Crystal Structure of a Nickel(II) Complex with Asymmetric _L-Histidine Ligand

1 INTRODUCTION Metal-amino acid complexes are involved in the process of some important metal transport in humans. These complexes and their derivatives are important due to their biochemical and pharmacological pro- perties[1～5]. Nickel(II), as a Jahn-Teller center, when complexed with amino acids, adopts a variety of coordination geometries from distorted square plane, flattened tetrahedron and distorted square pyramid to distorted octahedron as observed in structures reported[6, 7], …     

Nickel(II) thiosemicarbazone complex catalyzed Mizoroki–Heck reaction

Convenient synthesis of a new square planar nickel(II) naphthaldehyde thiosemicarbazone complex has been described. The composition of the complex has been established by elemental analysis, spectral methods, and single crystal X-ray crystallography. The new complex acts as an active homogeneous catalyst for the Mizoroki–Heck reaction of electron deficient (activating) and electron rich (deactivating) aryl bromides with various olefins under optimized conditions.     

Crystal Structure and Characterization of 2-N-(2-Hydroxy-benzylidene) Furanmethanoamine Nickel(II) Complex

1 INTRODUCTION Recently, the low-spin square-planar nickel(II) complexes and high-spin octahedral nickel(II) complexes with Schiff base ligands have received much attention in optical materials[1～3]. Some nic- kel(II) complexes are widely used as lubricating oil, rubber industry additives, a fire-resistant additive and fungicide for leather[4～7]. Also, their adducts with nitrogen have attracted broad attention due to their potential applications as organic conductors and magnetic mate…     

Crystal Structure of a Nickel(Ⅱ) Complex with Asymmetric L-Histidine Ligand

A novel nickel(Ⅱ) complex with L-histidine has been synthesized and solved by single-crystal X-ray diffraction analysis at physiological pH. The title complex (C7H16NiN4O6S, Mr= 343.01) crystallizes in monoclinic, space group P21 with a = 7.2194(7), b = 7.5968(7), c =12.2797(11) (A), β = 93.3110(10)°, V = 672.35(11) (A)3, Z = 2, Dc= 1.694 g/cm3, F(000) = 356,μ(MoKα) = 1.626 mm-1, T = 293(2) K, the final R = 0.0184 and wR = 0.0426 for 2207 observed reflections with I ＞ 2σ(Ⅰ). The complex provides insights into a possible structural arrangement between nickel (Ⅱ) and L-histidine which may be physiologically important and abundantly present in biological systems.     

Synthesis, Crystal Structure and Thermal Stability of (Diacetylacetone)(diimidazole)Nickel(II) Complex

1 INTRODUCTION Acetylacetone is well known as the intermediate product of organic synthesis reaction, which can be used as annexing agent in gasoline, lubricant and desiccant in paint. Also it has been found to possess fungicidal and insecticidal activi…     

Off-on-off Luminescent Switching of a Novel Ru(II) Complex

There has been explosive interest in the synthesis and applications of novel Ru(II) polypyridyl complexes with respect to molecular sensors1,2, switches3, and sensitizers of Gr鋞zel solar cells based on nanocrystalline TiO24. Here we report a novel Ru(II) complex, which can serve as pH-induced remarkable off-on-off luminescent switch. Scheme 1 The acid-base equilibria of the complex UV-vis absorption and emission spectroscopic pH titration experiments of the Ru complex wit…     

Synthesis and Crystal Structure of a New Ternary Complex of Nickel(II) with L-Aspartic Acid and 1,10-Phenanthroline

1 INTRODUCTION Amino acid is the fundamental structure unit ofbiomacromolecules, such as protein and enzyme, andit is also the important biomicromolecular ligandinside the life body. Study on the metal-amino acidcomplex is the basis of understanding …     

