Characterization and crystal structures of copper(II), cobalt(II), and nickel(II) complexes with two kinds of piperidine carboxylic acids

Copper(II) complex with -piperidine-3-carboxylic acid ( -Hpipe-3):[Cu( -pipe-3)₂(H₂O)] and cobalt(II) and nickel(II) complexes with piperidine-4-carboxylic acid (Hpipe-4):[M(Hpipe-4)₂(H₂O)₄]Cl₂ (M: Co, Ni) have been prepared and characterized by means of IR and powder diffuse reflection spectra, thermal analysis, and magnetic susceptibility. The crystal structures of these complexes have been determined by X-ray diffraction. The crystal of [Cu( -pipe-3)₂(H₂O)] is orthorhombic with the space group Pbcn. The copper atom is in a square pyramidal geometry, ligated by two carboxylato oxygen atoms, two nitrogen atoms, and a water molecule. One molecule of this complex consists of either -piperidine-3-carboxylic acid or -piperidine-3-carboxylic acid. The crystals of [M(Hpipe-4)₂(H₂O)₄]Cl₂ are monoclinic with space group P2₁/n. In these complexes the metal atom is in an octahedral geometry ligated by two carboxylato oxygen atoms and four water molecules.     

Hydrothermal syntheses,structures and properties of three cyclic tetranuclear complexes and one 1D chain complex with 3,5-dinitrosalicylate

The hydrothermal reactions of Co(OAc)₂ · 4H₂O, 3,5-dinitrosalicylate (3,5-(NO₂)₂sal) and 2,2′-bipyridine (2,2′-bipy) with different reaction periods give metallamacrocycles 1 and 2 with the same chemical formula Co₄(2,2′-bipy)₄{3,5-(NO₂)₂sal}₄. Replacing Co(OAc)₂ · 4H₂O with Zn(NO₃)₂ · 6H₂O, using the same synthetic procedures, results in the formation of compound [Zn(2,2′-bipy){3,5-(NO₂)₂sal}]_n (3) with a 1D chain structure and the metallamacrocycle compound Zn₄(2,2′-bipy)₄{3,5-(NO₂)₂sal}₄ (4). Compounds 1 and 2 crystallize as two different polymorphs of cyclic tetranuclear compounds. Compounds 3 and 4 are polymorphic too. The compounds 1 and 4 are isomorphous. The weak coordination interactions have significant influence on the spacial orientations of the 3,5-(NO₂)₂sal ligand, and may affect the crystallization processes. There are antiferromagnetic interactions in the cyclic tetranuclear cobalt(II) compounds 1 and 2. Compound 3 exhibits weak fluorescent emission in the solid state at room temperature.     

Syntheses,crystal structures,and properties of two dinuclear iron(III) complexes constructed with 1,2,3,5-benzenetetracarboxylic acid and chelating N-donor auxiliary coligands

Two dinuclear Fe(III) metal–organic complexes with tetracarboxylate and chelating N-donor ligands, [Fe(Hbtec)(phen)(H₂O)]₂·2H₂O (1) and [Fe(Hbtec)(bpy)(H₂O)]₂·2H₂O (2) (H₄btec = 1,2,3,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) have been prepared and characterized by elemental analysis, IR spectroscopic, and X-ray diffraction methods. Both complexes crystallize in the monoclinic space group P2₁/c with two Fe(III) ions bridged by two Hbtec^3? ligands into a dinuclear unit. Hydrogen bonding connects the dinuclear units into a 3-D framework. The dinuclear units are 10-connected nodes that produce a 3-D framework with topology Schläfli symbol as (3¹²·4²⁸·5⁵). Thermal stabilities and luminescent properties of the two complexes have also been investigated.     

Ligand concentration-dependent supramolecular complexes with uncoordinated carbonyl groups based on a new pyrazole carboxylic acid ligand

One new pyrazole-based ligand, 1-carboxymethyl-3,5-dimethyl-1H-pyrazole-4-carboxylic acid (H₂cmdpca), has been synthesized and characterized. Structural analysis reveals that H₂cmdpca crystallizes in the monoclinic system and adopts a 3-D supramolecular network via the interaction of intermolecular hydrogen bonds. The reactions of Cd(II) ions with H₂cmdpca and 4,4′-bipyridine (4,4′-bpy) afforded three metal complexes, [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)₃]·H₂O (1), [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)]·3H₂O (2), and [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)] (3). Structural analyses reveal that these complexes are all monoclinic and 1, 2, and 3 exhibit mononuclear, 1-D chain, and 1-D with binuclear loop structures, respectively, which are further assembled into 3-D supramolecular frameworks through non-covalent interactions. 1 and 2 are true supramolecular isomers, while 2 and 3 are “pseudo-supramolecular” isomers. In addition, the thermal stability and luminescent properties of the complexes are also investigated.     

