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NiII
Terms modified by NiII Selected AbstractsChemInform Abstract: Predictive Concept for Lone-Pair Distortions , DFT and Vibronic Model Studies of AXn -(n-3) Molcules and Complexes (A: NIII to BiIII; X: F - to I - ; n = 3,6).CHEMINFORM, Issue 32 2002Michael Atanasov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Influence of Metal Nanoparticles on the Electrocatalytic Oxidation of Glucose by Poly(NiIIteta) Modified ElectrodesELECTROANALYSIS, Issue 5 2010Pratap Azad Abstract Conductive polymeric [NiII(teta)]2+ (teta=C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane) films (poly(Ni)) have been deposited on the surface of glassy carbon (GC), Nafion (Nf) modified GC (GC/Nf) and Nf stabilized Ag and Au nanoparticles (NPs) modified GC (GC/Ag-Nf and GC/Au-Nf) electrodes. The cyclic voltammogram of the resulting electrodes, show a well defined redox peak due to oxidation and reduction of poly(Ni) system in 0.1,M NaOH. They show electrocatalytic activity towards the oxidation of glucose. AFM studies reveal the formation of poly(Ni) film on the modified electrodes. Presence of metal NPs increases electron transfer rate and electrocatalytic oxidation current by improving the communication within the Nf and poly(Ni) films. In the presence of metal NPs, 4 fold increase in current for glucose oxidation was observed. [source] Flow Injection Analysis of Sulfide Using a Cinder/Tetracyano Nikelate Modified Screen-Printed ElectrodeELECTROANALYSIS, Issue 9 2005Jyh-Myng Zen Abstract Flow injection analysis (FIA) of sulfide is presented using a screen-printed carbon electrode modified with a cinder/tetracyano nickelate hybrid (designated as cinder/NiTcSPE). Hybridization of NiTc was achieved in iron-enriched industrial waste cinder material through the bimetallic formation of FeIII[NiII(CN)4]. The electrocatalytic oxidation of sulfide is mediated by the higher oxidation state of Ni in this hybrid-bimetallic complex. The system shows a detection limit (S/N=3) of 0.06,,M and a linear working range up to 1,mM in pH,10, 0.1,M KCl solution. Taking into account the relatively low volatility of the analyte in alkaline conditions, the system is ideally suited for the accurate detection of sulfide. The response of the electrode to sulfide is highly reproducible, thereby offering the potential development of a disposable amperometric sensor for sulfide. Selective detection of sulfide in cigarette smoke is presented in this study as an example of a real sample application. [source] Oxido Pincer Ligands , Exploring the Coordination Chemistry of Bis(hydroxymethyl)pyridine Ligands for the Late Transition MetalsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2009Axel Klein Abstract Coordination of the 2,6-bis(hydroxymethyl)pyridine-based oxido pincer ligands RR,pydimH2 [R = R, = H (pydimH2); R = R, = Me (pydipH2); R = 2-tolyl, R, = Me (pydotH2)] towards late transition metals CoII, NiII, CuII, ZnII, PdII and PtII allows the formation of molecular species (complexes), which exhibit three main structural motifs in the solid state. The two main species are pentacoordinate [(RR,pydimH2)MCl2] and hexacoordinate [(RR,pydimH2)2M]X2, both of which are stable in solution and can be interconverted by changing the solvent polarity. The disproportionation equilibrium [(RR,pydimH2)MCl2] [rlhar2] [(RR,pydimH2)2M]2+ + [MCl4]2, was studied by optical spectroscopy. The chiral ligand pydotH2 allows the formation of chiral complexes. In the square-planar complexes [(pydimH2)2MCl2] (M = PdII or PtII) the oxido donor functions of the ligands do not take part in the coordination.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Redox Modification of EMACs Through the Tuning of Ligands: Heptametal(II) Complexes of Pyrazine-Modulated Oligo-,-pyridylamido LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2009Rayyat Huseyn Ismayilov Abstract Using pyrazine-modulated oligo-,-pyridylamido ligands N2 -(pyrazin-2-yl)- N6 -[6-(pyrazin-2-ylamino)pyridin-2-yl]pyridine-2,6-diamine (H3pzpz) and N2 -(pyrazin-2-yl)- N6 -[6-(pyridin-2-ylamino)pyridin-2-yl]pyridine-2,6-diamine (H3tpz), linear heptametal(II) extended metal atom chains (EMACs) [M7(,7 -L)4X2] [L = pzpz3,, M = NiII, X = Cl, (1), NCS, (2); M = CrII, X = Cl, (3), NCS, (4); L = tpz3,, M = CrII, X = Cl, (5), NCS, (6)] were synthesized and structurally characterized. Electrochemical studies showed that heptanickel(II) complexes can undergo one reversible oxidation at +0.46 V for 1 and +0.52 V for 2. Chromium(II) species 3 exhibited two reversible, one-electron oxidation peaks at +0.61 and +0.88 V, and 5 exhibited three reversible, one-electron oxidation peaks at +0.40, +0.68 and +1.07 V. The redox peaks shifted positively when axial ligands changed from chloride to thiocyanate anions, at +0.67 and +0.92 V for 4 and +0.44, +0.73 and +1.11 V for 6. The introduction of electron-withdrawing pyrazine rings to the spacer ligand retarded oxidation of the heptametal EMACs and stabilized the complexes. In nickel(II) species 1 and 2, both terminal nickel atoms exist in spin state S = 1 whereas all the inner nickel atoms exist in spin state S = 0. Temperature-dependent magnetic research revealed an antiferromagnetic interaction between the two terminal atoms through a superexchange pathway along metal cores with a parameter of about,4 cm,1. Chromium(II) species 3,6 showed a localized structure consisting of three quadruple Cr,Cr bonds and a single terminal CrII atom. Magnetic study revealed a quintet ground state resulting from the isolated, high-spin CrII atom.