each copper(II) ion presents an elongated octahedral CuN₂O₄ environment with two nitrogen atoms from 2,5-dpp and two water molecules in the basal plane and two triflate-oxygen atoms in the axial positions. Compound 2 is a zigzag chain of copper(II) ions with regular alternating 2,5-dpp and double tcnoet groups as bridges. Each copper(II) ion exhibits an elongated octahedral CuN₅O surrounding with four nitrogen atoms, two from 2,5-dpp, one from a terminally bound tcnoet and the other from a bridging tcnoet occupying the equatorial positions and a water oxygen and a nitrogen from a monodentate tcnoet in the axial sites. The values of the copper–copper separation across 2,5-dpp are 6.763(1) (1) and 6.754(1) Å (2) whereas that through the double tcnoet bridge is 9.559(1) Å (2). The investigation of the magnetic properties of 1 and 2 in the temperature range 1.9–295 K reveal a Curie law behaviour for 1 and a very weak ferromagnetic interaction for 2. The poor ability of the 2,5-dpp ligand to mediate magnetic interactions between the copper(II) ions in the 2,5-dpp-bridged copper(II) complexes contrast with the somewhat better ability of the pyrazine ring in related pyrazine-bridged copper(II) complexes.