Synthesis,Structure and Magnetic Property of a Binuclear Nickel(Ⅱ) Complex

A new binuclear complex [Ni2(2,2'-bpy)2(C8H3NO6)2(H2O)4] 1 (2,2'-bpy = 2,2'- bipyridine, C8H3NO6 = 4-nitrophthalate) has been synthesized by a hydrothermal reaction and characterized by X-ray single-crystal diffraction analysis. The complex crystallizes in triclinic, space group P1 with a = 7.206(2), b = 10.337(4), c = 12.480(4) , α = 89.887(11), β = 77.033(9), γ = 78.349(6)o, V = 886.3(5) 3, Z = 1, C36H30Ni2N6O16, Mr = 920.08, Dc = 1.724 g cm-3, F(000) = 472, μ = 1.152 mm-1, the final R = 0.0458 and wR = 0.1163 for 3372 observed reflections with I 2σ(Ⅰ). The two Ni(Ⅱ) ions are bridged by two 4-nitrophthalates both in a bis-monodentate mode. Magnetic measurements reveal that the intramolecular exchange couplings in the dimer are ferromagnetic with 2J/k = 2.32 K, D =-1.44 K and g = 2.18.     

Nickel(II) and palladium(II) thiaethyneporphyrins. Intramolecular metal(II)-η2-CC interaction inside a porphyrinoid frame

3,18-Diphenyl-8,13-di-p-tolyl-20-thiaethyneporphyrin ([18]thiatriphyrin(4.1.1)), which formally contains an C1-C2 ethyne moiety instead of pyrrole embedded in the macrocyclic framework of 21-thiaporphyrin, was obtained in a modification of the "3 + 1" approach using the ethyne analogue of tripyrrane (1,4-diphenyl-1,4-di(pyrrol-2-yl)but-2-yne) and 2,5-bis(p-tolylhydroxymethyl)thiophene. The spectroscopic and structural properties of 20-thiaethyneporphyrin reflect its macrocyclic aromaticity, revealing a combination of the acetylene (≥C-C≡C-C≤) and cumulene (>C═C═C═C<) character of the C18-C1-C2-C3 linker. The magnetic manifestations of aromaticity and antiaromaticity of thiaethyneporphyrin and its two-electron-oxidized derivative were observed using (1)H NMR spectroscopy and were confirmed by density functional theory calculations involving chemical shifts and nucleus-independent chemical shift analysis. Protonation of 20-thiaethyneporphyrin yielded a nonaromatic tautomer of iso-20-thiaethyneporphyrin, locating the saturated meso carbon adjacent to thiophene. Insertion of palladium(II) and nickel(II) into 20-thiaethyneporphyrin afforded planar palladium(II) thiaethyneporphyrin and low-spin diamagnetic nickel(II) 20-thiaethyneporphyrin as determined by X-ray crystallography. 20-Thiaethyneporphyrin acts as a dianionic ligand that coordinates through the two nitrogen and one sulfur donors. Metal(II) ions are uniquely exposed to form an intramolecular metal(II)-η(2)-CC bond, whereas the organometallic fragment is coplanar with the whole macrocycle. Coordination of pyridine converts diamagnetic nickel(II) thiaethyneporphyrin into its paramagnetic counterpart as determined by (1)H NMR.     

Soft template synthesis in copper(II)–dithiooxamide–methanal,copper(II)–dithiooxamide–ethanal and copper(II)–dithiooxamide–propanone triple systems in a copper(II)hexacyanoferrate(II) gelatin-immobilized matrix

Novel complexing processes in the Cu^II–dithiooxamide–methanal, Cu^II–dithiooxamide–ethanal and Cu^II–dithiooxamide–propanone triple systems proceeding under specific conditions, to copper(II)hexacyanoferrate(II) gelatin-immobilized matrix systems in contact with aqueous-alkaline (pH 12) solutions containing dithiooxamide and methanal, ethanal or propanone, have been studied. It has been shown that template synthesis leading to the formation of macrocyclic coordination compounds (2,8-dithio-3,7-diaza-5-oxanonandithioamide-1,9)copper(II), (2,8-dithio-3,7-diaza-4,6-dimethyl-5-oxanonandithio-amide-1,9)copper(II) and (4,4,6-trimethyl-2,8-dithio-3,7-diazanonen-6-dithioamide-1,9)copper(II), respectively, takes place under such conditions. Dithiooxamide, methanal, ethanal and propanone act as ligand synthons in these processes.     