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Anion-Directed Template Synthesis and Hydrolysis of Mono-Condensed Schiff Base of 1,3-Pentanediamine and o -Hydroxyacetophenone in NiII and CuII ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2008Pampa Mukherjee Abstract Bis(o -hydroxyacetophenone)nickel(II) dihydrate, on reaction with 1,3-pentanediamine, yields a bis-chelate complex [NiL2]·2H2O (1) of mono-condensed tridentate Schiff baseligand HL {2-[1-(3-aminopentylimino)ethyl]phenol}. The Schiff base has been freed from the complex by precipitating the NiII as a dimethylglyoximato complex. HL reacts smoothly with Ni(SCN)2·4H2O furnishing the complex [NiL(NCS)] (2) and with CuCl2·2H2O in the presence of NaN3 or NH4SCN producing [CuL(N3)]2 (3) or [CuL(NCS)] (4). On the other hand, upon reaction with Cu(ClO4)2·6H2O and Cu(NO3)2·3H2O, the Schiff base undergoes hydrolysis to yield ternary complexes [Cu(hap)(pn)(H2O)]ClO4 (5) and [Cu(hap)(pn)(H2O)]NO3 (6), respectively (Hhap = o -hydroxyacetophenone and pn = 1,3-pentanediamine). The ligand HL undergoes hydrolysis also on reaction with Ni(ClO4)2·6H2O or Ni(NO3)2·6H2O to yield [Ni(hap)2] (7). The structures of the complexes 2, 3, 5, 6, and 7 have been confirmed by single-crystal X-ray analysis. In complex 2, NiII possesses square-planar geometry, being coordinated by the tridentate mono-negative Schiff base, L and the isothiocyanate group. The coordination environment around CuII in complex 3 is very similar to that in complex 2 but here two units are joined together by end-on, axial-equatorial azide bridges to result in a dimer in which the geometry around CuII is square pyramidal. In both 5 and 6, the CuII atoms display the square-pyramidal environment; the equatorial sites being coordinated by the two amine groups of 1,3-pentanediamine and two oxygen atoms of o -hydroxyacetophenone. The axial site is coordinated by a water molecule. Complex 7 is a square-planar complex with the Ni atom bonded to four oxygen atoms from two hap moieties. The mononuclear units of 2 and dinuclear units of 3 are linked by strong hydrogen bonds to form a one-dimensional network. The mononuclear units of 5 and 6 are joined together to form a dimer by very strong hydrogen bonds through the coordinated water molecule. These dimers are further involved in hydrogen bonding with the respective counteranions to form 2-D net-like open frameworks. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Receptor versus Counterion: Capability of N,N, -Bis(2-aminobenzyl)-diazacrowns for Giving Endo- and/or Exocyclic Coordination of ZnIIEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2007Lea Vaiana Abstract The structure of ZnII complexes with receptors L1 and L2[L1 = N,N, -bis(2-aminobenzyl)-1,10-diaza-15-crown-5 and L2 = N,N, -bis(2-aminobenzyl)-4,13-diaza-18-crown-6] was studied both in the solid state and in acetonitrile solution. Both receptors form mononuclear ZnII complexes in this solvent, while no evidence for the formation of dinuclear complexes was obtained. This is in contrast with previous investigations that demonstrated the formation of dinuclear complexes of L2 with first-row transition metals such as NiII, CoII and CuII. Compounds of formula [Zn(L1)](ClO4)2 (1), [Zn(L1)](NO3)2·2CH3CN (2), [Zn(L2)](ClO4)2 (3) and [Zn(L2)(NO3)2] (4) were isolated and structurally characterised by X-ray diffraction analyses. L1 forms seven-coordinate ZnII complexes in the presence of both nitrate and perchlorate anions, as a consequence of the good fit between the macrocyclic cavity and the ionic radius of the metal ion. The ZnII ion is deeply buried into the receptor cavity and the anions are forced to remain out of the metal coordination sphere. The cation [Zn(L1)]2+ present in 1 and 2 is one of the very few examples of seven-coordinate Zn complexes. Receptor L2 provides a very rare example of a macrocyclic receptor allowing endocyclic and exocyclic coordination on the same guest cation, depending on the nature of the anion present. Thus, in 3 the ZnII ion is endocyclically coordinated, placed inside the crown hole coordinated to four donor atoms of the ligand in a distorted tetrahedral environment, whereas