Fe(II) and Co(II) pyridinebisimine complexes bearing different substituents on ortho- and para-position of imines: synthesis, characterization and behavior of ethylene polymerization

A series of 2,6-bis(imino)pyridyl iron(II) and cobalt(II) complexes [2,6-(ArNCMe)₂C₅H₃N]MCl₂ (Ar = 2,6-i-Pr₂C₆H₃, M = Fe: 3a, M = Co: 4a; Ar = 2,4,6-i-Pr₃C₆H₂, M = Fe: 3b, M = Co: 4b; Ar = 2,6-i-Pr₂-4-BrC₆H₂, M = Fe: 3c, M = Co: 4c; Ar = 2,4-i-Pr₂-6-BrC₆H₂, M = Fe: 3d, M = Co: 4d) has been synthesized, characterized, and investigated as precatalysts for the polymerization of ethylene in the presence of modified methylaluminoxane (MMAO). The substituents of pyridinebisimine ligands and their positions located significantly influence catalyst activity and polymer property. It is found that the catalytic activities of the iron complexes/MMAO systems are mainly dominated by electronical effect, while those of the cobalt complexes/MMAO systems are primarily controlled by hindering effect.     

The synthesis, using microwave irradiation and characterization of novel, metal-free and metallophthalocyanines

The synthesis of novel metal-free (4) and metallophthalocyanines (5, 6, 7 and 8) were prepared by cyclotetramerization of a novel 4-[2-(1-naphthyloxy)ethoxy]phthalonitrile (3). New substitute phthalocyanines showed the enhanced solubility in organic solvents. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV-Vis and MS spectral data.     

Mononuclear metal complexes of organic carboxylic acid derivatives: synthesis, spectroscopic characterization, thermal investigation and antimicrobial activity

Two Schiff base ligands bearing organic acid moiety, vis., N-(2-thienylmethylidene)-2-amino-4-chlorobenzoic acid (HL(1)) and N-(2-hydroxybenzylidene)-2-amino-4-chlorobenzoic acid (H(2)L(2)) have been synthesized by the interaction of 2-thiophenecarboxaldehyde and 2-hydroxybenzaldehyde with 2-amino-4-chlorobenzoic acid. Co(II), Ni(II), Cu(II) and Zn(II) complexes of these ligands have been prepared. They are characterized on the basis of analytical data, molar conductance, IR, (1)H NMR, UV-vis, mass spectra, magnetic measurements, thermal analysis and X-ray powder diffraction technique. The molar conductance data reveal that these complexes are non-electrolytes. The ligands are coordinated to the metal ions in a terdentate manner with ONO/ONS donor sites of the carbonyl oxygen, azomethine nitrogen and phenolic oxygen or thiophenic sulphur. An octahedral structure is proposed for the prepared metal complexes and some ligand field parameters (D(q), B and beta) in addition to CFSE were calculated. The thermal stability of the metal complexes is evaluated. The Schiff base ligands and their metal complexes have been tested against four species of bacteria as well as four species of fungi and the results have been compared with some known antibiotics.     

Pyrimidine based carboxylic acid terminated aromatic and semiaromatic hyperbranched polyamide-esters: synthesis and characterization

Carboxylic acid terminated aromatic and semiaromatic hyperbranched polyamide-esters (HBPAEs) containing pyrimidine moieties were prepared by polycondensation of 4-hydroxy-2,6-diaminopyrimidine (CBB′) to a double molar ratio of various diacid chlorides (A₂) without any catalyst. The products were soluble in organic solvents, such as N,N-dimethylformamide, N-methyl-2-pyrrolidone and displayed glass transition temperature (T_g) between 180 and 244 °C. The polymerization products have been investigated with FTIR, ¹H and ¹³C NMR analyses and the degree of branching was higher than 60%. Amorphous polymers had inherent viscosity (η_inh) ranging between 0.21-0.28 dL/g and had excellent thermal stability with 10% weight loss at 346-508 °C.     

