A dioxotetraamine fluorenyl ligand and its nickel(II) complex — crystal structure and fluorescent sensing properties in aqueous solution

A new ligand consisting of fluorenyl and dioxotetraaza units, namely, 2,10-diamino-6-(9H-fluoren-9-yl)-4,8-diazaundecane-5,7-dione (L), and its nickel(II) complex were synthesized. The crystal structure of [Ni(H₋₂L)] showed that Ni(II) is in a square planar coordination environment. Studies of solution chemistry of the ligand and its nickel(II) complex indicate that the ligand can form a stable complex with Ni²⁺ ions and fluorescence quenching of the ligand is accompanied by the coordination of the metal ion to the dioxotetraaza unit and electron transfer from the Ni(II) center to fluorenyl in aqueous solution.     

Mixed-ligand ternary complexes of potentially pentadentate but functionally tridentate Schiff base chelates

The potentially pentadentate chelate 2,6-diacetylpyridine-bis(N-methyl-S-methyldithiocarbazate) (Nmedapsme) has been synthesized and structurally characterized by X-ray diffraction. Its reactions with nickel(II) salts did not lead to pentadentate coordinated ligand complexes but ternary complexes of general formula, [Ni(Nmedapsme)(nmesme)L]X·H₂O (L = Br⁻, I⁻; X = I⁻, BF₄⁻) where Nmedapsme binds as a tridentate and nmesme = N-methyl-S-methyldithiocarbazate. The related ternary nickel(II) complexes of formula, Ni(Nmedapsme)(nmetsc)Br₂ has also been prepared and characterized. X-ray crystal structures of [Ni(Nmedapsme)(nmesme)I]I·H₂O and [Ni(Nmedapsme)(nmesme)Br]BF₄·H₂O revealed that, in these complexes, the Nmedapsme ligand acts as a tridentate NNN donor while the distal S-donors are not coordinated. The bidentate (NS) ligand, nmesme coordinates to the nickel(II) ion via the amino nitrogen and the thione sulfur atoms, the sixth coordination site is occupied by an anion. In both complexes, the nickel(II) ion adopts a distorted octahedral configuration. The complex [Cu(nmesme)₂(ONO₂)]NO₃ was obtained from an unsuccessful attempt to complex copper(II) with Nmedapsme. Hydrolysis of the parent Schiff base Nmedapsme occurred during complexation. An X-ray crystallographic structure analysis shows that the complex, [Cu(nmesme)₂(ONO₂)]NO₃ has an approximately square-pyramidal geometry with the two nmesme ligands coordinated to the copper(II) ion as NS bidentate chelating agents via the amino nitrogen and thione sulfur atoms and the fifth coordination position of copper(II) is occupied by a monodentate nitrate ligand.     

The Coordination Structure of the Extracted Nickel(II) Complex with a Synergistic Mixture Containing Lix63 and Versatic10

In the present work, the nickel(II ) synergist complex with isobutyric acid (HL^I ) and 5‐hydroxy‐4‐octanone oxime (HB^I ), which were the corresponding short‐chain analogs of the active synergistic mixture of Versatic10 (HL ) and Lix63 (5,8‐diethyl‐7‐hydroxy‐6‐dodecanoneoxime, HB ), was prepared and studied by single‐crystal X‐ray diffraction (XRD ). The crystal structure of the nickel(II ) synergist complex showed that the composition of the complex was Ni(L^I )₂(HB^I )₂ with a cis ‐form octahedron geometry structure. Both intra‐ and intermolecular hydrogen bonding were observed in the crystal lattice. Compared with the free ligands, similar band shifts of Fourier transform infrared (FT‐IR ) spectra assigned to the stretching vibration of carbon–oxygen single bond (C O), the stretching vibration of carbon–nitrogen double bond (CN), and the disappearance of the scissoring vibration of α‐hydroxy (OH ) were correspondingly found in both the nickel(II ) synergist complex and the extracted nickel(II ) complex in the nonpolar organic phase. Combined with the results from ESI‐MS , XRD , and slope analysis, it was concluded that the major species of the extracted nickel(II ) complex in the nonpolar organic phase might possess a similar coordination structure [Ni(HB )₂(L)₂] as the nickel(II ) synergist complex, along with the neutral complex [Ni(HB )(B)₂].     

