Self-assembly of hydrogen-bonded supramolecular structures of two copper(II) 2-bromobenzoate complexes with 4-pyridylmethanol and nicotinamide

The structures of [Cu(2-Brbz)₂(4PM)₂(H₂O)] (1) and [Cu(2-Brbz)₂(NIA)2] · 2H₂O 2 [where 2-Brbz is the 2-bromobenzoate anion, 4-PM is the 4-pyridylmethanol and NIA is nicotinamide] have been determined by X-ray and characterized by EPR spectroscopy. The Cu²⁺ cation in 1 is coordinated by a pair of oxygens from monodentate 2-bromobenzoate anions by a pair of pyridine nitrogens from monodentate 4-pyridylmethanol ligands and finally by a water forming a tetragonal-pyramidal coordination polyhedron. The Cu²⁺ cation in 2 is coordinated by two pairs of oxygens from the asymmetric bidentate 2-bromobenzoate anions and by a pair of pyridine nitrogen atoms from the monodentate nicotinamide in trans positions, forming an extremely elongated bipyramid. The molecules of both complexes are linked by O–H ··· O, C–H ··· O and for 2 by N–H ··· O hydrogen bonds, which create three-dimensional hydrogen-bonding networks. EPR spectra of 1 and 2 are in agreement with X-ray data. Nicotinamide as well as 4-pyridylmethanol are suitable ligands for construction of hydrogen bonding coordination polymers.     

Synthesis and characterization of three ionic pairs of Fe(II) and Co(II) complexes with tridentate salicylideneglycine

Three new transition metal complexes, [Fe^II(H₂O)₆][(C₉H₇NO₃)₂Fe^II] · H₂O (1), H[K(H₂O)₃][(C₉H₇NO₃)₂Co^II] · H₂O (2), and [Co^II(H₂O)₆][(C₉H₇NO₃)₂Co^II] · H₂O (3), with salicylideneglycine have been synthesized and characterized by elemental analysis, IR spectra, UV-Vis spectroscopy, and X-ray crystallography. The structure analyses indicate that the tridentate salicylideneglycine binds through aliphatic nitrogen, phenoxy, and carboxylic oxygen in the anion. There are many inter- and intra-molecular hydrogen bonds among lattice water, the anion, and the cation to form a 3-D network. The thermogravimetric analyses and the quantum chemistry calculations of compounds 1, 2, and 3 are also discussed.     

Three new pyridine-2,6-dicarboxylate copper(II) compounds with coordinated pyridine-based ligands: Synthesis, characterisation and crystal structures

Three new Cu(II) compounds of pyridine-2,6-dicarboxylic acid (H₂pdc) with meta-substituted pyridines as additional ligands have been synthesized and structurally characterised using X-ray diffraction. Two of them are mononuclear compounds, i.e. [Cu(pdc)(3acpyr)(H₂O)] (1) (3acpyr = 3-acetylpyridine) and [Cu(pdc)(3HOp)(H₂O)](H₂O)₂ (2) (3HOp = 3-hydroxypyridine). The third compound is polynuclear, i.e. [Cu(pdc)(μ-3HOmp-κN,O)]_n (3) (3HOmp = 3-(hydroxymethyl)pyridine). The three compounds are also characterised by IR, EPR and ligand field spectroscopy. The geometry around the Cu(II) ions is distorted square pyramidal for compounds 1 and 2 and distorted octahedral for compound 3. The lattice of compound 1 is organised by an intra-sheet hydrogen-bond pattern generating double layers. Compound 2 has a lattice arranged by the two water molecules in the lattice with complicated 2D O-H?O intra-sheet hydrogen bonding motifs.The zig-zag chains in compound 3 are further organised in layers, due to the axial coordination at Cu(II), forming a so-called (4, 3) ladder-like one-dimensional coordination polymer. These ladders are interconnected by hydrogen bonding.     

