New μ-oxo-bridged tetranuclear Cu(II) complex with Schiff-base ligand: Synthesis,crystal structure and magnetic properties

A new μ-oxo-bridged Cu(II) complex with cubane-like tetranuclear copper(II) complex, [Cu₄(L¹)₄] · 4H₂O (1) (H₂L¹ = 2-(3-methoxy-salicylidene-amino)-benzyl-alcohol), has been prepared, and structurally characterized by X-ray crystallography. Complex 1 crystallized in the monoclinic space group P₂₁/n and has a tetranuclear core of Cu₄O₄. The temperature dependence of magnetic susceptibility measurements shown that complex 1 exhibits a strong antiferromagnetic interaction with J = −103.4 cm⁻¹.     

Synthesis,structure and magnetic properties of a tetranuclear Mn(II) complex with carbohydrazone based ligand

A new tetranuclear complex of Mn(II), [Mn₄(L)₂(CH₃OH)₂(μ-N₃)₄(N₃)₂] ∙ 2(CH₃OH) (1), was synthesized and characterized by spectroscopic methods, single-crystal X-ray diffraction analysis and TGA analysis where HL is bis-[(E)-N′-(phenyl(pyridin-2-yl)methylene)]carbohydrazide. Single crystal X-ray analysis reveals that 1 has a Mn₄ core in which Mn(II) ions are connected by azide and enolate oxygen atoms. IR spectroscopy and X-ray analysis indicate that the carbohydrazone is coordinated to the metal cores as a mononegative ligand in the enol form. The magnetic behavior of 1 was investigated between 2 and 295 K and indicated that the magnetic coupling mediated via azide bridge is ferromagnetic whereas the enolate oxygen mediates antiferromagnetic coupling that leads to overall antiferromagnetic behavior.     

A novel hydroxo-bridged cyclic tetranuclear copper(II) complex using the guanazole ligand: Synthesis,crystal structure and thermal analysis

A novel hydroxo-bridged cyclic tetranuclear copper(II) complex with the guanazole ligand (3,5-diamino-1,2,4-triazole = Hdatrz), [Cu₄(datrz)₄(μ₂-OH)₂(NO₃) (H₂O)₆] · (NO₃) · 5(H₂O) (1) has been synthesised and characterised by X-ray crystallography. In 1, the four copper(II) centres are linked by hydroxo bridges and the N1,N2-coordination of the deprotonated guanazole ligands. The core has considerably short Cu⋯Cu distances in the range of 3.3550(4)–3.3611(4) Å. Thermal analysis of 1 reveals that the cyclic framework constructed with hydroxo and guanazole ligands is stable up to 285 °C.     

Synthesis,structure and magnetic property of a cyanamido bridged trinuclear copper complex

An unusual μ_1,1,3-cyanamido bridged trinuclear copper complex, [(2,2′-bpy)₆Cu₃(NCN)](ClO₄)₄·H₂O (1) (2,2′-bpy = 2,2′-bipyridine), has been synthesized and structurally characterized. Magnetic studies show the existence of large antiferromagnetic coupling between the copper(II) ions.     

A mixed-spin Fe(II) tetranuclear cluster: Preparation,structure and magnetic property

A tetranuclear ferrous cluster, [(phen)₂Fe(II)(CN)₂Fe(II)(bpqa)]₂(PF₄)₄ · H₂O · (CH₃OH)₂ (abbreviated as 1-(PF₆)₄) (bpqa = bis(2-pyridylmethyl)(2-quinolylmethyl)amine, phen = 1,10-phenanthroline), has been synthesized via self-assembly reaction. Single-crystal X-ray diffraction analysis shows that 1-(PF₆)₄ is a tetranuclear cyanide-bridged ferrous cluster, which is crystallized in centrosymmetric C2/c space group of monoclinic crystal system. The temperature (5–300 K) dependent magnetic susceptibility of 1-(PF₆)₄ corresponds to a mixed-spin state with two high spin and two low spin Fe(II) ions within the cluster.     