Synthesis, Crystal Structure and Cytotoxic Activity of a Novel Nickel(II) Complex with Schiff Base Derived from Salicylhydrazide

A novel Schiff base complex with π-conjugated system, [Ni(L1)2(py)2] 1 (L1 = (E)-N'-(2,4-dichlorobenzylidene)-2-oxidobenzohydraizide), was synthesized and characterized by elemental analysis and single-crystal X-ray determination. Complex 1 crystallizes in the monoclinic system, space group P21/n with a = 12.8286(10), b = 16.3573(13), c = 19.0206(14) , β = 108.2920(10)o, V = 3789.6(5) 3, Z = 4, Mr = 833.17, Dc = 1.460 g/cm3, μ = 0.843 mm-1, F(000) = 1704, the final R = 0.0537 and wR = 0.0640 for 3836 observed reflections with I > 2σ(I). In the molecular structure of 1, the NiII atoms are six-coordinated by two N and two O atoms from two Schiff base ligands (L1) and two N atoms from two pyridine solvent molecules to form a distorted octahedral geometry. The cytotoxic activities of complex 1 have been experimentally studied against a human HeLa cell in vitro.     

Copper(II)–8-mercaptoquinoline,copper(II)–5,8-dimercaptoquinoline and copper(II)–5-thiomethyl-8-mercaptoquinoline complexing in a copper(II)hexacyanoferrate(II) gelatin-immobilized matrix

Novel complexing processes in the Cu^II–8-mercaptoquinoline, Cu^II–5,8-dimercaptoquinoline and Cu^II–5-thiomethyl-8-mercaptoquinoline systems proceeding in the copper(II)hexacyanoferrate(II) gelatin-immobilized matrix in contact with aqueous solutions of the ligands indicated, have been studied. Under the conditions specified for complexing in the Cu^II–8-mercaptoquinoline system, only a monomeric water-insoluble coordination compound was formed. In the Cu^II–5,8-dimercaptoquinoline system, three coordination compounds were formed and, in the Cu^II–5-thiomethyl-8-mercaptoquinoline system, two such compounds were formed. Conversely, complexing in solution or solid phase results in the formation only coordination compounds in each of the system studied.     

Ar-BINMOL–Derived Salan–Cu(II) Complex–Catalyzed Silyl-Reformatsky Reaction of Aromatic Aldehydes

In this work, we have developed a facile protocol with salan–Cu system for the facile and selective synthesis of β-hydroxyesters via silyl-Reformatsky reaction with α-silylester and aldehydes. The screening and optimization of reaction conditions led to the determination of a practical and efficient procedure in which the salan–Cu exhibited promising catalytic activity in dimethylsulfoxide, in which the silyl-Reformatsky reaction of aromatic aldehydes with α-trimethylsilylmethylacetate gave the corresponding β-hydroxyester derivatives in excellent yields (up to 98%) under fluoride-free reaction conditions.     

Heterospin Copper(II) Catecholate Complex with the TEMPO–Iminopyridine Ligand

Russian Journal of Coordination Chemistry - The heterospin copper(II) complex, ((pyridin-2-ylmethylene)-4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl)-3,6-di-tert-butylcatecholatocopper(II) (I), is...     

Air-Stable Cobalt(II) and Nickel(II) Complexes with Schiff Base Ligand for Catalyzing Suzuki–Miyaura Cross-Coupling Reaction

The Co(II) complex [Co{C₆H₄–1,2-(N=CH–C₆H₄O)₂}] (I) and Ni(II) complex [Ni{C₆H₄–1,2-(N=CH–C₆H₄O)2}] (II) with Schiff base of o-phenylenediamine and salicylaldehyde have been synthesized. The structure of the ligand and its complexes were derived on the basis of various techniques such as elemental analysis, mass, FT-IR, electronic spectra and magnetic susceptibility. From the Singal crystal X-ray diffraction (SCXRD) analysis techniques (CIF file CCDC no. 1498772 (II)), it has been confirmed that the Schiff base ligand (L), coordinates to the metal ion in a tetradentate fashion through the nitrogen and oxygen atom. In addition, the square planar geometry of Ni(II) complex also has been confirmed from SCXRD. Electronic spectra, mass spectra, and magnetic susceptibility measurements reveal square planar geometry for the Co(II) complex. Synthesized complexes were used in cross-coupling of arylhalides with phenylboronic acid. The transformation offers products in good yields using 0.02 mmol catalysts loading, thereby proving the efficiency of the complexes as catalysts for Suzuki–Miyaura reaction.     