Diversity of supramolecular aggregation in copper(II) pentane-2,4-dionato compounds with methyl substituted 2-aminopyridines

Three copper(II) bis(pentane-2,4-dionato-κ ² O,O′) compounds with 2-amino-3-methylpyridine (2,3-ampy) (1), 2-amino-5-methylpyridine (2,5-ampy) (2), and 2-amino-4-methylpyridine (2,4-ampy) (3) were prepared by reaction of bis(pentane-2,4-dionato-κ ² O,O′)copper(II) with selected methyl substituted 2-aminopyridines. The coordination of Cu(II) in all three compounds is square pyramidal and intramolecular N–H?···?O hydrogen-bonding is present. X-ray crystallographic studies reveal different crystal aggregation influenced by a methyl substituent on pyridine. No intermolecular N–H?···?O hydrogen-bonding is present in 1. Intermolecular N–H?···?O hydrogen-bonding in 2 forms infinite chains and dimers are formed in 3. Extended 3-D aggregation was found in 2 via π–π and C–H?···?π (arene) interactions, while only chain formation was found in 1 and 3.     

Structure and magnetic properties of a double out-of-plane carboxylato-bridged Cu(II) compound with pyridine-2-carboxylate

The spectroscopic and magnetic properties, and crystal structure of dark-blue [Cu(2-pca)₂]_n (1), (2-pca = pyridine-2-carboxylate ion) are described. The copper(II) ions are in strongly tetragonally distorted octahedral environments. They are sequentially bridged by a double out-of-plane carboxylate bridge, resulting in the formation of an infinite chain (1D). The equatorial Cu–O bonds (1.957(3) Å) are significantly shorter than the axial bonds (2.737(4) Å). The crystal structure of the compound is stabilized by interchain hydrogen bonds of the C–H?O type. The intrachain copper–copper separation is 5.178(3) Å, whereas the shortest interchain copper–copper distance is 7.614(6) Å. The magnetic properties, investigated in the temperature range 1.8–300 K, revealed the occurrence of a weak intrachain antiferromagnetic coupling, J = −1.04 cm⁻¹, and an interchain exchange interaction, zJ′ = 0.34 cm⁻¹. The title compound appears to be a polymorphic form of the blue-violet compound (2) of identical stoichiometry, the X-ray structure of which was recently reported. Magneto-structural correlations in 1 have been made considering both the carboxylato bridging group and the existence of interchain hydrogen bonds. The structure and magnetic properties of 1 are compared with those of the polymorphic form 2.     

Extended chains via hydrogen bond linkages of dinuclear copper(II) and cadmium(II) complexes with a new flexible disulfoxide ligand

A new flexible disulfoxide ligand 1,6-bis(benzylsulfinyl)hexane (L), which is a mixture of the meso and rac isomers, was treated with Cu^II or Cd^II nitrate and obtained dimeric complex [Cu₂(L)₃(H₂O)₂(NO₃)₄] 2 or [Cd₂(L)₃(H₂O)₂(NO₃)₄] 3. In the reacting system the crystals of meso isomer 1 of L together with 2 or 3 were obtained. 2 and 3 have similar molecular structures. In the neutral dimer, three ligands present two kinds of coordination models: monodentate and bis-monodentate. The neutral dimeric units in 2 and 3 are linked by hydrogen bonds to yield a chain structure. Crystal structures of all three compounds were determined by single-crystal X-ray diffraction methods. Crystal data for 1: monoclinic, space group Cc, a=41.95(2), b=5.132(2), c=8.660(4) Å, β=94.898(9)°, V=1857.7(15) Å³, Z=4, final refinement (I>2σ(I)): R1=0.0659, wR2=0.1415. Crystal data for 2: triclinic, space group P-1, a=9.242(4), b=9.539(4), c=21.042(9) Å, α=83.888(9), β=87.971(8), γ=74.177(9)°, V=1774.6(13) Å³, Z=2, final refinement (I>2σ(I)): R1=0.0577, wR2=0.0954. Crystal data for 3: triclinic, space group P-1, a=9.203(4), b=9.831(3), c=20.860(7) Å, α=84.313(6), β=86.432(7), γ=74.188(6)°, V=1805.9(11) Å³, Z=2, final refinement (I>2σ(I)): R1=0.0548, wR2=0.1192.     

Synthesis and structures of cadmium(II) complexes of a series of multinucleating N/S donor ligands

The coordination chemistry of a series of bis-bidentate ligands with cadmium(II) ions has been investigated. The ligands, containing two N,S-donor chelating (pyrazolyl/thioether) fragments, have afforded complexes of a variety of structural types (dinuclear M₂L₂ ‘mesocate’ complexes, a one-dimensional chain coordination polymer and a simple mononuclear complex) according to whether the bis-bidentate ligands act as bridges spanning two metal ions, or a tetradentate chelate to a single metal ion. The p-phenylene and m-biphenyl spaced ligands L¹ and L³ form dinuclear M₂L₂ complexes where the ligands are arranged in a ‘side-by-side’ fashion. In contrast the m-phenylene spaced ligand L² forms a one-dimensional coordination polymer where the ligands adopt a highly folded conformation. The 1,8-naphthalene spaced ligand L⁴ adopts a tetradendate chelating mode and affords a simple mononuclear complex.     