Synthesis,crystal structure and magnetic properties of a new cyanide-bridged mixed-valence copper(I)/copper(II) clathrate

A unique cyanide-bridge mixed-valence Cu^I/Cu^II clathrate of formula [Cu^I₂(CN)₃][{Cu^II(tren)}₂(μ-CN)](CF₃SO₃)₂ [tren = tris(2-aminoethyl)amine] containing cyanide-bridged [{Cu^II(tren)}₂(μ-CN)]^3 + binuclear cations stacked between anionic honeycomb layered copper(I) cyanide networks, was synthesized and structurally characterized by single crystal X-ray diffraction. Variable-temperature magnetic susceptibility studies showed that the cyanide bridge mediates a strong antiferromagnetic interaction between the copper(II) centers (J = − 160 cm^− 1, the spin Hamiltonian being defined as H = −J S_A⋅S_B).     

Alkoxo- and carboxylato-bridged hexanuclear copper(II) complex: Synthesis,structure and magnetic properties

Reaction of copper(II) nitrate trihydrate with N,N-dimethylethanolamine (dmea) and pivalic acid in methanol led to the hexanuclear copper(II) complex Cu₆(η¹:μ₂-C₄H₁₀NO)₄(η¹:η¹:μ₂-C₅H₉O₂)₄(η¹:μ₁-C₅H₉O₂)₂(μ₃-OH)₂ (1). The crystal structure of 1 indicates that hexametallic centers are bridged by the μ₃-alkoxo, dmea oxygens, and the μ₂-dicarboxylato oxygen atoms of pivalate ions. Furthermore, in the asymmetric unit, three types of copper ions have been found labeled as Cu₁, Cu₂ and Cu₃. The Cu₂ takes a distorted octahedral shape, whereas Cu₁ and Cu₃ adopt square pyramidal geometries. The complex 1 shows strong antiferromagnetic interactions through the oxo groups within the dimeric units (J = − 82.6 to − 25.8 cm^− 1) and weak antiferromagnetic couplings between the dimers (J = − 10.9 and 0.8 cm^− 1).     

Synthesis,crystal structure and nonlinear optical property of cadmium(II) and copper(II) complexes with novel chiral ligand

Two novel metal-organic frameworks (MOFs) [Cd(3-MPCA)₂ · H₂O] · 5.5H₂O (1) and [Cu(3-MPCA)₂ · H₂O] · 4H₂O (2) [3-MPCA⁻ = (1R, 3S)-1,2,2-trimethyl-3-(pyridin-3-ylmethylcarbamoyl)cyclopentanecarboxylate] were hydrothermally synthesized and characterized by X-ray crystallography. Complexes 1 and 2 are homochiral and have similar one-dimensional (1D) chain structure, which are further linked by strong hydrogen bonds to give 3D architectures. There are oxygen hexmers and heptamers from water molecules and carbonyl group in 1 with O⋯O distances and O–O–O angles comparable to the corresponding values in ice. Nonlinear optical measurements on powdered sample of 1 and 2 revealed that they display second-harmonic-generation (SHG) response of 0.8 and 0.3 times of that for urea, respectively.     

Synthesis, crystal structure and luminescent properties of a thiocyanato bridged two-dimensional heteronuclear polymeric complex of cadmium(II) and copper(II)

A novel heteronuclear polymeric complex Cd(SCN)₃Cu(en)₂NO₃ (1) (en = ethylenediamine) has been synthesized and structurally characterized. The Cd(II) atom is surrounded by three S atoms and three N atoms from four 1,3-μ-SCN⁻ and two 1,1,3-μ-SCN⁻ to attain a distorted octahedral coordination geometry. Six Cd(II) centers are linked by twelve thiocyanato bridges to form hexagonal metallocyclic unit [Cd₆(SCN)₁₂] and extend a 2D network. Moreover, a 1,1,3-μ-SCN⁻ links two cadmium and one copper metal atoms. The luminescent properties of 1 in the solid state were investigated.     

