Trinuclear Nickel Research Articles

A Trinuclear Nickel(II) Enediolate Complex: Synthesis, Characterization, and O2 Reactivity

Using a new N(4)-donor chelate ligand having a mixture of hydrophobic phenyl and hydrogen-bond-donor appendages, a trinuclear nickel(II) complex of the doubly deprotonated form of 2-hydroxy-1,3-diphenylpropane-1,3-dione was isolated, characterized (X-ray crystallography, elemental analysis, UV-vis, (1)H NMR, FTIR, and magnetic moment measurement), and evaluated for O(2) reactivity. This complex, [(6-NA-6-Ph(2)TPANi)(2)(mu-PhC(O)C(O)C(O)Ph)(2)Ni](ClO(4))(2) (4), has two terminal pseudooctahedral Ni(II) centers supported by the tetradentate chelate ligand and a central square-planar Ni(II) ion ligated by oxygen atoms of two bridging enediolate ligands. In CH(3)CN, 4 exhibits a deep orange/brown color and lambda(max) = 463 nm (epsilon = 16 000 M(-1)cm(-1)). The room temperature magnetic moment of 4, determined by Evans method, is mu(eff) = 5.3(2) mu(B). This is consistent with the presence of two noninteracting high-spin Ni(II) centers, a diamagnetic central Ni(II) ion, and an overall quintet ground state. Exposure of a CH(3)CN solution of 4 to O(2) results in the rapid loss of the orange/brown color to give a green solution. The products identified from this reaction are [(kappa(3)-6-NA-6-Ph(2)TPA)Ni(O(2)Ph)(H(2)O)]ClO(4) (5), benzil [PhC(O)C(O)Ph], and CO. Identification of 5 was achieved via its independent synthesis and a comparison of its (1)H NMR and mass spectral features with those of the 6-NA-6-Ph(2)TPA-containing product generated upon reaction of 4 with O(2). The independently prepared sample of 5 was characterized by X-ray crystallography, elemental analysis, UV-vis, mass spectrometry, and FTIR. The O(2) reactivity of 4 has relevance to the active-site chemistry of Ni(II)-containing acireductone dioxygenase (Ni(II)ARD).

Synthesis, characterization and bioactivity of two novel trinuclear Cu(II)/Ni(II) complexes with pentadentate ligand N-2-methyl-acryloyl-salicylhydrazide

Two new trinuclear complexes, Cu 3L 2(py) 2 ( 1) and Ni 3L 2(py) 4 ( 2), have been synthesized and characterized, where L 3− is N-2-methyl-acryloyl-salicylhydrazidate. Central metal ion and two terminal metal ions in the two complexes are combined by two bridging deprotonated L 3− ligands, forming a bent trinuclear structure unit with an M–N–N–M–N–N–M core. The bent angles in complexes 1 and 2 are 167.6(1)° and 75.4(1)°, respectively. Three nickel ions in compound 2 exhibit alternating square-planar and octahedral geometries, while three copper ions in compound 1 follow square-planar mode. The studies in solution integrity and stability of compounds 1 and 2 show they are soluble and stable in DMF. UV–Vis titrations demonstrate compound 1 is stable in DMF even in the presence of excess metal ions. Antibacterial screening data indicate the two compounds all have stronger antimicrobial activities against the tested microorganisms than ligand. The trinuclear copper compound 1 is more active than monocopper compounds in the previous study, and the trinuclear nickel compound 2 is less active than tetranuclear nickel compound in the previous study.

A trinuclear nickel(II) complex with dissimilar bridges: Synthesis, crystal structure, spectroscopy and magnetism

A novel trinuclear nickel(II) complex with dissimilar bridges: [Ni 3(HL) 2(CH 3COO) 4(CH 3OH) 2]·2H 2O·2CH 3OH ( 1), where H 2L = N-(2-hydroxybenzyl)salicylaldimine, has been synthesized and structurally as well as magnetically characterized. Compound 1 has the discrete trinuclear structure, bridged by the phenolic oxygen, a single oxygen and a double oxygen bridge of acetate ions. The magnetic data of complex 1 were analyzed by means of H ˆ = - 2 J ( S ˆ 1 S ˆ 2 + S ˆ 2 S ˆ 3 ) + D [ S ˆ Z 2 - S ( S + 1 ) / 3 ] δ S , S = 3 , leading to J = 4.31 cm −1, g = 2.02, D = 1.22 cm −1.