Polynuclear Cu(II), Ni(II) and Cd(II) coordination compounds with bis(pyrimidin-2-yl)amine and dicyanamide

In this study the synthesis, crystal structure and characterization of three new transition metal polynuclear compounds with formula [Cu(dipm)(μ-dca)₂]_n(H₂O) (1), [Ni(dipm)(μ-dca)₂]_n(C₂H₆O)_1/2 (2) and [Cd(dipm)(μ-dca)₂]_n (3) (in which dipm = bis(pyrimidin-2-yl)amine and dca = dicyanamide) are reported. The isostructural compounds 1 and 2 contain a double-bridging end-to-end dca unit connecting two metal ions and a single bridging end-to-end dca unit between subsequent metals. Compound 3 exhibits only single bridging end-to-end dca units, oriented in three directions, giving rise to a 3D framework.     

Syntheses and crystal structures of two Cu(II) complexes based on a fused heterocycle ligand containing 1,3,4-thiadiazole

By refluxing a mixture of CuCl₂ and 3-methyl-6-phenyl-[1,2,4]-triazolo[3,4-b][1,3,4]thiadiazole (TRTZ) with addition of acetic acid and KSCN, respectively, the complexes [Cu(TRTZ)₂(OAc)₂(H₂O)]?·?1.5H₂O (1) and [Cu(TRTZ)₂(SCN)₂(H₂O)₂]?·?2DMF (2) were obtained. Single-crystal structure of both complexes was determined and their thermal behaviour and IR spectra examined.     

A new oxamido-bridged dinuclear copper(II) complex with large antiferromagnetic exchange interactions

A new oxamido-bridged dinuclear compound [Cu₂(µ-pmox)(DMF)₄]?·?2ClO₄ (1) (H₂pmox?=?N,N′-bis-(2-methylpyridyl)oxalamide, DMF?=?dimethylformamide) was synthesized and structurally characterized. The five-coordinate Cu(II) is bridged by oxamido groups and further cross-linked by C–H···O hydrogen bonds between the uncoordinated oxygen of perchlorate and methyl of DMF. The complex was also characterized by infrared spectroscopy and magnetic measurement. The copper complex exhibits strong antiferromagnetic interactions via the trans oxamido bridge with J of ?414?cm^?1, where J is the exchange parameter in the isotropic Hamiltonian H?=??JS₁S₂.     

Synthesis,crystal structure,redox behavior and DNA-binding properties of a series of copper(II) complexes with two new carboxamide derivatives

Four mononuclear copper(II) complexes of two new carboxamide derivatives formulated as [Cu(L¹)₂](ClO₄)₂ (1a), [Cu(L¹)₂](NO₃)₂ (1b), [Cu(L²)₂(H₂O)₂](ClO₄)₂ (2a), and [Cu(L²)₂(H₂O)](NO₃)₂ (2b) have been isolated in pure form from the reaction of L¹ and L² [where L¹ = N-(furan-2-ylmethyl)-2-pyridinecarboxamide and L² = N-(thiophen-2-ylmethyl)-2-pyridinecarboxamide] with copper(II) salts of perchlorate and nitrate. All the complexes were characterized by physicochemical and spectroscopic tools along with single-crystal X-ray diffraction studies. The structural analyses showed that 1 is monomeric of square planar geometry with copper(II) chelated by two L¹ ligands. Complex 2 differs in coordination geometry, being octahedral and distorted square pyramidal. Two L² ligands occupy the equatorial positions of the octahedral 2a and the basal sites of the pyramidal 2b, with water molecules that complete the coordination sphere in each case. Electrochemical studies using cyclic voltammetry showed a reversible redox behavior of the copper(II) in 1 and 2. The electronic spectroscopic behavior and the trend of one electron equivalent redox potential corresponding to a Cu^II/Cu^I couple have also been confirmed by density functional theory calculations. The spectroscopic and viscosity measurement study in tris–HCl buffer suggested an intercalative interaction of 1a and 2 with calf thymus DNA likely due to the stacking between the non-coordinated furan and thiophene chromophore with the base pairs of DNA.     