Synthesis and crystal structure of three dimensional complex from copper(II) and 1,2,4,5-benzenetetracarboxylate

A copper(II) complex {[Cu(H₂btc) (H₂O)₃]₂(H₄btc)(C₅H₁₁N)₂ · 3H₂O}_n (1) has been synthesized and characterized structurally (H₄btc=1,2,4,5-benzenetetracarboxylic acid). Open channels were formed and can accommodate piperidine molecules. TGA data show that guest water and piperidine molecules are lost at 130 °C.     

Synthesis,crystal structure and magnetic characterization of a dinuclear Mn(II) complex with double end-on azide ligands

A new dinuclear manganese(II) complex [MnL(N₃)₂]₂ · 2CH₃OH 1 has been synthesized and characterized crystallographically and magnetically. L is a tridentate Schiff base ligand which is derived from the reaction of pyridine-2-carbaldehyde and 2-aminoethylbenzimidazole. In the complex 1, each Mn(II) ion is coordinated by one L, one terminal azide ligand and symmetrical double end-on bridging azide ligands. The intermolecular hydrogen bonds extend the structure into a two-dimensional layer. Magnetic determination of 1 indicates that ferromagnetic exchange interaction between the two manganese(II) ions exist in this complex through the double end-on azide bridges.     

Synthesis,crystal structure and self-assembly property of a mixed (phthalocyaninato) (porphyrinato) europium triple-decker complex

A mixed phthalocyaninato and porphyrinato triple-decker complex [Eu₂(Pc)₂(TClPP)] was synthesized and characterized by elemental analysis, FT-IR, UV, and X-ray structure determination. Its self-assembling properties in mixed chloroform/methanol solution were investigated by TEM, SEM and XRD techniques. Investigation revealing the availability of the single crystal, together with the molecular structure, renders it possible to investigate the formation mechanism as well as the molecular packing conformation of self-assembled nanostructures fabricated from this complex in a more confirmed manner.     

One-dimensional inorganic framework consisting of the sandwich-type germanomolybdate and the copper complex linker: Synthesis,crystal structure,and magnetic property

A new heteropolymolybdate, (Him)₈Na₇H₇[Cu(im)₄(CuGeMo₉O₃₃)₂][(CuGeMo₉O₃₃)₂]·41H₂O (1) (im = imidazole), was synthesized and structurally characterized by elemental analysis, IR spectra, UV electronic spectroscopy and X-ray diffraction. Compound 1 exhibits a one-dimensional chain-like framework [Cu(im)₄(CuGeMo₉O₃₃)₂]^10? with isolated [(CuGeMo₉O₃₃)₂]^12? units residing among the chains, which is first observed in sandwich-type germanomolybdate system. Electrocatalytic experiments show that compound 1 exhibits good electrocatalytic activity for nitrite reduction. The magnetic investigation indicates the existence of antiferromagnetic interactions for 1.     

Synthesis,crystal structure and bioactivity of a novel linear trinuclear nickel(II) complex

A novel linear trinuclear nickel(II) complex, [Ni₃(H₂O)₂(DMA)₂(acbshz)₂]·2DMF (DMA = dimethylamine; acbshz = N-acryloyl-5-bromosalicylhydrazide), has been prepared by self-assembly approach. The three nickel atoms arrange in a strictly linear structure, adjacent molecules are linked by intermolecular H bonds to form a 2D infinite wave-like structure. Antibacterial screening data indicate the formation of the trinuclear complex reduced the antimicrobial activity of the ligand.     

