Cobalt(II), nickel(II), copper(II) and copper(I) complexes of 2-mercapto-5-methyl-1,3,4-thiadiazole and 2,5-bis(methylmercapto)-1,3,4-thiadiazole

Summary Some cobalt(II), nickel(II), copper(II) and copper(I) complexes of 2-mercapto-5-methyl-1,3,4-thiadiazole (mttz) and 2,5-bis(methylmercapto)-1,3,4-thiadiazole (bmttz) have been prepared and studied by conductometric and magnetochemical methods and by electronic and i. r. spectroscopy. The complexes CoX₂ · 2L (L=mttz, X=Cl, Br or I; L=bmttz, X=Br or I), CoCl₂ · bmttz are pseudotetrahedral, and the complexes NiX₂ · mttz (X=Cl or Br), NiCl₂ · 1.3 bmttz, NiBr₂ · 1.5 bmttz are pseudooctahedral. The complex Co₃(OAc)₂ · 4(mttz-H) · 2H₂O has an undefinite constitution. The polynuclear complexes CuCl₂ · 1.3 mttz and CuBr₂ · 1.2 mttz contain presumably pseudotetrahedral chromophores, the chloride having a subnormal magnetic moment. The CuX₂ · 2 bmttz (X=Cl, Br or NO₃) complexes have a six coordination with bridging ligand molecules. In the CuX · 2 mttz (X=Cl, Br or ClO₄) complexes the anions are coordinated, while in the CuClO₄ · 2 bmttz complex the perchlorate anion is ionically bonded.     

Coordination polymers formed by diorganotin dichlorides with 2,5-bis(4-pyridyl)-1,3,4-thiadiazole

Dichlorodimethyltin and dichlorodiphenyltin form 1:1 adducts with 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (L1). Mössbauer spectra of the compounds SnCl₂(CH₃)₂ · L1 (1) and SnCl₂(C₆H₅)₂ · L1 · 0.3CH₂Cl₂ (2) are consistent with a monodimensional polymeric structure containing L1 as a bifunctional bridging ligand. The octahedral coordination geometry at the tin atom is very distorted, with a C-Sn-C bond angle of about 150° for both 1 and 2.     

Nickel(II) and copper(II) complexes of 2,5-dimethyl-1,3,4-thiadiazole

Summary Nickel(II) and copper(II) complexes of 2,5-dimethyl-1,3,4-thiadiazole Ni(DTZ)X₂ (X = Cl or Br) and M(DTZ)₂X₂ (M = Ni, X = 1 or N03; M = Cu, X = Cl, Br or NO₃) have been prepared. The i.r. spectra show that in all the complexes the ligand is N,N- or N-bonded to the metal while the sulfur atom does not participate in coordination, and that the halide ions are coordinated forming terminal M-X bonds. The NO ₃ ^- group is coordinated in both the nitrato complexes. Magnetic moments of 3.07–3.29 B.M. for the nickel(II) and 1.86–1.92 B.M. for the copper(II) complexes were observed. The Ni(DTZ)X₂ complexes have a pseudo-tetrahedral [N₂X₂] coordination with N,N-bridging ligand molecules. The Ni(DTZ)₂X₂ and Cu(DTZ)₂X₂ complexes, with predominantly monodentate ligand, involve six-coordinate metal atoms with strong equatorial [N₂X₂] bonds and weaker axial bonds.Author to whom all correspondence should be directed.     

Synthesis, crystal structure, spectroscopy and magnetic properties of a dinuclear Cu complex with 3,5-bis(2-pyridyl)pyrazole bridging ligand

A dinuclear Cu^II complex [Cu₂(bpp)₂(H₂O)₂](ClO₄)₂ (1) with 3,5-bis(2-pyridyl)pyrazole (Hbpp), has been synthesized and characterized by elemental analyses, thermal analysis, conductance, UV-vis and IR spectra. The crystal structure of 1, determined by X-ray diffraction technique, reveals that two centrosymmetric Cu^II centers are bridged by a pair of tetradentate anionic bpp ligands, adopting a square-pyramidal environment with the water ligand occupying the axial site. An interesting feature of this structure is the formation of a two-dimensional supramolecular network through O-H?O hydrogen bonds between the water moieties of the cationic [Cu₂(bpp)₂(H₂O)₂]²⁺ subunits and perchlorate anions. The magnetic properties of 1 have been investigated by variable-temperature magnetic susceptibility and EPR measurements. Very strong antiferromagnetic interaction between the Cu^II centers (with H=−JS₁S₂, J=−368.3 cm⁻¹) has been observed, and the magneto-structural correlations was analyzed.     