Synthesis,Characterization and Thermal Decomposition of p-iodo-phenylalanine Complexes of Cobalt or Nickel

New complexes of the non-natural amino acid (p-iodo-phenylalanine) with divalent cobalt and nickel ions have been synthesized. The composition of the complexes is [M(IC₆H₄CH₂CHNH₂COO)₂]×2.5H₂O (M=Co, Ni) and the crystal structure belongs to orthorhombic system. Infrared spectra indicate the nature of bonding in the complex. The first stage in the thermal decomposition process of the complex shows the presence of crystal water. The thermal decomposition process of cobalt complex differs from that of nickel. The intermediate and final residues in the thermal decomposition process have been analyzed to check the pyrolysis reactions. Thermal analysis indicates that the iodine atom of the ligand may coordinate to the metal ion in the lattice. This revised version was published online in August 2006 with corrections to the Cover Date.     

双核Ni(II)配合物[C17H20N4Ni(H2O)Cl]2Cl2•(CH3OH)的晶体结构及其模板合成新配体

采用“一锅煮”方法, 在金属Ni(II)离子作用下, 以2-乙酰吡啶和1,2-丙二胺物质的量比为2∶1进行反应, 得到了一种新的闭环单Schiff碱N₄四齿配体的配合物[C₁₇H₂₀N₄Ni(H₂O)Cl]₂Cl₂•(CH₃OH). 配合物的晶体结构测定表明, 其配位单元为N桥连的双核配合物, 配位单元间再通过氢键连接成一维链状结构.     

Hydrogen bonded networks based on Ni(II)-tetraazamacrocycle (tet-b) complexes: synthesis,isolation and structural characterization of α -[Ni(tet-b)(Cl)](ClO4) and α -[Ni(tet-b)(en)](ClO4)2

Five- and six-coordinate, α-[Ni(tet-b)(Cl)](ClO₄) (1) and α-[Ni(tet-b)(en)](ClO₄)₂ (2) (tet-b?= C-racemic-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) complexes have been synthesized and isolated from the reactions of α-[Ni(tet-b)](ClO₄)₂, which has trans-V (1R,4R,8R,11R,7S,14S or 1S,4S,8S,11S,7R,14R) conformation, with t-Bu₄NCl and ethylenediamine (en), respectively. The complexes have been characterized by X-ray crystallography. The crystal structure of 1 shows a distorted trigonal bipyramidal (TBP) coordination geometry composed of four nitrogen atoms from tet-b and a chloro group with an N₄Cl chromophore about the nickel(II) ion. The complex cations of 1 are assembled by the perchlorate ions via N–H?···?O hydrogen bonding to form 1-D zigzag chains along the [001] direction. The chains are linked through intermolecular hydrogen bonding where the coordinated chloro group of the complex cation forms two-center double hydrogen bonds with the adjacent N–H groups of the macrocyclic ligand along the [100] direction, resulting in a two-dimensional α-network. The crystal structure of 2 shows a distorted octahedral coordination environment consisting of four nitrogen atoms from tet-b and two from en with an N₆ chromophore about nickel(II) ion. The crystal packing analysis shows that the complex cations, α-[Ni(tet-b)(en)]²⁺ are interconnected by perchlorate ions through conventional two-center (N)H?···?O, and bifurcated (N)H?···?O?···?H(N) hydrogen bonding.     

Nickel complexes of N,N,N',N'′-tetrakis-(2- benzimidazolylmethyl)-1,2-diaminoethane (L) and the X-ray crystal structure of {[NiL]2+ [NiCl2(H2O)3(C2H5)OH)]}2Cl−(C2H5OH)

The preparation and properties of Ni(II) complexes of the title ligand (L) are described and the X-ray crystal structure of Ni₂LCl₄(H₂O)₃(C₂H₅OH)₂ is reported. The crystal structure shows that the two nickel ions are not bridged but exist as two distinct distorted octahedral species. Six coordination about one nickel ion is produced exclusively by L to give the cationic species [NiL]²⁺. The second nickel ion achieves six coordination through an interesting combination of ligands to produce the novel complex [NiCl₂(H₂O)3 (C₂H₅OH)]. Since the two remaining chloride ions are hydrogen bonded to two of the water molecules and the ethanol molecule of [NiCl₂(H₂O)₃(C₂H₅OH)] the entire complex can be considered to be formed by the cocrystallization of the large cation [NiL]²⁺ by the “large anion” {[NiCl₂(H₂O)₃(C₂H₅OH)]Cl₂}²⁻.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 1. The4N-methyl derivative