Synthesis and structural characterization of copper(II), cadmium(II) and zinc(II) complexes with 4,5-diazaspirobifluorene and bis-9-biphenyl-4,5-diazafluorenyl peroxide

The synthesis and structural chemistry of four new divalent transition metal complexes of the fluorene ligands 4,5-diazaspirobifluorene (L1) and bis-9-biphenyl-4,5-diazafluorenyl peroxide (L2), [Cu₃(L1)₄(NO₃)₆(H₂O)₂] · 2CH₃CN (1), [Cu(L1)(CH₃CO₂)₂(H₂O)] · 2H₂O (2), [Cd(L1)₂(NO₃)₂] · DMF (3) (DMF = N,N-dimethylformamide) and [Zn₂(L2)(μ-Cl)₂Cl₂]_∞ (4) are described. Single-crystal X-ray diffraction analysis reveal that the four complexes exhibit various frameworks due to diverse coordination modes and different conformations of ligands L1 or L2, as well as nitrate, acetate or chloro counterions. L1 in complexes 1, 2 and 3 present an asymmetric rigid bidentate ligand with two nitrogen atoms as the donor sites. Novel complex 4 was formed through complexation between conformationally bent shaped peroxide ligands and zinc(II) dichlorides that adopt a linear coordination geometry, which can also give rise to extended polymeric chains with a zigzag secondary structure.     

Bis-(bis-(1,3-diaminopropane)-copper(II) Tetracyanonickellate(II)) Tetrahydrate: Preparation, Characterization, and Crystal Structure of a Novel Molecular Tetracyanonickellate

Summary.  [Cu(tn)₂Ni(CN)₄]₂ċ4H₂O and Cu(tn)₂Ni(CN)₄ (tn = 1,3-diaminopropane) were prepared and characterized. The hydrate is unstable on air and readily dehydrates to Cu(tn)₂Ni(CN)₄. Crystal structure analysis of the hydrate at 150 K revealed a novel tetranuclear molecular structure of the tetracyanonickellate. The building elements are two [Cu(tn)₂]²⁺ cations (coordination numbers of Cu: 5 and 6, respectively), two [Ni(CN)₄)²⁻ anions, and crystal water. The two cations are linked by one tetracyanonickellate anion via bridging cyano groups placed in cis positions. The second anion is bound weakly (Cu-N = 2.82 ?) via one μ₂-bridging cyano ligand. The tetranuclear molecules and pairs of solvate water molecules are linked by strong hydrogen bonds, thus forming infinite planes which are linked in the third dimension by considerably weaker hydrogen bonds. Received May 9, 2000. Accepted (revised) August 21, 2000     

Self-assembly and crystal structure of a three-dimensional copper(II) complex

A copper(II) complex of a sulfonate derivative of chrysin, 5,7-bihydroxyflavone-6-sulfonate, Cu(C₁₅H₈O₇S)(3H₂O), has been prepared. The complex was characterized by elemental analysis, spectroscopic measurements and single-crystal X-ray diffraction studies. It crystallizes in the monoclinic space group C2/c, with a?=?16.036(18), b?=?6.944(8), c?=?28.03(3)?Å, β?=?94.463(17)°, V?=?3112(6)?ų, Z?=?8. In the complex, Cu(II) is five-coordinate and all donors are oxygen atoms. Hydrogen bonds and π–π stacking interactions in the crystal lead to the formation of a three-dimensional supramolecular motif.     

Kristallzucht und Strukturverfeinerung von Quecksilber(II)‐amidchlorid – HgClNH2

Crystal Growth and Refinement of the Crystal Structure of Mercury(II) Amide Chloride – HgClNH₂ Single crystals were prepared by recrystallization of HgClNH₂ from aqueous NH₃/NH₄⁺ solution at 160 °C. They were used for a single‐crystal X‐ray structure redetermination. The previously reported [W. N. Lipscomb, Acta. Crystallogr. 1951 , 4, 266.] structural topology determined on basis of X‐ray powder diffraction data is now confirmed. However, a higher symmetry is found: Space group type Pmma (instead of Pmm2), a = 6.709(1) Å, b = 4.351(1) Å, c = 5.154(1) Å, Z = 2. The crystal structure contains zig‐zag‐chains [Hg(NH₂)_2/2]⁺. Four Cl atoms complete the coordination sphere of Hg to a distorted octahedron. These share common faces and edges in layers [HgCl_4/4(NH₂)_2/2]. These layers are connected via hydrogen bonds N–H…Cl.     