Structure and magnetic properties of a trinuclear nickel(II) complex with benzenetricarboxylate bridge

Novel trinuclear Ni(II) complex [Ni 3(pmdien) 3(btc)(H 2O) 3](ClO 4) 3 · 4H 2O, 1 where pmdien = N, N, N′, N′, N″-pentamethyldiethylenetriamine, H 3btc = 1,3,5-benzenetricarboxylic (trimesic) acid, has been prepared and structurally characterized. Three nickel atoms are bridged by btc trianion and their coordination sphere is completed by three N atoms of pmdien and O atom of the water molecule. The three nickel(II) magnetic centers are equivalent and their coordination spheres are completed to deformed octahedrons. Magnetic susceptibility was measured over the temperature range 1.8–300 K and zJ′ = −0.19 cm −1, D = 3.79 cm −1, g = 2.18 parameters were calculated.

Mixed-ligand coordination polymers from 1,2-bis(1,2,4-triazol-4-yl)ethane and benzene-1,3,5-tricarboxylate: Trinuclear nickel or zinc secondary building units for three-dimensional networks with crystal-to-crystal transformation upon dehydration

The hydrothermal reaction of M(NO3)2.6H2O (M = Ni and Zn) with benzene-1,3,5-tricarboxylic acid (H3btc) and 1,2-bis(1,2,4-triazol-4-yl)ethane (btre) produced the mixed-ligand coordination polymers (MOFs) 3 infinity{[Ni3(mu3-btc)2(mu(4)-btre)2(mu-H2O)2]. approximately 22H2O} (1) and 3 infinity{[Zn3(mu4-btc)2(mu4-btre)(H2O)2].2H2O} (3). The compounds, characterized by single-crystal X-ray diffraction, X-ray powder diffraction and thermoanalysis feature trinuclear secondary building units (SBU) within the three-dimensional frameworks. The trinuclear nickel unit in 1 exhibits an intra-trimer together with some weak inter-trimer antiferromagnetic coupling with J = -13.88(8) cm(-1) from the magnetic susceptibility measurement between 1.9-300 K. The zinc coordination polymer 3 shows a strong fluorescence at 423 nm upon excitation at 323 nm (not seen in the free btre ligand). Compound 3 is thermally robust until 200 degrees C (ambient pressure) where loss of the water molecules starts. Careful control of the dehydration procedure (freeze-drying) for 1 and (heating to 280 degrees C) for allowed for a solid-state reaction with single-crystal-to-single-crystal structural transformations in obtaining the largely dehydrated products 3 infinity{[Ni3(mu2-btc)2(mu4-btre)2(mu-H2O)2(H2O)2].4H2O} (2) and 3 infinity{[Zn3(mu6-btc)2(mu4-btre)2]. approximately 0.67H2O} (4), respectively. In the transformation from 1 to 2 the unit cell volume is reduced to about 60%. The transition from 3 to 4 involves breakage and formation of new Zn-O bonds.

Synthetic, structural, electrochemical and solvent extraction studies of neutral trinuclear Co(ii), Ni(ii), Cu(ii) and Zn(ii) metallocycles and tetrahedral tetranuclear Fe(iii) species incorporating 1,4-aryl-linked bis-β-diketonato ligands

Uncharged complexes, formulated as trimeric metallocycles of type [M3(L(1))3(Py)6] (where M = cobalt(II), nickel(II) and zinc(II) and L(1) is the doubly deprotonated form of a 1,4-phenylene linked bis-beta-diketone ligand of type 1,4-bis(RC(O)CH2C(O))C6H4 (R = t-Bu)) have been synthesised, adding to related, previously reported complexes of these metals with L(1) (R = Ph) and copper(ii) with L(1) (R = Me, Et, Pr, t-Bu, Ph). New lipophilic ligand derivatives with R = hexyl, octyl or nonyl were also prepared for use in solvent extraction experiments. The X-ray structures of H2L(1) (R = t-Bu) and of its trinuclear (triangular) nickel(II) complex [Ni3(L(1))3(Py)6].3.5Py (R = t-Bu) are also presented. Electrochemical studies of H2L(1), [Co3(L(1))3(Py)6], [Ni3(L(1))3(Py)6], [Cu3(L(1))3], [Zn3(L(1))3(Py)6] and [Fe4(L(1))6] (all with R = t-Bu) show that oxidative processes for the complexes are predominantly irreversible, but several examples of quasireversible behaviour also occur and support the assignment of an anodic process, seen between +1.0 and +1.6 V, as involving metal-centred oxidations. The reduction behaviour for the respective metal complexes is not simple, being irreversible in most cases. Solvent extraction studies (water/chloroform) involving the systematic variation of the metal, bis-beta-diketone and heterocyclic base concentrations have been performed for cobalt(II) and zinc(II) using a radiotracer technique in order to probe the stoichiometries of the respective extracted species. Significant extraction synergism was observed when 4-ethylpyridine was also present with the bis-beta-diketone ligand in the chloroform phase. Competitive extraction studies demonstrated a clear uptake preference for copper(II) over cobalt(II), nickel(II), zinc(II) and cadmium(II).