Kinetic and Thermodynamic Control in Self-Assembly: Sequential Formation of Linear and Circular Helicates

NMR and MS analysis as a function of time has shown that the self-assembly of a linear ligand with Fe²⁺ or Ni²⁺, metal ions of octahedral coordination geometry, generates first a triple helicate and thereafter the circular helicate 1 as kinetic and thermodynamic products, respectively. The results provide insight into features of the energy hypersurface on which this self-assembly operates and point to the general role of kinetic and thermodynamic control in such processes.     

Synthesis,structures, and characterization of copper(II), nickel(II), and cobalt(III) metal complexes derived from an asymmetric bidentate Schiff-base ligand

An asymmetric bidentate Schiff-base ligand (2-hydroxybenzyl-2-furylmethyl)imine (L–OH) was prepared. Three complexes derived from L–OH were synthesized by treating an ethanolic solution of the appropriate ligand with an equimolar amount of metallic salt. Three complexes, Cu₂(L–O^?)₂Cl₂ (1), Ni(L–O^?)₂ (2) and Co(L–O^?)₃ (3), have been structurally characterized through elemental analysis, IR, UV spectra and thermogravimetric analysis. Single crystal X-ray diffraction shows metal ions and ligands reacted with different proportions 1?:?1, 1?:?2 and 1?:?3, respectively, so copper(II), nickel(II), and cobalt(III) have different geometries.     

Syntheses and structural characterization of heterometallic bis(pyrazolyl)methane complexes of rhenium and platinum

The new heterometallic complex {μ-1,3,5-[CH(pz)₂]₃C₆H₃}[Re(CO)₃Br][Pt(p-tolyl)₂]₂ has been prepared by reaction of 1 equiv. of the dimer [Pt(p-tolyl)₂(μ-SEt₂)]₂ with the monometallic rhenium precursor {1,3,5-[CH(pz)₂]₃C₆H₃}Re(CO)₃Br, where 1,3,5-[CH(pz)₂]₃C₆H₃ is the tritopic, arene-linked bis(pyrazolyl)methane ligand 1,3,5-tris[bis(1-pyrazolyl)methyl]benzene. Similarly, the heterometallic complex {μ-1,3,5-[CH(pz)₂]₃C₆H₃}[Re(CO)₃Br]₂[Pt(p-tolyl)₂] has been made by the reaction of the dirhenium compound {μ-1,3,5-[CH(pz)₂]₃C₆H₃}[Re(CO)₃Br]₂ and one-half of an equivalent of [Pt(p-tolyl)₂(μ-SEt₂)]₂. X-ray crystallographic studies of the new compounds reveal significant noncovalent interactions in their molecular and supramolecular structures.     

Synthesis,crystal structures and properties of two Cd(II) complexes based on Zaltoprofen

Abstract

Two metal-organic coordination complexes, [Cd(Zaltoprofen)(phen)]_n (1) and [Cd(Zaltoprofen)(btz)]_n (2) (where Zaltoprofen = 5-(1-carboxyethyl)-2-(phenylthio)phenylacetic acid, phen = 1,10-phenanthroline, btz = thiabendazole), have been synthesized by reaction of Cd(NO₃)₂ with Zaltoprofen, 1,10-phenanthroline or thiabendazole under hydrothermal conditions and characterized by single crystal X-ray diffraction, IR spectra, elemental analyses, powder X-ray diffraction (XRD), electronic spectra (UV-vis) and fluorescent properties. Compound 1 crystallizes in the monoclinic P21/c space group and 2 in the monoclinic system with space group P21/n. [Cd(Zaltoprofen)(phen)]_n (1) features a 1-D zigzag chain. The zigzag chains are linked to form a 2-D layer through π–π stacking interactions. [Cd(Zaltoprofen)(btz)]_n (2) displays a 2D net with alternately arranged left- and right-handed helical chains.     

Three novel lanthanide complexes with imidazole-4,5-dicarboxylate ligand: Hydrothermal syntheses, structural characterization, and properties

Three novel lanthanide complexes, namely, [Ce(Himdc)(H₂imdc)(H₂O)₃]·H₂O (1), {[Dy(Himdc)(Ox)_0.5(H₂O)₂]·H₂O}_n (2), and {[Nd(Himdc)(Ox)_0.5(H₂O)₂]·H₂O}_n (3) (H₃imdc = imidazole-4,5-dicarboxylic acid, Ox = oxalate), have been successfully prepared by the assembly of lanthanide ions and H₃imdc ligand under different synthetic conditions. All of the complexes have been characterized by means of elemental analysis, IR, TG analysis, luminescence spectroscopy as well as single-crystal X-ray diffraction analysis. The 3D supramolecular structure of 1 is constructed from 1D zig-zag chains through the hydrogen bonding interactions. Complex 2 possesses the chair-shaped secondary building units (SBUs) with Dy₆(Himdc)₄(Ox)₂ and meso-helical chains (P + M), resulting in a novel 2D structure based on the linkages of oxalate ligand. Complex 3 also presents 2D layer structure with uninodal 6-connected net topology, but crystallizes in the different space group and owns higher coordination number of the central metal atom than complex 2. The luminescence property of 2 is investigated in the solid state at room temperature.     