in 4, the presence of a strongly coordinating anion such as nitrate results in an exocyclic coordination of ZnII, which is directly bound only to the two primarily amine groups of L2 and two nitrate ligands. Spectrophotometric titrations of [Zn(L2)]2+ with tetrabutylammonium nitrate in acetonitrile solution demonstrate the stepwise formation of 1:1 and 1:2 adducts with this anion in acetonitrile solution. The [Zn(L1)]2+, [Zn(L2)]2+ and [Zn(L2)(NO3)2] systems were characterised by means of DFT calculations (B3LYP model). The calculated geometries show an excellent agreement with the experimental structures obtained from X-ray diffraction analyses. Calculated binding energies of the macrocyclic ligands to ZnII are also consistent with the experimental data.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis, Complexation and Spectrofluorometric Studies of a New NS3 Anthracene-Containing Macrocyclic LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2006Abel Tamayo Abstract A new fluorescent device for detecting protons and metal ions, 11-(9-anthracenylmethyl)-1,4,7-trithia-11-azacyclotetradecane (L), has been synthesised. In addition, the photophysical properties of both the free and protonated species have been examined by absorption and fluorescence titrations of dichloromethane solutions of L with methanesulfonic acid. The coordinating properties of L toward PdII, ZnII, NiII and CoII have been studied both in solution and in the solid state. Different behaviours have been observed in the absorption and fluorescence titrations of L with the above-mentioned transition-metal ions. To evaluate whether these differences were due to the existence of equilibria between protonated and complexed species, such titrations have been repeated in the presence of an equivalent amount of acid. The structure of the [Pd(L)](BF4)2 complex has been solved by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Water-Soluble Sal2en- and Reduced Sal2en-Type Ligands: Study of Their CuII and NiII Complexes in the Solid State and in SolutionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2006Isabel Correia Abstract The CuII and NiII complexes of the Schiff base pyr2en [N,N, -ethylenebis(pyridoxyliminato)] and reduced Schiff bases Rpyr2en [N,N, -ethylenebis(pyridoxylaminato)] and R(SO3,sal)2en (SO3,sal = salicylaldehyde-5-sulfonate) were prepared and characterized by elemental analysis, IR, UV/Vis, and EPR spectroscopy. The structure of Ni(pyr2en)·3H2O was determined by single-crystal X-ray diffraction. The pyr2en2, ligand is coordinated through two phenolate-O and imine-N atoms, in a distorted square-planar geometry. The complexation of CuII and NiII with Rpyr2en in aqueous solution is studied by pH-potentiometry, UV/Vis spectroscopy, as well as by EPR spectroscopy for the CuII system, and 1H NMR spectroscopy for the NiII system. Complex formation constants were determined and binding modes proposed. While for the CuII system all complexes present a 1:1 stoichiometry with different protonation states, for the NiII system the 2:1 (L/M) complexes become important in the basic pH range at a higher ligand excess. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Highly Symmetrical Tetranuclear Cluster Complexes Supported by p - tert -Butylsulfonylcalix[4]arene as a Cluster-Forming LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006Takashi Kajiwara Abstract Square-planar tetranuclear clusters [M4(L)(AcO)4(,4 -OH)], (M = MnII, CoII, and NiII) are synthesized using tetra-anionic p - tert -butylsulfonylcalix[4]arene (L4,) as a cluster-forming ligand. Three complexes are crystallographically isostructural, being crystallized in the triclinic crystal system with space group P. The calix[4]arene acts as a tetrakis fac -tridentate ligand through four phenoxo and four sulfonyl oxygen atoms to form square arrangement of four metal ions, which are further bridged by four chelating acetate ions and one hydroxo ion in a ,4 manner to complete the hexacoordination of each metal center. Although the whole molecule of each complex is crystallographically independent, the molecule is highly symmetrical with a pseudo-four-fold axis lying on the ,4 -OH, group. The tetranuclear clusters are stable enough to maintain the core structures even in highly dilute solution (,10 ,M), which was confirmed by mass spectroscopic study, however, bridging acetates were easily exchanged by other carboxylate chelates to form derivatives such as [M4(L)(BzO)4(OH)],. Metal,metal interactions were investigated by means of magnetic susceptibility, and it was revealed that both ferro- and antiferromagnetic interactions occur in the NiII complex depending on the bridging angles of Ni,O,Ni. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Novel Metallosupramolecular Networks Constructed from CuII, NiII, and CdII with Mixed Ligands: Crystal Structures, Fluorescence, and MagnetismEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2006Miao Du Abstract Reactions of mixed ligands succinic acid (H2suc) and bent dipyridines, such as 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) and its 4- N -donor analog (4-bpo), with inorganic CuII, NiII, and CdII salts yield three new metal-organic coordination frameworks {[Cu(suc)(3-bpo)(H2O)2]·(H2O)1.75}n (1), {[Ni(suc)(4-bpo)(H2O)2]·(H2O)5}n (3), and {[Cd2(suc)2(3-bpo)2(H2O)2]·(H2O)6.75}n (4), in which the metal centers are linked by bridging ligands 3-bpo/4-bpo and suc2, along two directions to form 2D infinite networks. The corrugated 2D nets of 1 and 4, obtained under hydrothermal conditions, align in an interdigitated manner with the presence of significant aromatic-stacking interactions to result in similar 3D architectures. The 2D sheets in 3 are extended by interlayer hydrogen bonds to afford a 3D structure. However, when succinic acid is replaced by fumaric acid (H2fum) in the reaction with 3-bpo and CuII salt, a metallacyclophane [Cu(Hfum)2(3-bpo)(H2O)]2·(3-bpo)2·(H2O)6 (2) is generated. The binuclear coordinated motifs are hydrogen-bonded to the lattice water chains to furnish a unique 3D channel-like framework, in which the guest 3-bpo molecules are accommodated. The thermal stabilities of these new materials were investigated by thermogravimetric analysis (TGA) of mass loss. The magnetic coupling in complexes 1,3 is antiferromagnetic and very small, which is as expected considering the long organic bridges between the paramagnetic centers. The solid-state luminescence properties of 4 reveal an intense fluorescence emission at 378 nm. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Stable Nickel Catalysts for Fast Norbornene Polymerization: Tuning ReactivityEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2005Juan A. Casares Abstract The air-stable complexes trans -[Ni(C6Cl2F3)2L2] (L = SbPh3, 1; AsPh3, 2; AsCyPh2, 3; AsMePh2, 4; PPh3, 5) have been synthesized by arylation of [NiBr2(dme)] (dme = 1,2-dimethoxyethane) in the presence of the corresponding ligand L (for compounds 1,4) or by ligand substitution starting from 1 (for compound 5). The structures of 1, 2, and 5 have been determined by X-ray diffraction and show an almost perfect square-planar geometry in all cases. Their catalytic activity in insertion polymerization of norbornene have been tested showing a strong dependence of the yield and molecular mass of the polymer on the ligand used and the solvent. High yield and high molecular mass values are obtained using complexes with ligands easy to displace from NiII (SbPh3 is the best) and noncoordinating solvents. Complexes 1,3 are suggested as convenient bench-catalysts to have available in the lab. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Electronic Interactions in Ferrocene- and Ruthenocene-Functionalized Tetraazamacrcocyclic Ligand Complexes of FeII/III, CoII, NiII, CuII and ZnIIEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2005Peter Comba Abstract The syntheses of ferrocene- and ruthenocene-functionalized tetraazamacrocyclic ligands and their corresponding transition metal complexes are described. Reaction of N,N, -bis(2-aminoethyl)-1,3-propanediamine (2,3,2-tet) with 1,1,-diformylferrocene and 1,1,-diformylruthenocene produces the ligands fcmac and rcmac in 81,85% yield. Examination of their CuII, NiII, CoII, ZnII and FeII/III complexes by IR, UV/Vis, EPR and Mössbauer spectroscopy as well as by electrochemical studies suggests electronic communication between the two metal centers of each complex. The molecular structure of [CuII(fcmac)(FBF3)]BF4, determined by X-ray structure analysis, is reported and shows that the distance between the two metals is 4.54 Å. Stability constants, determined by potentiometric titration, indicate that the copper(II) complexes are of similar stability as those with unfunctionalized tetraazamacrocyclic ligands (e.g. cyclam = 1,4,8,11-tetraazacyclotetradecane); stability constants of cobalt(II) complexes are about 2 log units smaller, those of nickel(II) and zinc(II) complexes are reduced by more than 10 log units. This selectivity is discussed on the basis of the structural studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Oxidation of CH3NH2 and (CH3)2NH by NiIII(cyclam)(H2O)23+ in Aqueous SolutionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2004Dror Shamir Abstract NiII(1,4,8,11-tetraazacyclotetradecane)2+, NiIIL2+, is a good electrocatalyst for the oxidation of CH3NH2 and (CH3)2NH but not of (CH3)3N. The oxidation kinetics of the amines by NiIIIL(H2O)23+ indicate that the amines are good axial ligands to the tervalent nickel complex. The complexes NiIIIL[N(CH3)iH3,i](H2O)3+ are stronger oxidants than the complexes NiIIIL[N(CH3)iH3,i]23+. The oxidation is base-catalyzed and obeys a second-order rate law in NiIIILX2. It is proposed that