Electrochemical Reduction of Nickel(II)—Dihydroxyanthraquinone Sulfonate: How Complex Formation Affects Biochemical Behavior?

Electrochemical behavior of the Ni^II complex of sodium 1,4-dihydroxy-9,10-anthraquinone-2-sulfonate Na₂[Ni^II(LHSO₃)₂Cl₂] · 2H₂O was studied by cyclic voltammetry in non-aqueous and aqueous buffer. The aim of the present work was to understand the behavior of the semiquinone radical anion formed after reduction of the free quinone centre of a ligand for which the other quinone centre binds a metal ion (Ni^II), not having a stable low oxidation state. In dimethylformamide solution an additional reduction peak appeared at a much more negative potential due to adsorption. The complex Na₂[Ni^II(LHSO₃)₂Cl₂] · 2H₂O undergoes diffusion controlled one-electron reduction unlike the two-electron reduction observed for most hydroxy-9,10-anthraquinones inspite of having two quinone centres in the complex (one on each ligand). In aqueous media a kinetic effect was observed during electron transfer at the electrode surface. The values of the electron transfer rate constants during the reduction of the complex at the electrode were evaluated and found to be dependent on the scan rate. Electrochemical behavior of the chosen hydroxy-9,10-anthraquinone (NaLH₂SO₃) was significantly modified in the complex with quinone. This result is important for biochemical studies, since NaLH₂SO₃ resembles the core moiety of anthracycline antitumor drugs. Several studies have reported that in case of anthracyclines complexation can help to reduce the formation of semiquinone moieties, leading to a lesser generation of superoxide responsible for drug’s cardiotoxicity. The electrochemical behavior of the title complex actually justifies such claims and tries to explain why a reduction in semiquinone formation helps to decrease the formation of superoxide.     

Ethylene Oligomerization Catalyzed by Nickel(II) Diimine Complexes

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Nickel(II) and copper(II) – l-cysteine,l-methionine,l-tryptophan-nucleotide ternary complexes

Four new ternary complexes of Cu^II with l-methionine and the nucleotides 5AMP (adenosine 5-phosphate), 5GMP (guanosine 5-phosphate) and 5IMP (inosine 5-phosphate), and with l-tryptophan and 5AMP, were synthesized and characterized by elemental analysis and i.r. spectroscopy. One ternary complex of N^II with l-cysteine and 5IMP was also prepared and characterized. The study of the three ternary compounds of Cu^II, of general formulae Cu-5NMP-l-methionine, indicates coordination of the phosphate group and of N(7) of the purinic ring. l-Methionine is bound by the carboxylic and amino groups. The ternary complex obtained from a mixture of Cu-5AMP and l-tryptophan is a dimer in which the nucleotide bridges the two copper atoms. In the complex of Ni-5IMP and l-cysteine, the nucleotide seems to bind the metal through the N(7) of the heterocyclic ring, and the l-cysteine is coordinated as a bidentate chelate by the carboxyl and thiol groups. E.s.r. spectra of the copper complexes are in good agreement with the low symmetry structure proposed. The one-electron reduction potentials E_c(Fc⁺/Fc) (V) of Cu^II to Cu^I were established for the four copper complexes from cyclic voltammetry studies. The one-electron oxidation potential E_a(Fc⁺/Fc⁺) (V) of Ni^II to Ni^III was also measured for the nickel complex.     

Synthesis and Structural Characterization of a New Cadmium(II) Complex with a Double Betaine

1 INTRODUCTION The construction of supramolecular aggregates has received much attention due to their intriguing network topologies and potential functions as new classes of materials[1, 2]. Multiple noncovalent interac- tions, such as hydrogen bonds, π-π stacking and host- guest ionic interactions, play important roles in the supramolecular assembly of metal ions and organic ligands[3, 4]. In this context the multidentate ligands with conjugated groups are employed as building blocks in…