Synthesis and Characterization of Two Trinuclear Nickel(II) Complexes

AbstractTwo novel trinuclear nickel(II) complexes have been synthesized and characterized by X‐ray single crystal diffraction. Compound [Ni3(ashz)3(py)2(DMF)2]·(DMF)2 (1) crystallizes in the monoclinic, space group C2/c, with a = 22.114(2), b = 10.509(9), c = 19.485(2) Å, β = 114.443(1)°, Z = 4; compound [Ni3(acshz)3(py)2(DMF)2]·(DMF)2 (2) crystallizes in the monoclinic space group P21/n with a = 20.0620(2), b = 9.7017(6), c = 25.0533(2) Å, β = 97.0610(2)°, Z = 4, where ashz and acshz are deprotonated N‐acetylsalicylhydrazide (H3ashz) and N‐acetyl‐5‐chlorosalicylhydrazide (H3acshz), respectively. The crystal structure analysis of 1 and 2 showed that three Ni2+ ions in a linear arrangement are bridged by two ligands ((ashz)3− or (acshz)3−) to form a neutral nuclear with two four‐coordinate square‐planar nickel ions linked by a six‐coordinate octahedral central nickel ion.

Vinyl polymerization of norbornene by mono‐ and trinuclear nickel complexes with indanimine ligands

AbstractA series of new indanimine ligands [ArNCC2H3(CH3)C6H2(R)OH] (Ar = Ph, R = Me (1), R = H (2), and R = Cl (3); Ar = 2,6‐i‐Pr2C6H3, R = Me (4), R = H (5), and R = Cl (6)) were synthesized and characterized. Reaction of indanimines with Ni(OAc)2·4H2O results in the formation of the trinuclear hexa(indaniminato)tri (nickel(II)) complexes Ni3[ArN = CC2H3(CH3)C6H2(R)O]6 (Ar = Ph, R = Me (7), R = H (8), and R = Cl (9)) and the mononuclear bis(indaniminato)nickel (II) complexes Ni[ArNCC2H3(CH3)C6H2(R)O]2 (Ar = 2,6‐i‐Pr2C6H3, R = Me (10), R = H (11), and R = Cl (12)). All nickel complexes were characterized by their IR, NMR spectra, and elemental analyses. In addition, X‐ray structure analyses were performed for complexes 7, 10, 11, and 12. After being activated with methylaluminoxane (MAO), these nickel(II) complexes can polymerize norbornene to produce addition‐type polynorbornene (PNB) with high molecular weight Mv (106 g mol−1), highly catalytic activities up to 2.18 × 107 gPNB mol−1 Ni h−1. Catalytic activities and the molecular weight of PNB have been investigated for various reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 489–500, 2008

Coordination behaviour of ferrocenylthiosemicarbazone in a novel hetero trinuclear nickel(II) complex: Synthesis, spectral, electrochemistry and X-ray crystallography

The coordination behaviour of ferrocenylthiosemicarbazone was investigated in a trinuclear [Ni(Fctsc) 2] complex. The structure of the complex has been studied by X-ray crystallography. The complex crystallizes in rhombohedral space group R 3 ¯ c with six molecules per unit cell has the dimensions of a = 28.8042(2) Å, b = 28.8042(2) Å and c = 19.5131(3) Å, α = 90°, β = 90°, γ = 120°. The electronic communication between the metal centers has been studied by cyclic voltammetry.

Synthesis, Characterization and Crystal Structure of a Novel Tri‐nuclear Ni(II) Cluster Bearing Tetra‐µ‐phenoxo and Di‐µ‐acetato Bridges

A novel trinuclear nickel (II) cluster {[NiL(EtOH)]2(OAc)2Ni} · 2EtOH has been synthsized and characterized by elemental analyses, TG‐DTA, IR and 1H‐NMR etc. The X‐ray crystallography of the cluster indicates that the ligand moieties of the cluster provide the N2O2 donors set to Ni2, while one oxygen atom of the μ‐acetato and one oxygen atom of the ethanol molecule coordinate to Ni2, consequently forming a slightly distorted octahedral geometry. The double μ‐acetato bridges adopt the more familiar μ O‐C‐O form which connect the Ni2‐Ni1 and Ni1‐Ni2#, respectively, so quadruple µ‐phenoxo oxygens from 2 ligand moieties and double oxygen atoms from µ‐acetato constitute another octahedral geometry. It is worthy noting that the distance from the Ni1 to Ni2 (3.089Å) is significantly longer than other coordination bond, shows a weaker interaction. In addition, the HOMO and LUMO levels of the cluster were deduced.