Bis[3,6-bis(6-methyl-2-pyridyl)pyridazine-κ2N2,N3]chlorocopper(II) perchlorate

The title compound, [CuCl(C₁₆H₁₄N₄)₂]ClO₄, consists of a mononuclear complex cation and a perchlorate anion. The coordination of the copper(II) ion exhibits a trigonal bipyramidal geometry, where the equatorial plane is composed of the Cl atom and two N atoms of the two pyridazine rings, and the axial positions are occupied by the N atoms of two methyl­pyridine rings.     

Synthesis and characterization of new polyhydrazides based on 2,5-bis(mercapto-acetichydrazide)-1,3,4-thiadiazole moiety

New interesting class of novel polyhydrazides containing 1,3,4-thiadiazole moieties in the main chain was synthesized. A solution polycondensation technique was used in the synthesis of these polymers. The new monomer namely: 2,5-bis(mercapto-acetichydrazide)-1,3,4-thiadiazole III was synthesized from the nucleophilic replacement of 2,5-dimercapto-1,3,5-thiadiazole I with ethylchloroacetate, followed by hydrazinolysis. The model compound VII was synthesized from the monomer 2,5-bis(mercapto-acetichydrazide)-1,3,4-thiadiazole III with benzoyl chloride and characterized by ¹H- NMR, IR, and elemental analyses. The polyhydrazides were synthesized from the polymerization of monomer III with 4,4^′-biphenic, 3,3^′-azodibenzoyl, 4,4^′-azodibenzoyl dichlorides. These polymers were characterized by elemental and spectral analyses, viscometry and solubility. The thermal properties of these polymers were determined by thermal gravimetric analyses, and differential thermal analysis, and correlated with their structure. The crystallinity of some polymers was tested by X-ray analyses.     

Synthesis and characterization of 1,3,4,-thiadiazole-containing polyethers from 2,5-bis (4-fluorophenyl)-1,3,4-thiadiazole and various aromatic diols

Seven 1,3,4-thiadiazole-containing polyethers with reduced viscosities of 0.27–1.44 dL/g were synthesized by the high-temperature solution polycondensation of novel activated difluoride, 2,5-bis (4-fluorophenyl)-1,3,4-thiadiazole, with aromatic diols possessing a variety of ring structures. The expected chemical structures were confirmed by IR and ¹H-NMR spectroscopy and elemental analysis. Of all the polymers, three polyethers were highly crystalline and soluble only in limited solvents such as concentrated sulfuric acid. The other polyethers were amorphous and dissolved easily in a variety of organic solvents including N-methyl-2-pyrrolidone (NMP), phenols, and chlorinated hydrocarbons. Colorless to slightly yellow-colored, transparent, and tough films could be cast from the NMP solutions of the amorphous polyethers. The mechanical properties of the films were excellent, and their tensile strength, elongation at break, and tensile moduli were in the ranges of 48–72 MPa, 5–7%, and 1.3–1.9 GPa, respectively. The amorphous polyethers had high glass transition temperatures of 204–299°C. All the polyethers were highly thermally and thermooxidatively stable and exhibited no weight loss up to 400°C, with 10% weight loss being recorded at 464–513°C in air. © 1994 John Wiley & Sons, Inc.     

Di-radical dinuclear copper complex: synthesis,structure, and magnetic properties

The reaction of Cu(Ac)₂·4H₂O with 2-[(3,5-dichloro-2-hydroxy-benzylidene)-amino]-2hydroxymethyl-propane-1,3-diol (H₄L) and 4,4′-bipyridyl-N,N′-dioxide (4,4′-bipy-NO) in DMF under solvothermal conditions leads to the formation of a di-radical dinuclear copper complex [Cu₂(4,4′-bipy-NO)(dcdmap)₄] (1) (dcdmap is the anion of 2,4-dichloro-6dimethylaminomethyl-phenol, synthesized by an in situ reaction). Compound 1 was characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Complex 1 displays dominant anti-ferromagnetic interaction between oxyradicals and copper ion and oxyradical.     

Complexes with diimine ligands. Syntheses and magnetic behaviour of dinuclear complexes of copper(II), nickel(II) and cobalt(II) with 2,5-bis(2-pyridyl)pyrazine

Summary The synthesis, characterization and voltammetric and magnetic behaviour of a series of dinuclear complexes -(2,5-DPP)[M(hfacac)₂]₂, in which hfacac is hexafluoro-acetylacetonate, 2,5-DPP is 2,5-bis(2-pyridyl)pyrazine and M = copper(II), nickel(II) and cobalt(II), are described. As with the dinuclear complexes derived from 2,3-bis(2-pyridyl)-pyrazine (2,3-DPP) and analogous ligands, magnetic measurements show that these systems are not coupled. On the basis of magnetic data, we propose that, in contrast to related ligands such as 2,2-bipyridyl, the coordinated 2,5-DPP cannot be planar.     