Summary A series of metal ion complexes of the thiosemicarbazone,N-methyl-2[1-(2-pyridinyl)ethylidene]-hydrazinecarbothioamide (HL4M) has been prepared and spectrally characterized. HL4M coordinates either as a neutral bidentate ligand (i.e., pyridyl N and imine N) or as deprotonated tridentate ligand (i.e., pyridyl N, imine N and thiol sulphur). The cobalt(II) salts yield hexacoordinated cobalt(III) cations, and an isoelectronic species, [Ni(L4M)₂], has been formed from Ni(C₂H₃O₂)₂. The remaining nickel(II) complexes involve the neutral ligand, as do two of the three copper(II) complexes. HL4M possesses a weaker ligand field and has less covalency in its bonding than related thiosemicarbazones that possess anN-dialkyl-function.     

Supramolecular and metallosupramolecular coordination compounds of nickel(II) with the half units of vicinal oxime–imine ligands; mixed ligand complexes of the metal ion

The [1+1] condensation of isonitrosoacetylacetone (Hisoacac) with o-phenylenediamine produces the diazepine (HLBD) (1), which reacts with Ni(OAc)₂· 4H₂O (1:1 molar ratio) to produce the mixed ligand complex (LBDN)Ni(OAc) (2); where LBDN is the anion of the half unit obtained by hydrolysis of one HLBD imine linkage. The reaction of (2) (1 mol) with mono-, bi- and trichloroethanoic acid (1mol) or picric acid (1mol) led to the exchange of the acetate in (2) with the anion of the added acid [(3)–(6), respectively]. The supramolecular structure of (2)–(6) is achieved through the dimerization of these complexes via intermolecular hydrogen bonding of the LBDN –NH₂ group of one molecule and the monodentate acetate group of another molecule. The template reaction of o-phen with Hisoacac in the presence of Ni(OAc)₂·4H₂O (1:2:2 and 1:2:1 molar ratios, respectively) led to the formation of (LBDN)Ni(OAc)₂Ni(isoacac) (7) and (isophen)Ni (8), respectively; H₂isophen is a symmetrical Schiff base ligand formed by the (2:1) in situ condensation of Hisoacac with o-phen. The (1:1) condensation of Hisoacac with p-phen produced the half unit Hisopphen (9), whose 1:1 molar ratio reaction with Ni(OAc)₂·4H₂O led to the formation of (isopphen)Ni(OAc)·2H₂O (10). The amino group of the isopphen ligand is available for further coordination with the nickel(II) ion to produce the metallosupramolecular complexes {[two molecules of complex (10)] [Ni(OAc)₂]} and {[complex (10)] [Ni(OAc)₂·H₂O]} from the 2:1 and 1:1 molar ratio reactions, respectively, of (10) with Ni(OAc)₂·4H2O. The 1:1 molar ratio reaction of (10) with Hisoacac led to replacement of OAc by isoacac. The suggested structures of the ligands and their coordination compounds are based on analytical, chemical, spectral data and magnetic moments.     

Supramolecular Hydrogen‐Bonded Frameworks from a New Bisphosphonic Acid and Transition Metal Ions

The reaction of 2‐morpholinoethylimino‐bis(methylenephosphonic acid) (H₄L) with cobalt(II), nickel(II) acetate, and cadmium(II) chloride in ethanol/water mixed solvents afforded three new crystal‐engineered supramolecular metal phosphonates, Co(H₃L)₂ · 2H₂O ( 1 ), Ni(H₃L)₂ · 2H₂O ( 2 ), and [Cd₂Cl₄(H₂O)₆]_0.5[H₄L] ( 3 ) by using a layering technique. The cobalt(II) ions in complex 1 are hexacoordinated by four phosphonate oxygen atoms and two imino nitrogen atoms. The mononuclear units of complex 1 are connected through hydrogen bonds to form a three dimensional supramolecular network. The structure of compound 2 is analogous to that of 1 except that the cobalt(II) ion in compound 1 is replaced by nickel(II) in compound 2 . In the molecular structure of compound 3 , cadmium is coordinated to three chloride ions and three aqua oxygen atoms to form a novel neutral dinuclear complex. Several hydrogen bonds connect the dinuclear complex and the neutral form of the ligand to build a supramolecular three dimensional structure.     