Synthesis,crystal structure,characterization and magnetic property of a new organophosphonate-based polyoxovanadate

A novel organophosphonate-based polyoxovanadate, Cs_1·5Na_3.5[H{V₃(H₂O)O₃}{O₃PC- (OH)(CH₃)PO₃}₃]·15H₂O (1) has been synthesized and further investigated by single-crystal X-ray diffraction analysis, IR spectrum, UV–vis spectroscopy, X-ray powder diffraction, thermogravimetric analysis and X-ray photoelectron spectroscopy. Single-crystal X-ray analysis reveals that compound 1 crystallizes in the triclinic space group P-1 with a = 9.506(3) Å, b = 15.150(5) Å, c = 17.915(6) Å, V = 2437.9(14) ų and Z = 2. Compound 1 exhibits a ring-shaped cluster with three branches of the 1-hydroxyethane 1, 1-diphosphonic acid [HEDP = H₂O₃P(OH)C(CH₃)PO₃H₂] ligands. Furthermore, the magnetic property of compound 1 has also been studied.     

Synthesis and structural characterization of a disulphide-bridged tetranuclear palladium(II) complex derived from 3,5-diacetyl 1,2,4-triazole bis(4-ethylthiosemicarbazone)

A novel tetranuclear [Pd₄(μ₂-η²-S₂)(H₂L¹)₂] complex, where H₂L¹ is the anion of 3,5-diacetyl-1,2,4-triazole bis(4-ethylthiosemicarbazone), was synthesized and structurally characterized by single crystal X-ray diffraction. The molecular structure shows an unexpected μ₂-η²-S₂ bridge, which is shared by all the four palladium atoms. Each trideprotonate 3,5-diacetyl-1,2,4-triazole bis(4-ethylthiosemicarbazone) ligand acts as a hexadentate in a symmetrical manner bridging two metal ions through the two adjacent nitrogen atoms of the central triazole ring. The molecular packing is characterized by hydrogen bond interactions to form a 3D supramolecular architecture with channels running down the c¹ axis in which the lattice water molecules are encapsulated.     

Synthesis, characterization and crystal structure of a novel thiocyanate–ruthenium(II) complex

The cis-[Ru(dppb)(Me-bipy)(NCS)₂], dppb = 1,4-bis (diphenylphosphino)butane, Me-bipy = 4,4′-dimethyl-2,2′-bipyridine, and NCS = thiocyanate, was synthesized and characterized by spectroscopic and electrochemical techniques and its structure was determined by crystal X-ray analysis. The crystal structure reveals that the coordination geometry around the Ru(II) center is distorted octahedron where two molecules of thiocyanate are bonded to the ruthenium through nitrogen atom in cis orientation. The half-wave formal potential value E_1/2 = 0.8 V (versus Ag/AgCl) observed is considerable higher than that for the cis-[RuCl₂(dppb)(Me-bipy)] complex, E_1/2 = 0.6 V (versus Ag/AgCl), well illustrating the strong π-acceptor effect the NCS ligand toward the backbonding interaction with the Ru(II) metal center. The MLCT absorption bands of the thiocyanate complex present a higher molar absorptivity (about 12%) compared with the cis-[RuCl₂(dppb)(Me-bipy)] complex, in the same experimental conditions. These properties make the complex potentially promising for the photosensitization process.     

Synthesis,structure and properties of a new NH-1,2,3-triazole-based octanuclear copper(II) complex

An octanuclear copper complex, [Cu₈(L)₁₀(OH)₄Cl₂·(DMF)₂]·2DMF ( HL= 4-(2-bromophenyl)-2H-1,2,3-triazole) has been synthesized. Single crystal diffraction reveals that it crystallizes in the triclinic space group P − 1. The complex shows fluorescent quenching compared with the free ligand. The {Cu₈} displays overall strong antiferromagnetic (AF) coupling via hydroxyl groups, κ₂-N,N-trizaoles and κ₃-N,N,N-trizaoles, and the complex exhibits AF ordering under low temperature with T_N = 8.5 K.