the key step is NiIII,L(H2O)[N(CH3)iH2,i]2+ + NiIIILX2 , LNiII,N(=CH2)(CH3)i,1H2,i + NiIIL2+ + H3O+ + 2 X. Naturally, N(CH3)3 is not oxidized by this mechanism. Of special interest is the observation that the axial ligands CH3NH2 and (CH3)2NH are oxidized by the central cation, while the cyclam ligand, which has four secondary amine groups bound to the nickel(III) ion, and axially bound pendant primary amine groups, which are covalently linked to the macrocyclic ligand, are relatively stable. This difference in the behavior of axially bound amine groups is attributed to the free rotation of the axially bound N(CH3)iH3,i ligands that is required for the oxidation to proceed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] One-Dimensional CdII Coordination Polymers: Solid Solutions with NiII, Thermal Stabilities and StructuresEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2004Dejana Vujovic Abstract Reactions of Cd(NCS)2 with 2-, 3- and 4-aminobenzonitrile ligands (2ABN, 3ABN and 4ABN respectively) have produced one-dimensional chain polymers of the general formula [M(NCS)2(ABN)2]n with the metal centres linked by double NCS, bridges. The three cadmium polymers [Cd(NCS)2(3ABN)2]n (1), [Cd(NCS)2(2ABN)2]n (2) and [Cd(NCS)2(4ABN)2]n (3) all differ in their hydrogen-bonding patterns. In terms of ABN coordination, both 1 and 2 exhibit terminal amine coordination while in 3 the ABNs are coordinated through the cyano groups. Crystalline solid solutions of 1 of general formula [Cd1,xNix(NCS)2(3ABN)2]n, containing nickel and cadmium in varying proportions, have also been prepared in order to establish the influence of the metal ratio on the thermal stability and bonding parameters of the polymers. The coordination polymers are not good candidates for forming clathrates while their thermal stability (ranging between 147 and 244 °C) depends on the position of functional groups on the ABN ligands and on the Cd:Ni ratio in the solid solutions. The new polymers have been characterised by single crystal X-ray diffraction, X-ray powder diffraction, electron microscopy, infrared spectroscopy, thermogravimetry and differential scanning calorimetry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Funnel Complexes with CoII and NiII: New Probes into the Biomimetic Coordination Ability of the Calix[6]arene-Based Tris(imidazole) SystemEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2004Olivier Sénèque Abstract The coordination properties of the calix[6]arene-based tris(imidazole) ligand X6Me3Imme3 were further explored with CoII and NiII. This imidazole system stabilizes tetrahedral mononuclear CoII complexes with an exchangeable fourth exogenous ligand (water, alcohol, amide) located at the heart of the hydrophobic calixarene cavity. With a weak donor ligand such as a nitrile, both four-coordinate tetrahedral and five-coordinate trigonal bipyramidal complexes were obtained. The latter contains a second nitrile molecule trans to the included guest nitrile. These complexes were characterized in solution as well as in the solid state. The NiII complexes are square-based pyramidal five-coordinate edifices with a guest nitrile inside the cavity and a water molecule outside. A comparison with previously described ZnII and CuII complexes emphasizes the flexibility of this ligand. A comparison with carbonic anhydrase, a mononuclear zinc enzyme with a tris(histidine) coordination core, shows that X6Me3Imme3 displays many structural features of this enzyme except for the cis coordination of the exogenous ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] New Pentadentate Carboxylate-Derivatized Sulfur Ligands Affording Water Soluble Iron Complexes with [Fe(NS4)] Cores that Bind Small Molecules (CO, NO, PMe3) as Co-LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2004Dieter Sellmann Abstract In the search for polydentate sulfur ligands that are able to form water-soluble iron complexes which can bind nitrogenase relevant molecules, the new pentadentate ligands pyCO2MeS4,H2 [2,6-bis[2-mercapto-3-(methoxycarbonyl)phenylthio]dimethylpyridine] (1) and pyCO2HS4,H2 [2,6-bis(2-mercapto-3-carboxyphenylthio)dimethylpyridine] (2) having NS4 donor atom sets and terminal thiolate donors have been synthesized. The starting material was CO2MeS2,H2 (2,3-dimercapto benzoic acid methyl ester) which was alkylated with 2,6-bis[(tosyloxy)methyl]pyridine. The problem of specifically achieving regioselective mono-alkylation of this 1,2-benzene-dithiol derivative was solved by carrying out the alkylation of CO2MeS2,H2 at ,78 °C in the presence of stoichiometric amounts of a base. Saponification of 1 afforded the carboxylic acid derivative. Coordination of pyCO2MeS42, to FeII in the presence of co-ligands (L = CO, PMe3) yielded the complexes [Fe(L)(pyCO2MeS4)] where L = CO (5) or PMe3 (4). Upon treatment with NOBF4, complex 5 afforded [Fe(NO)(pyCO2MeS4)]BF4 (7) which could be subsequently converted to the isolable 19 valence electron species [Fe(NO)(pyCO2MeS4)] (8) upon reduction with N2H4. In the absence of potential co-ligands, coordination of pyCO2MeS42, to FeII afforded the dinuclear complex [Fe(pyCO2MeS4)]2 (6) whilst coordination to NiII gave [Ni(pyCO2MeS4)]x (3). Solubility of these complexes in water could be achieved by replacing the CO2Me groups with CO2H substituents. The ligand pyCO2HS42, afforded the iron complexes [Fe(L)(pyCO2HS4)] [L = CO (10) and PMe3 (12)] and [Fe(NO)(pyCO2HS4)]BF4 (11). Both 10 and 12 could be reversibly deprotonated to give the corresponding water-soluble salts (NMe4)2[Fe(L)(pyCO2S4)] with L = CO {(NMe4)2 [9]} and PMe3 {(NMe4)2 [13]}. The complexes were characterized by elemental analysis, spectroscopic methods and X-ray structural determinations. The molecular structure of [Fe(PMe3)(pyCO2HS4)] (12) was found to exhibit inter- and intramolecular O,H···O and O,H···S hydrogen bonds which serve as models for proton transfer steps from external sources to the active sites of metal sulfur enzymes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Self-Organization of Dipolar 4,4,-Disubstituted 2,2,-Bipyridine Metal Complexes into Luminescent Lamellar Liquid CrystalsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2003Daniela Pucci Abstract Mononuclear cis -dichloro complexes, [LnMCl2], with different metal centres (PtII, NiII, and ZnII) and a series of palladium and platinum derivatives, [L2MX2], in which chloride groups are replaced with iodide, bromide, and azide ligands, have been synthesized from 4,4,-disubstituted-2,2,-bipyridines. Upon complexation of these non-mesogenic ligands, the peculiar structural arrangement, characterized by intermolecular associations of the new derivatives, induces mesomorphism in most [L2MX2] complexes, confirming the importance of coordination chemistry in metal-mediated formation of liquid crystals. Single crystal X-ray structures have been determined for dihexadecyl 2,2,-bipyridyl-4,4,-dicarboxylatopalladium and -zinc dichloride derivatives. Both the metal centres and the ancillary ligands have been varied to use dipole coupling as a tool to control molecular architecture: thermal, as well as spectroscopic properties, depend strongly upon molecular dipolar interactions. Tunable red and blue emitters based on PdII and PtII, both in solution and in the solid state, have been obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Synthesis and Molecular Structures of Nickel(II) and Cobalt(III) Complexes with 2-(Arylimino)-3-(hydroxyimino)butaneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2003Ennio Zangrando Abstract We report new series of NiII and CoIII complexes with nitrogen-donor chelating ligands of the (E,E)-2-(arylimino)-3-(hydroxyimino)butane type (Ar,N,N,OH). These ligands are characterized by a hydrophilic (OH group) and a hydrophobic region (aryl group). NiII derivatives were obtained either as trimers of formula [Ni3(Ar,N,N,OH)3Br4(OH)][Br], with the hydrophobic groups oriented on the same side, or as bis(chelated) derivatives with cis geometry, depending on the steric hindrance of the aryl groups. CoIII complexes were obtained only as bis(chelated) derivatives, with the two ligands coplanar. The "iso -oriented" arrangement of ligands in bis(chelated) CoIII complexes is favored by weak interactions between the two ligands, namely O,H···O hydrogen bond and stacking interactions between the aryl groups. CoIII complexes might find application as catalysts for living or controlled radical polymerization of polar olefins, and preliminary results are reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Cyanide-Bridged Oligonuclear Complexes Containing Ni-CN-Cu and Pt-CN-Cu LinkagesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2003Marie-Louise Flay Abstract The central building blocks Ni(CN)42, and Pt(CN)42, can be combined with one, two or four CuIIL units (L = tren, Me6tren, tpa) to form di-, tri- and pentanuclear complexes with Ni-CN-Cu and Pt-CN-Cu linkages. Structure determinations of these and the side product [(tren)Cu,CN,Cu(tren)] (ClO4)2 reveal mostly linear M-C-N-Cu arrays and cis -, trans - and star-like arrangements of the CN-Cu units around the central Ni or Pt ions. The (CN) IR data for the bridging cyanides show a characteristic hypsochromic effect compared to the data for the free M(CN)42, complexes. The absorption bands in the visible spectra of the oligonuclear complexes are shifted to shorter wavelengths than those of the free LCuII -X complexes. The CuII/CuI redox steps in the cyclic voltammograms allow the conclusion that there is electronic communication between the external CuL units when they are arranged in a trans -orientation at PtII, but not NiII, centers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Direct Amination of meso -Tetraarylporphyrin