Synthesis,Spectral Studies and Bio‐activity of Some Ligand Bridged Polymeric Transition Metal Complexes of Acetone p‐Amino Acetophenone Isonicotinoyl Hydrazone

Ligand bridged polymeric complexes of the type [M(apainh)(H₂O)X] where, M=Mn(II), Co(II), Ni(II), Cu(II), and Zn(II); X=Cl₂ or SO₄; apainh=acetone p‐amino acetophenone isonicotinoyl hydrazone have been synthesized and characterized. The complexes are stable solids, insoluble in common organic solvents and are non‐electrolytes. Magnetic moments and electronic spectral studies suggest a spin‐free octahedral geometry for all Mn(II), Co(II), Ni(II), and Cu(II) complexes. IR spectra show tridentate nature of the ligand bonding through two >C?N and a >C?O groups. X‐ray powder diffraction parameters for some of the complexes correspond to orthorhombic and tetragonal crystal lattices. Thermal studies (TGA and DTA) of [Mn(apainh)(H₂O)SO₄] complex show multi‐step decomposition pattern of both an endothermic and exothermic nature. ESR data of Cu(II) chloride complex in solid state show an axial spectra, whereas, Cu(II) sulfate complex is isotropic in nature. The complexes show a significant antifungal activity against a number of pathogenic fungal species and antibacterial activity against Pseudomonas sp. and Clostridium sp. The metal complexes are more active than the ligand.     

Syntheses,Crystal Structures,and Magnetic Properties of Two Mononuclear Nickel‐Nitronyl Nitroxide Radical Compounds

Two nickel(II) complexes were synthesized and structurally as well as magnetically characterized by using two positional isomeric nitronyl nitroxide radical ligands and H₃cda as co‐ligand: [Ni(NIToPy)(cda)]H₂O · CH₃OH ( 1 ) and [Ni(IM4Py)₂(cda)H₂O] ( 2 ) [NIToPy = 2‐(3′‐pyridinyl)‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazolyl‐1‐oxyl‐3‐oxide; IM4Py = 2‐(4′‐pyridinyl)‐4,4,5,5‐tetramethylimidazoline‐l‐oxyl; H₃cda = 4‐hydroxypyridine‐2,6‐dicarboxylic acid]. Single‐crystal structures analyses show that both complexes have similar mononuclear structures, in which the central Ni^II ions are hexacoordinated with a distorted octahedral arrangement. The magnetic properties of 1 and 2 were studied, and antiferromagnetic interactions between Ni^II ion and radicals are observed.     

A nickel(II) coordination polymer derived from a tridentate Schiff base ligand with N,O-donor groups: synthesis,crystal structure,spectroscopy, electrochemical behavior and electrocatalytic activity for H<Subscript>2</Subscript>O<Subscript>2</Subscript> electroreduction in alkaline medium

A Ni(II) coordination polymer [C₄₂H₄₂K₂N₄Ni₄O₂₇] has been synthesized under open-air mild reaction conditions and characterized by physicochemical and spectroscopic methods. The X-ray crystal structure of the complex has been obtained. The crystallographic data revealed that each metal center is in a distorted octahedral geometry where the ligand coordinates to the metal centers by a nitrogen from the imine group, an oxygen from the carboxylic acid and a phenoxide group as an endogenous bridge to the metal centers. The coordination sphere is completed by an acetate, coordinated as an exogenous bridging ligand to both nickel centers, plus one terminal water ligand on each nickel. The polymeric structure is an infinite chain involving the binuclear nickel structure and K⁺ ions. Carbon paste electrodes modified with the Ni(II) coordination polymer were prepared, and the electrochemical behavior and electrocatalytic activity toward H₂O₂ reduction were investigated. The electrochemical results suggest that this Ni(II) coordination polymer has good catalytic activity with respect to H₂O₂ reduction.     