Synthesis,characterization and crystal structure of a novel two-dimensional network formed by the reaction of a pyrazole ligand with nickel(II) ions

A new supramolecular complex, [NiCl₂(Hdmpz)₂(H₂O)₂] (Hdmpz = 3,5-dimethylpyrazole), has been synthesized and characterized by elemental analyses, mass spectrometry, conductivity measurements, IR and UV–Vis spectroscopies. The behavior of the complex in different solvents is described. The complex has also been characterized crystallographically: the Ni(II) atom is surrounded by two Cl atoms, two N atoms from Hdmpz and two molecules of water to attain a pseudo octahedral structure. All the ligands are trans-orientated. In this structure, intermolecular interactions have been identified and studied. Extended structure analyses revealed a novel two-dimensional network in the (1 0 0) plane formed by intermolecular O–H···Cl and N–H···Cl hydrogen bonding interactions.     

Crystal structure,thermodynamic behavior,and luminescence properties of a new series of lanthanide halogenated aromatic carboxylic acid complexes

Five lanthanide complexes with polydentate coordination were successfully synthesized by volatilization of 2,4-difluorobenzoate and o-phenanthroline ligands. The structure general formula is [Ln(2,4-DFBA)₃(phen)]₂, (Ln = La(1), Gd(2), Tb(3), Dy(4), Ho(5); 2,4-DFBA = 2,4-difluorobenzoate, phen = o-phenanthroline). The crystal structures of five complexes were determined, and supramolecular structures were probed. Characterization was performed by elemental analysis, IR, Raman spectroscopy and XRD, followed by an examination of the fluorescence and heat capacity properties. The molar heat capacities of complexes 4 and 5 were determined in detail by the DSC apparatus, and the thermodynamic functions were calculated. Finally, the fluorescence properties of complexes 3 and 4 were investigated. Using DFT, the HOMO, LUMO energy levels of the ligands and their single and triplet state energy levels were calculated at the level of the valence layer cleavage 6-311G(d,p) basis group, and the fluorescence enhancement mechanism was explained from the energy transfer perspective.     

Synthesis,structures and characterization of two new supramolecular coordination complexes with the ambidentate ligand 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot)

Two new coordination supramolecular complexes based on a versatile and unsymmetrical 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot) and Mn^II and Ni^II have been synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Reaction of MnCl₂?· 4H₂O with Hpot afforded a neutral mononuclear complex [Mn(pot)₂(H₂O)₄]?·?2H₂O (1), which exhibits a three-dimensional (3-D) supramolecule through versatile intermolecular O–H?···?X (X=O, N and S) hydrogen bond interactions. When using NiCl₂?·?6H₂O instead of MnCl₂?· 4H₂O under similar reaction conditions, a neutral mononuclear complex [Ni(pot)₂(H₂O)₄] (2) is also obtained, which does not exhibit intermolecular hydrogen bonds and π–π stacking interactions. It is very interesting that the pot anion exhibits different coordination modes in complexes 1 and 2. The IR spectra and the TGA for 1 and 2 have been investigated and discussed in detail.     

两种含氮芳香羧酸配合物的水热合成及结构表征

用水热法合成了两种结构新颖的配合物[Cu(PDA)(H2O)2](Ⅰ)和[Ni(PZCA)2(H2O)2](Ⅱ)(H2PDA=2,6-吡啶-二甲酸,HPZCA=2-吡嗪羧酸);利用元素分析、红外光谱和X射线单晶衍射等分析了产物的组成和结构.结果表明,两种配合物均属单斜晶系,空间群均为P21/c,中心离子Cu(Ⅱ)和Ni(Ⅱ)均采取畸变的六配位八面体配位方式;配合物I通过π-π堆积作用和氢键构筑成三维结构,配合物Ⅱ以氢键联接形成二维层状结构.此外,配合物Ⅱ中的PZCA-来自于Ni(Ⅱ)对2,3-吡嗪-二羧酸(H2PZDA)配体的催化脱羧过程.