Structures of substituted di-aryl-1,3,4-oxadiazole derivatives: 2,5-bis(pyridyl)- and 2,5-bis(aminophenyl)-substitution

Crystal structures of four different di-aryl-1,3,4-oxadiazole compounds (aryl = 2-pyridyl-, 3-pyridyl-, 2-aminophenyl-, 3-aminophenyl-) are determined. Crystallization of di(2-pyridyl)-1,3,4-oxadiazole yielded monoclinic and triclinic polymorphs. The structures are characterized by the occurrence of π–π interactions. Additionally, in case of the aminophenyl compounds intra- as well as intermolecular hydrogen bonds are found that influence the packing motif as well. Since these molecules are often used as ligands in metal–organic complexes similarities and differences of the molecular conformation between the molecules in the pure crystals and that of the ligands in the complexes are discussed.     

Synthesis,structure and antimicrobial study of two new copper(II) complexes derived from N-(3-aminopropyl) benzylamine ligand (apba) and N-salicylidene-apba

Two new copper(II) complexes were synthesized by reaction of N-(3-aminopropyl)benzylamine (L1: apba, for complex 1) and N-salicylidene-apba (L2: for complex 2) with Cu²⁺. Crystals of complex 1 were orthorhombic, space group pccn, with a?=?15.2149(10), b?=?25.0071(16), c?=?7.6280(5)?Å and α?=?β?=?γ?=?90°. Complex 2 crystals were monoclinic, space group P2₁/c, with a?=?8.688(6), b?=?12.812(9), c?=?16.022(11)?Å and β?=?99.241(10)°. Structures of the two complexes were centro-symmetric and both Cu(II) atoms were four coordinate with a distorted square-planar geometry. The toxicity of the complexes was evaluated by testing antimicrobial activity against bacterial strands.     

A systematic study of ligand intermolecular interactions in crystals of copper(II) complexes of bidentate guanidino derivatives

The synthesis and X-ray structures of four neutral copper(II) complexes and one cationic complex incorporating bidentate alkyl N-(4-oxo-5,5-diphenyl-4,5-dihydro-1H-imidazol-2-yl)imidocarbamate ligands are reported. The neutral complexes, which possess potential doublet (DA) hydrogen bonding motifs, form supramolecular structures based on synthons involving hydrogen bonding or phenyl embraces. The formation of sheets within the crystal through combination of these synthons, and the occurrence of guest molecules trapped in cavities between the sheets, are described. The cationic complex forms an extended hydrogen-bonded structure that incorporates nitrate ions. The structures of the five complexes are compared with others reported previously for complexes of related ligands.     

Structural characterization of five-coordinate copper(II), nickel(II), and cobalt(II) thiocyanato complexes derived from bis(2-(3,5-dimethyl-1-pyrazolyl)ethyl)amine

The reaction of M(ClO₄)₂·6H₂O with NH₄NCS in presence of the organic sterically hindered bis(2-(di-3,5-dimethyl-1-pyrazolyl)ethyl)amine (bedmpza) afforded the five-coordinate mononuclear dithiocyanato-M(II) complexes [M(bedmpza)(NCS)₂]·xMeOH (1: M = Cu²⁺, x = 0; 2: M = Ni²⁺, x = 0; 3: M = Co²⁺, x = 0.84). The compounds which proved to be non-electrolytes were characterized by IR and UV-Vis spectroscopy and their molecular structures were determined by single-crystal X-ray crystallography. In these complexes, the five-coordinate geometry was achieved by the three N-donors of the ligand bedmpza and two N atoms of the terminal thiocyanato ligands. The Cu(II) complex exists in two polymorphs 1-I and 1-II: an intermediate five-coordinate geometry with the two thiocyanato ligands are arranged as cisoid in 1-I and distorted square pyramidal geometry with the thiocyanato ligands are in transoid orientation in 1-II. Although the later geometry was also observed in the nickel complex 2, distorted trigonal bipyramidal geometry was found in 3. Each complex forms hydrogen bonds of type N-H?S from the secondary amine N(3) donor atoms to the adjacent terminal S(1) acceptor atoms of the thiocyanate group. The thermal behavior of the two polymorphs 1-I and 1-II were similar and no significant differences were observed between the two complexes.