A novel dimeric zinc(II) complex with a tripodal peptide ligand: a structure stabilized by ligand sharing

The crystal structure of a novel dimeric zinc(II) complex, [ZnL(H₂O)]₂(ClO₄)₂·4H₂O (L?=?N-(bis(2-pyridyl)methyl)-2-pyridinecarboxamide), has been determined by X-ray diffraction. In this complex each planar N_py–N_amido–N_py moiety of the ligand coordinates to one zinc ion and the pendant pyridine of one [ZnL] unit completes the coordination sphere of a [ZnL] neighbor. Units of the complex are connected in a two-dimensional network by intermolecular hydrogen bonds. The thermodynamic properties of the ligand with bivalent metal ions Co(II), Ni(II), Cu(II) and Zn(II) were studied by potentiometric titration and the order of the stability constants is in agreement with the Irving–Williams series. The dimeric complex is stabilized through ligand sharing, as confirmed by the crystal structure and thermodynamic properties.     

The Unusual Thermodynamic Stability Order of the First-series Transition Metal Complexes with N,N,N′-tri(2-pyridylmethyl)glycinamide and the Crystal Structure of the Nickel(II) Complex

A new pentadentate tripodal peptide ligand N,N,N′-tri(2-pyridylmethyl)glycinamide (L) has been synthesized. The crystal structure of its nickel(II) complex, [NiL(H₂O)] · 1.17ClO₄ · 0.17H₃O · 0.03H₂O (1), has been determined by X-ray diffraction. In the complex, the deprotonated ligand L acts in a pentadentate fashion and coordinates to the nickel(II) ion through five nitrogen atoms, while the sixth position is occupied by a water molecule. The units of the complex are connected as a 3D honeycomb network by intermolecular hydrogen bonds. The thermodynamic properties of the ligand L with the first-series transition metal ions Co(II), Ni(II), Cu(II) and Zn(II) have been investigated by potentiometric titration and the results show that the order of their stability constants does not conform to the Irving–Williams serial. The reason why the stability constants of the Cu(II) complex are unconventionally small is proposed.     

Synthesis of 2‐(N‐arylimino)pyrrolide nickel complexes and polymerization of methyl methacrylate

The synthesis, characterization and methyl methacrylate polymerization behaviors of 2‐(N‐arylimino)pyrrolide nickel complexes are described. The nickel complex [NN]₂Ni ( 1 , [NN] = [2‐C(H)NAr‐5‐tBu‐C₄H₂N]^?, Ar = 2,6‐iPr₂C₆H₃) was prepared in good yield by the reaction of [NN]Li with trans‐[Ni(Cl)(Ph)(PPh₃)₂] in THF. Reaction of [NN]Li with NiBr₂(DME) yielded the nickel bromide [NN]Ni(Br)[NNH] ( 2 ). Complexes 1 and 2 were characterized by ¹H NMR and IR spectroscopy and elemental analysis, and by X‐ray single crystal analysis. Both complexes, upon activation with methylaluminoxane, are highly active for the polymerization of methyl methacrylate to give high molecular weight polymethylmethacrylate with narrow molecular distributions. Copyright © 2009 John Wiley & Sons, Ltd.     

Coordination Mode of the Nickel(II) Cation with N‐Diisopropoxyphosphinyl‐p‐bromothiobenzamide

Reaction of the potassium salt of N‐diisopropoxyphosphinyl‐p‐bromothiobenzamide p‐BrC₆H₄C(S)NHP(O)(OiPr)₂ ( HL ) with Ni(NO₃)₂ in aqueous EtOH leads to complex of formula [Ni(HL‐O)₂(L‐O,S)₂] ( 1 ). The structure of 1 was investigated by single crystal X‐ray diffraction analysis, IR, ¹H and ³¹P{¹H} NMR spectroscopy, MALDI and microanalysis. The nickel(II) ion in 1 has a tetragonal‐bipyramidal environment, (O^ax)₂(O^eq)₂(S^eq)₂, with two neutral ligand molecules coordinated in axial positions through the oxygen atoms of the P=O groups. The equatorial plane of bipyramide is formed by two anionic ligands involving 1,5‐O,S‐coordination mode. The chelating ligands are bound in trans configuration.     