Derivatives , Easy Route to A3B-, A2BC-, and A2B2 -Type Porphyrins Bearing Two Nitrogen-Containing Substituents at the meso -Positioned Phenyl GroupsHELVETICA CHIMICA ACTA, Issue 10 2007Stanis, aw Ostrowski Abstract meso -Tetraarylporphyrinato complexes 1a,g (ZnII, CuII, and NiII) bearing one or two nitro-substituted aryl moieties react with 1,1,1-trimethylhydrazinium iodide in the presence of tBuOK in THF at 0,5° or in the presence of KOH in DMSO at 60,70° according to a nucleophilic substitution of an H-atom, thus affording porphyrins 2a,g and 3f,g with amino-functionalized meso -positioned aryl substituents in yields up to 73% (Scheme,1 and Table). The products obtained are attractive intermediates for further derivatization of porphyrins and may be of potential use as sensitizers in photodynamic cancer therapy. [source] Binding Studies of Asymmetric Pentacoordinate Copper(II) Complexes Containing Phenanthroline and Ethane-1,2-diamine Ligands with Calf-Thymus DNAHELVETICA CHIMICA ACTA, Issue 9 2005Farukh Arjmand New chiral complexes of the composition [MLL,], where HL=1,2-bis(1H -benzimidazol-2-yl)ethane-1,2-diol=H2bimedol, M=CoII, NiII, CuII, and L,=1,10-phenanthroline (phen) or ethane-1,2-diamine (en), were synthesized and characterized. The ligand L exhibited a coordination mode involving the O-atom of only one OH group, the other one being directed away from the metal center. The complexes [Cu(Hbimedol)(en)]Cl (1), [Cu(Hbimedol)(phen)]Cl (2), [Co(Hbimedol)(phen)]Cl (3), [Ni(Hbimedol)(en)]Cl (4), and [Ni(Hbimedol)(phen)]Cl (5) were ionic in nature and stable at room temperature. The donor sets involved in coordination with the metal ions were the O-atom of one OH group and two N-atoms of the two benzimidazole moieties, besides the two N-atoms of phen or en (Fig.,1.). The proposed five-coordinate geometry of 1,5 was established by analysis of spectroscopic data; the ball-and-stick models supported the proposed structures of 1,5 since they showed apparently no strain on any bond and angle. The interaction of complexes 1 and 2 with calf-thymus DNA were carried out by UV/VIS titration, circular dichroism, electrochemical methods, and viscometry. The intrinsic binding constant Kb of 1 and 2 was determined as 1.57,104 and 1.51,104,M,1, respectively, suggesting that both complexes bind strongly to calf-thymus DNA. [source] Structure, Characterization, and Metal-Complexation Properties of a New Tetraazamacrocycle Containing Two Phenolic Pendant ArmsHELVETICA CHIMICA ACTA, Issue 10 2004Xiuling Cui The new tetraazamacrocycle 2 (=2,2,-[[7-Methyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene-3,11-diyl]bis(methylene)]bis(4-bromophenol)) was synthesized and used as a ligand for different metal-ion complexes. The X-ray crystal structures of the complexes of the general formula [M(H- 2)]+NO,MeOH (M=Ni2+, Zn2+), in which only one of the two pendant phenolic OH groups of 2 is deprotonated, were determined. In both complexes, the coordination environment is of the [5+1] type, the four N-atoms of the macrocyclic framework defining a square-planar arrangement around the metal center, with similar NiN and ZnN distances of 1.961(9) to 2.157(9),Å and 2.021(9) to 2.284(8),Å, respectively. In contrast, the MO distances are markedly different, 2.060(6) and 2.449(8),Å in the NiII complex, and 2.027(7) and 2.941(9),Å in the ZnII complex. The UV/VIS spectra of the NiII and CuII complexes with ligand 2, and the EPR spectra of the CuII system, suggest the same type of structure for the complexes in solution as in the solid state. Theoretical studies by means of density functional theory (DFT) confirmed the experimental structures of the NiII and ZnII complexes, and led to a proposal of a similar structure for the corresponding CuII complex. The calculated EPR parameters for the latter and comparison with related data support this interpretation. The singly occupied molecular orbital (SOMO) in these systems is mainly made of a d orbital of Cu, with a strong antibonding (,*) contribution of the axially bound phenolate residue. [source] Cyanide-Bridged CrIII,NiII Superparamagnetic Nanoparticles,ADVANCED MATERIALS, Issue 10 2003L. Catala Using reverse micelles as nanoreactors facilitates the preparation of bimetallic CrIII,NiII cyanide-bridged nanoparticles that behave as superparamagnets with a blocking temperature of 5.5 K. The Figure presents a plot of magnetization vs. field for various temperatures. Redispersion in an organic solution allows the particles to be diluted in a polymer matrix (inset of Figure) leading to a shift of the blocking temperature down to 2 K. [source] Complexation of late transition metal(II) ions (M,=,Co, Ni, Cu, and Zn) by a macrocyclic thiacrown ether studied by means of electrospray ionization mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2009Nikos G. Tsierkezos Electrospray ionization mass spectrometry (ESI-MS) is used to probe the metal-binding selectivity of a macrocyclic thiacrown ether (C44H32S20) towards CoII, NiII, CuII, and ZnII. In homogeneous 1:1 v/v methanol/dichloromethane solutions, it is found that the thia ligand very selectively binds traces of copper even in the presence of an excess of the other metal ions. The large selectivity is ascribed to the redox-active nature of copper which enables a reduction from CuII to CuI, occurring upon ESI-MS, whereas CoII, NiII and ZnII cannot undergo similar redox reactions. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dodecanuclear-Ellipse and Decanuclear-Wheel Nickel(II) Thiolato Clusters with Efficient Femtosecond Nonlinear Absorption,ANGEWANDTE CHEMIE, Issue 25 2010Chi Zhang Prof. Von Erfolg gekrönt: Die schrittweise Koordination von zwei Arten von Thiolatliganden an ein Nickel(II)-Zentrum ergibt einen zwölfkernigen elliptischen (siehe Struktur) und zwei zehnkernige radförmige NiII -Thiolatocluster. Das wellenlängenabhängige nichtlineare optische Verhalten dieser Tiara-förmigen Chromophore wurde studiert und durch theoretische Studien untermauert. Die Ergebnisse lassen auf eine wichtige Rolle von Ni-S-,-Bindungen schließen. [source] [Bis(3,5-dimethylpyrazol-1-yl-,N2)hydro(pyrazol-1-yl-,N2)borato][(3,5-dimethylpyrazol-1-yl-,N2)dihydro(pyrazol-1-yl-,N2)borato]nickel(II)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009Jason Vachon The title compound, [Ni(C8H12BN4)(C13H18BN6)] or Bp,Tp,NiII, where Bp, is (3,5-dimethylpyrazol-1-yl)dihydro(pyrazol-1-yl)borate and Tp, is bis(3,5-dimethylpyrazol-1-yl)hydro(pyrazol-1-yl)borate, contains a divalent NiII centre bound by the chelating N atoms of the polysubstituted pyrazolylborate ligands. It is shown to lack a strong agostic B,H...Ni interaction, implying that the sixth coordination site is unoccupied in the solid state. This square-pyramidal complex is the only known crystal structure where the NiII centre is pentacoordinated while bonded exclusively to pyrazolyl units. This is of interest with respect to electrochemical and catalytic properties. [source] Nickel vanadium tellurium oxide, NiV2Te2O10ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Dong Zhang Single crystals of nickel(II) divanadium(V) ditellurium(IV) decaoxide, NiV2Te2O10, were synthesized via a transport reaction in sealed evacuated silica tubes. The compound crystallizes in the triclinic system (space group P). The Ni atoms are positioned in the 1c position on the inversion centre, while the V and Te atoms are in general positions 2i. The crystal structure is layered, the building units within a (010) layer being distorted VO6 octahedra and NiO6 octahedra. The metal,oxide layers are connected by distorted TeO4E square pyramids (E being the 5s2 lone electron pair of TeIV) to form the framework. The structure contains corner-sharing NiO6 octahedra, corner- and edge-sharing TeO4E square pyramids, and corner- and edge-sharing VO6 octahedra. NiV2Te2O10 is the first oxide containing all of the cations NiII, VV and TeIV. [source] [N,N,-Bis(salicylidene)-2,2-dimethyl-1,3-propanediaminato]nickel(II) and [N,N,-bis(salicylidene)-2,2-dimethyl-1,3-propanediaminato]copper(II)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2001Cengiz Arici In the title compounds, {2,2,-[2,2-dimethyl-1,3-propanediylbis(nitrilomethylidyne)]diphenolato-,4N,N,,O,O,}nickel(II), [Ni(C19H20N2O2)], and {2,2,-[2,2-dimethyl-1,3-propanediylbis(nitrilomethylidyne)]diphenolato-,4N,N,,O,O,}copper(II), [Cu(C19H20N2O2)], the NiII and CuII atoms are coordinated by two iminic N and two phenolic O atoms of the N,N,-bis(salicylidene)-2,2-dimethyl-1,3-propanediaminate (SALPD2,, C17H16N2O22,) ligand. The geometry of the coordination sphere is planar in the case of the NiII complex and distorted towards tetrahedral for the CuII complex. Both complexes have a cis configuration imposed by the chelate ligand. The dihedral angles between the N/Ni/O and N/Cu/O coordination planes are 17.20,(6) and 35.13,(7)°, respectively. [source] NiII and ZnII complexes of the hexadentate macrocyclic ligand cis -6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamineACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2000Paul V. Bernhardt The title pendent-arm macrocyclic hexaamine ligand binds stereospecifically in a hexadentate manner, and we report here its isomorphous NiII and ZnII complexes (both as perchlorate salts), namely (cis -6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine-,6N)nickel(II) diperchlorate, [Ni(C12H30N6)](ClO4)2, and (cis -6,13-dimethyl-1,4,8,11-tetraaza-cyclotetradecane-6,13-diamine-,6N)zinc(II) diperchlorate, [Zn(C12H30N6)](ClO4)2. Distortion of the N,M,N valence angles from their ideal octahedral values becomes more pronounced with increasing metal-ion size and the present results are compared with other structures of this ligand. [source] | |||||||||||||