Synthesis, characterisation and liquid crystal properties of 2,5-bis[5-alkyl(alkoxy)phenyl-1,3,4-oxadiazole]bromobenzenes

A series of new thermal bilateral liquid crystal compounds with the phenylenebis-1,3,4-oxadiazole structure was synthesised. The molecular structures of the oxadiazole compounds were confirmed by FT-IR and ¹H NMR spectroscopy, elemental analysis and mass spectrometry. Thermogravimetric analysis indicates that the compounds in an atmosphere of nitrogen have good thermal stability. Measurements using differential scanning calorimetry, polarising optical microscopy and temperature-dependent wide-angle X-ray diffraction indicated that the liquid crystalline properties are related to the length of the end groups. When the end group was tert-butyl or alkoxy with four and six carbons, the compounds exhibit no liquid crystal phase. However, compounds with end groups containing more than eight carbons show significant bidirectional thermally-induced liquid crystal properties and the structure of the liquid crystal phase is the lamellar smectic A phase. All the compounds exhibit blue fluorescence.     

Synthesis,characterization, crystal structure and chemical behavior of [1,1-bis(diphenylphosphinomethyl)ethene]ruthenium(II) complex toward primary alkylamine addition

Reaction of the ruthenium phosphine complex [RuCl₂(PPh₃)₃] 1 with an unsaturated functionalized diphosphine ligand, namely 1,1-bis(diphenyl-phosphinomethyl)ethene, H₂C=C(CH₂PPh₂)₂, (dppme) gave trans-Cl₂Ru(dppme)₂ 2. Complex 2 served as a precursor for the synthesis of trans-Cl₂Ru(dppme)(alkylamine)₂ complexes 3–5 by reaction with RNH₂. All these complexes were characterized by spectroscopic techniques and by elemental analysis. The solid-state structure of complex 2 was determined by X-ray crystallography.     

A tetranuclear copper(II) complex: crystal structure,assembly, EPR,electrochemistry and magnetism

A tetranuclear copper(II) complex, [Cu₂L]₂(ClO₄)₂ · 4H₂O (1), where H₃L = N,N′-bis(4-(3′-formyl-5′-chlorosalicyclidene)iminoethyl)-4-chloro-2,6-bimethyliminophenol, has been synthesized and structurally characterized by ES-MS, IR and X-ray crystallography. The complex is a dimer of two dinuclear copper(II) acylic enantiomorph subunits ([Cu₂L]ClO₄ · 2H₂O), held together by π–π, coordination and hydrogen bond interactions. The Cu–Cu separation in each subunit, bridged by one phenoxide, is 3.228 Å, and the shortest distance of Cu–Cu between the two subunits is 3.252 Å. There are two crystallographically unique copper(II) environments, one (Cu1) is square-based pyramidal with O₃N₂ donor set, another (Cu2) square planar with O₂N₂ donor set. The cyclic voltammogram of the complex shows that it undergoes two stepwise reduction processes, E _pc = ?0.707 and ?0.850 V, respectively. Magnetic measurements in the 2–300 K range indicate strong antiferromagnetic interactions between Cu(II) ions in each subunit with the exchange constant J = ?211(2) cm^?1. The observation has been rationalized on the basis of the effective magnetic pathway.     

Synthesis and crystal structure of dinuclear nickel (Ⅱ) complex

The crystal structure of Ni(Ⅱ) complex with 3-hydroxyl-1, 5-diazacycloheptane-N, N'-diacetate was determined by X-ray diffraction method. Crystal data for Ni2 (C9H14N2O5)2·2H2O: monoclinic, space group P21/n, a = 1.1717(5), b = 0.9794(3), c = 1.2971(2) nm, β= 96.62(3), V= 1.4786(7) nm3, Dc = 1.377 g/cm3, Z = 2,μ=13.321 cm-1 (Mo-Kα), F(000)=640. The final R and Rw are 0.075 and 0.089 respectively. The Ni(Ⅱ) ion forms 2:2 complex with ligand. Two ligands are bridged by two Ni(Ⅱ) atoms which are bridged by two O atoms. Every Ni(Ⅱ) is coordinated by two N atoms and four 0 atoms. The coordination polyhedron of the Ni(Ⅱ) ion is a distorted octahedron.