Synthesis,crystal structure and magnetic properties of a nickel(II) complex containing a 2-pyridyl-substituted nitronyl nitroxide

A new complex of formula [Ni(NIT2Py)₂Cl(H₂O)]Cl·2CH₃OH, where NIT2Py is 2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, was synthesized and characterized structurally and magnetically. The structure consists of a [Ni(NIT2Py)₂Cl(H₂O)]⁺ ion, a chloride anion and two methanol molecules. The nickel(II) ion lies in a distorted octahedral environment; two nitrogen atoms and two oxygen atoms from NIT2Py ligands from the basal plane; one oxygen atom from a water molecule and one chloride anion occupy axial positions. Variable temperature magnetic susceptibility data show that there is strong antiferromagnetic coupling between the nickel(II) ion and nitronyl nitroxide radicals. The results suggest that the sign of the magnetic interaction depends on structural and ligand effects.     

Synthesis,Characterization, X‐ray Structures,and Solution Studies of Nickel(II) Complexes of an Aza‐Crown Macrocycle with a Hydroxyl Pendant‐Armed

The 18‐membered mixed‐donor macrocycle 6,7,8,9,10,11,12,13,20,21‐decahydro‐5H, 19H‐dibenzo[b,m][1,15,5,8,11]dioxatriazacyclooctadecin‐20‐ol ( L ), which contains N₃O₃ donor set, was synthesized. Also two nickel(II) complexes of L have been synthesized and characterized by X‐ray crystallography, FT‐IR, UV‐Vis absorption spectroscopy and elemental analysis. The structure of complexes shows an unexpected anion dependence. Reaction of Ni(ClO₄)₂·6H₂O with L afforded [Ni L ](ClO₄)₂·CH₂Cl₂ complex in which L uses all donor atoms and acts as a hexadentate ligand so forming a mononuclear nickel(II) complex in distorted octahedral geometry. Contrasting with this, when NiCl₂·6H₂0 is used, the product complex [{Ni L Cl}₂(μ‐Cl)₂] is dimeric and consists of two Ni L Cl units bridged by two chloride ions. The coordination geometry of each nickel atom is a distorted octahedral. In this complex L is exo‐coordinated via only three nitrogen atoms to a nickel ion, which is bound to two cis bridging chloride and one non‐bridging chloride too. Also complexing properties of L towards Ni(ClO₄)₂·6H₂O and NiCl₂·6H₂0 have been determined by UV‐Vis titration in methanol. The computer treatment of the data confirmed the 1:1 metal to ligand stoichiometry for two complexes in solution and gave reliable values for corresponding stability constants (logK = 3.00 ± 0.02 with Ni(ClO₄)₂·6H₂O and logK = 3.29 ± 0.06 with NiCl₂·6H₂0).     

Pentanuclear Nickel(II) Complex with two Vertex-Shared Triaminoguanidine Fragments and Symmetric Capping Ligand

The pentanuclear nickel(II) complex [Ni₅(saltag^Br)₂(tptz)₄] ( Ni5 ) with the tritopic triaminoguanidine-derived Schiff-base ligand H₅saltag^Br (1,2,3-tris[(5-bromosalicylidene)amino]guanidine) and tptz (2,4,6-tris(2-pyridyl)-1,3,5-triazine) as capping ligands is reported. Ni5 crystallizes in the triclinic space group P1 with the central nickel(II) ion linking two triangular arrangements of nickel(II) ions supported by two tritopic triaminoguanidine ligands. The octahedral coordination of the four peripheral nickel(II) ions is complemented by capping tridentate tptz ligands. By variation of the synthesis also the corresponding trinuclear nickel(II) complex [Ni₃(saltag^Br)(tptz)₃]NO₃ ( Ni3 ) is accessible. Magnetic measurements for Ni3 and Ni5 reveal a singlet ground state with antiferromagnetic coupling between the nickel(II) ions, which in the case of Ni5 can only be simulated assuming a two-J exchange coupled spin topology. For both complexes significant zero-field splitting for the nickel(II) ions is evident from the measured magnetic data, which can be verified by theoretical studies revealing a magnetic anisotropy with strong rhombic distortion due to the presence of the tptz co-ligands in both compounds.