A novel trinuclear nickel(II) complex of an unsymmetrical tetradentate ligand involving bridging oxime and acetylacetone functions

A novel trinuclear nickel(II) complex, [Ni 3(L) 2(H 2O) 2](ClO 4) 2, where L is a bridging unsymmetrical tetradentate ligand, involving o-phenylenediamine, diacetyl monoxime and acetylacetone (H 2L = 4-[2-(3-hydroxy-1-methyl-but-2-enylideneamino)-phenylimino]-pentan-2-one oxime) has been synthesized and characterized structurally. In the complex, an octahedral Ni(II) centre is held in the middle by two square planar units with the aid of oxime and ketonic bridges.

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

A novel linear trinuclear nickel(II) complex, [Ni 3(H 2O) 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.

Bis(dimethylformamide-2κO)bis[μ-1-(2-oxidobenzoyl)-2-(phenoxyacetyl)hydrazine(3−)]-1κ3O,N,O′:2κ2N,O′′;2κ2N,O′′:3κ3O,N,O′-dipyridine-1κN,3κN-trinickel(II)

The trinuclear nickel(II) title compound, [Ni3(C15H12­N2O4)2(C5H5N)2(C3H6NO)2], possesses a crystallographically imposed centre of symmetry. The central Ni atom adopts an axially elongated octa­hedral geometry, involving two N and two O atoms from two phenoxy­acetyl­salicylhydrazidate ligands in the equatorial plane and two O atoms from two dimethyl­formamide mol­ecules in the axial positions. The inversion-related outer Ni atoms have square-planar coordination environments provided by two O atoms and one N atom of a phenoxy­acetyl­salicylhydrazidate ligand and by the N atom of a pyridine mol­ecule. The shortest metal–metal separation is 4.6038 (11) Å. The mol­ecular structure is stabilized by intra­molecular C—H⋯O hydrogen-bonding inter­actions.

A tetranuclear nickel(II) cluster: bis[μ3-2,6-bis(methylamino)pyridine(2−)-κ4N2:N1,N6:N6]bis[μ3-2,6-bis(methylamino)pyridine(1−)-κ3N1:N2:N2]dichloridotetranickel(II)

The title compound, [Ni4(C7H9N3)2(C7H10N3)2Cl2], was obtained from a reaction in which 2,6-dimethyl­amino­pyridine, in the presence of methyl­lithium used to deprotonate the organic ligand precursor, was added to NiCl2 during an attempt to synthesize a linear trinuclear nickel chain. During this reaction, two equivalents of the amine were fully deprotonated, forming dianions, and the three N atoms coordinate to Ni centers. The other two equivalents of the amine were only partially deprotonated, giving monoanions in which only two N atoms coordinate to Ni centers. In this tetra­nuclear complex, two of the four Ni atoms have square-planar coordination and are bonded to four N donors, while the other two are in a distorted tetra­hedral geometry, with three coordination sites occupied by N donors and the fourth by a Cl atom. The mol­ecule is noncentrosymmetic but the crystal structure is racemic.

Formation of Strong OH2···-O2C Hydrogen Bonds in a Trinuclear Core-Based Nickel 1,3,5-Benzenetricarboxylate Coordination Polymer

The nickel 1,3,5-benzenetricarboxylate (1,3,5-btc3-) coordination polymer, [Ni6(μ-OH2)4(1,3,5-btc)4(H2O)12]n (1), has been synthesized using a hydrothermal reaction. Trinuclear nickel cores constructed from the μ-OH2 and carboxylate bridges are linked by the 1,3,5-btc3- ligands, forming a two-dimensional network. The μ-OH2 molecules form strong hydrogen bonds with the free oxygens of the carboxylate groups in the trinuclear clusters. A structural phase transition occurs around 373 K and is categorized as a second-order phase transition.

Triaminoguanidine derivatives as supports to construct magnetic assemblies: Synthesis and characterization of trinuclear nickel(II) complexes

The synthesis of two nickel(II) complexes based on a central bridging triaminoguanidine scaffold and a capping ligand per metal ion is reported. When 2,2′-bipyridine (bipy) is utilized as co-ligand the complex [Ni 3L Br(bipy) 3(H 2O) 3]NO 3 · 9H 2O · 1.5DMF ( 1) is obtained which crystallizes in the hexagonal space group P 6 3 / m . Complex 1 shows an interesting supramolecular structure pattern with alternating hydrophilic and hydrophobic layers characterized by extensive hydrogen-bonding and π–π-stacking, respectively. With 2,4,6-(2-pyridyl)-1,3,5-triazine (tptz) as capping ligand, complex [Ni 3L Br(tptz) 3]ClO 4 · 7H 2O · 1.5DMF ( 2) is obtained. The magnetic susceptibility data can be fitted using an equilateral triangle model ( H ^ = - J ( S ^ 1 S ^ 2 + S ^ 2 S ^ 3 + S ^ 1 S ^ 3 ) ) with an isotropic coupling constant of J = - 31.0 ± 0.6 for 1 and J = - 30.9 ± 0.3 cm - 1 for 2.

Influence of pH values on the self-assembly in three trinuclear nickel complexes with bridging ligand N-salicylyl 4-phenyl-thiosemicarbazide

Three trinuclear nickel complexes containing N-salicylyl 4-phenyl-thiosemicarbazide(abbreviated as spt 3−) have been synthesized. They are complex [Ni 3(spt) 2(dpt) 2]·2C 3H 7NO ( 1) with 2,5-diphenylamiyl 1,3,4 thiodiazone ligand(dpt) and the other two complexes without dpt ligand ([Ni 3(spt) 2(H 2O) 4]·2C 3H 7NO ( 2) and [Ni 3(spt) 2(C 5H 5N) 2(H 2O) 2]·2C 3H 7NO ( 3)). Central Ni atom and two terminal Ni atoms in the three complexes are combined by two bridging deprotonated spt 3− ligands, forming a strictly linear trinuclear nickel structure unit with a Ni N N Ni N N Ni core. There is an extended 1D structure in 2 and 3 formed by intermolecular hydrogen bonds O H…O. The influence of pH of the reaction medium upon the composition of the final products is discussed.

Novel trinuclear copper(II) and nickel(II) metallochelates with nitromalonodialdehyde bis(acylhydrazones)

Novel trinuclear copper(II) and nickel(II) metallochelates with nitromalonodialdehyde bis(acylhydrazone) are synthesized. The compositions and structures of the ligand and complexes are determined from the data of elemental and thermographic analyses, IR and NMR spectroscopies, and magnetochemistry. Details of magnetochemical behavior of the metallochelates synthesized are discussed.

Di-μ-acetato-bis[μ-2-hydroxy-N,N′-bis(2-oxidobenzyl)propane-1,3-diamine]bis(N,N′-dimethylformamide)trinickel(II)N,N′-dimethylformamide disolvate

The title compound, [Ni3(C17H20N2O2)2(C2H3O2)2(C3H7NO)2]·2C3H7NO, is a centrosymmetric trinuclear nickel(II) complex. The central and terminal nickel(II) atoms have distorted octa­hedral coordination, the central NiII atom by six O atoms, and the terminal NiII atoms by four O atoms and two N atoms each. The average Ni—O and Ni—N distances for the terminal Ni ions are 2.062 (17) and 2.082 (2) Å, respectively. The Ni⋯Ni distance is 3.035 (2) Å.

Syntheses, Structures and Antibacterial Activities of Two Nickel(II) Complexes with N‐Hexanoylsalicylhydrazide Ligand

AbstractThe two trinuclear nickel(II) complexes, Ni3(C13H15N2O3)2(C5H5N)4 (1) and Ni3(C13H15N2O3)2(C5H5N)2‐ (C3H7NO)2 (2), were prepared by the reaction of Ni(OAc)2·4H2O with N‐hexanoylsalicylhydrazide. The crystal structures of complexes were determined by X‐ray diffraction analysis. Complex 1 takes triclinic symmetry with space group P‐1 and cell dimensions of a=0.92377(2) nm, b=1.08786(6) nm, c=1.29391(3) nm, α=76.395(4) °, β=78.418(3)°, γ=67.378(4)°, V=1.15772(7) nm3, Z=1, µ=12.63 cm−1. Complex 2 belongs to triclinic system and P2(1) space group and the crystallographic data: a=1.4889(2) nm, b=1.0389(1) nm, c=1.4994(2) nm, β=96.174(4)°, V=2.3058(5) nm3, Z=2, µ=12.70 cm−1. The structures of the two molecules are similar. The three nickel atoms in each molecule of the two title complexes arrange in a strictly linear structure. The central nickel atom of the molecule adopts octahedral configuration, while the two nickel atoms on the two sides adopt square‐planar configuration in each molecule. But the central nickel atoms of the two complexes have different axial ligands, which cause a slight difference in the bond distances of the octahedron. The antibacterial activity of compound 1 against seven common bacteria was investigated.