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Square Planar (square + planar)
Selected AbstractsDiastereopure Cationic NCN-Pincer Palladium Complexes with Square Planar ,4 - N,C,N,O CoordinationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2006Silvia Gosiewska Abstract Neutral NCN-pincer palladium bromide complex 2 containing the monoanionic, enantiopure pincer ligand 2,6-bis{[(S)-2-hydroxymethyl-1-pyrrolidinyl]methyl}phenyl bromide (1) with bis- ortho -(S)-prolinol substituents was synthesized and isolated as a mixture of three stereoisomers [(SN,SN,SC,SC), (RN,SN,SC,SC), and (RN,RN,SC,SC)] in a 1:1:1 ratio. Upon abstraction of the bromide ion from the unresolved mixture of 2, single diastereoisomers of the cationic complexes [3]BF4 and [3]PF6, respectively, were formed with a unique,4 - N,C,N,O coordination mode of ligand 1. X-ray crystal structure determination established the intramolecular,4 - N,C,N,O coordination of 1 to palladium where the typical mer -,3 - N,C,N pincer coordination is accompanied by coordination of one of the hydroxy groups of the (S)-prolinol moieties. The water molecule that was cocrystallized in the crystal structure of [3]PF6 does not coordinate to palladium, but instead is involved in a hydrogen bonding network. The catalytic potential of both cationic complexes, [3]BF4 and [3]PF6, was tested in an aldol reaction of aldehydes with methyl isocyanoacetate to yield the oxazoline products as racemic mixtures.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Rh(I) and Pd(II) complexes of methoxy functionalized heterocyclic carbene: Synthesis and characterizationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2006M. E. Günay Abstract A new methoxy functionalized 2-(trichloromethyl)-1,3-diarylimidazolidin (6) was synthesized as the precursor for N-heterocyclic carbene complexes of Pd(II) and Rh(I) by the condensation of N,N'-bis(2,4-dimethoxyphenyl)-1,2-diaminoethane with chloral. The structures of all compounds have been elucidated by a combination of multinuclear NMR spectroscopy, elemental analysis and in one instance, by single crystal X-ray diffraction. Compound 8, C27H34N2O4ClRh, crystallizes in the triclinic space group P-1 with cell dimensions a = 9.7642(12)Å, b = 11.1914(11)Å, c = 13.0102(14)Å, , = 104.034(9)°, , = 106.658(9)°, , = 99.658(9)° with Z = 2. The molecular structure of 8 shows the geometry around the Rh metal to be a slightly distorted square planar. The crystal structure shows the formation of centrosymmetric dimers via intermolecular C-H...Cl hydrogen bonds. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Structure and conformation of a nickel complex: {2-Hydroxo-3-piperidine-1-yl-methyl-N,N,(bis-5-bromobenzylpropylenediimine)nickel(II)perchlorate}CRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2004S. M. Malathy Sony Abstract The title compound, a nickel complex [C23H26N3O2Br2Ni.(ClO4)] (CCDC 199520) crystallizes in triclinic space group P with the cell parameters a = 10.2560(4), b = 10.8231(4), c = 12.0888(5)Å, , = 99.404(1), , = 99.780(1), , = 92.252(1)° and V = 1301.49(9)Å3. The structure was solved by Patterson method and refined by full-matrix least-squares procedures to a final R = 0.0497 using 6287 observed reflections. In the complex, the piperidine ring takes chair conformation and the geometry around the Ni ion is slightly distorted square planar. The dihedral angle between the planes [N-Ni-N and O-Ni-O] is 9.4(1)°. The chelate ring containing both the nitrogen atoms adopts twisted boat conformation. The molecules in the crystal are stabilized by N-H,O and C-H,O types of hydrogen bonds in addition to a C-H,, interaction. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Efficient DNA Cleavage Induced by Copper(II) Complexes of Hydrolysis Derivatives of 2,4,6-Tri(2-pyridyl)-1,3,5-triazine in the Presence of Reducing AgentsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2007Joaquín Borrás Abstract The reaction of 2,4,6-tri(pyridyl)-1,3,5-triazine (ptz) and copper(II) salts in dmf/water (1:1) results in the hydrolysis of ptz and formation of the anions bis(2-pyridylcarbonyl)amide (ptO2,) and bis(2-pyridylamine)amide (ptN2,), which are found in the complexes [Cu(ptN2)(OAc)]·3H2O (1), [Cu(ptO2)(OAc)(H2O)]·H2O (2), [Cu(ptN2)(for)]·3H2O (3) (for = formate), [Cu(ptO2)(for)(H2O)] (4), [Cu(ptO2)(benz)]·H2O (5) (benz = benzoate), and [Cu(ptO2)F(H2O)]2·3H2O (6). This report includes the chemical and spectroscopic characterization of all these complexes along with the crystal structures of 4,6. The coordination spheres of CuII in 4 and 5 are best described as distorted tetragonal square pyramidal for the former and distorted square planar for the latter. The crystal structure of 6 shows the presence of two discrete monomeric [Cu(ptO2)F(H2O)] entities in the crystallographic asymmetric unit in which both copper(II) ions have a distorted square-pyramidal coordination geometry. The binding of the complexes to DNA has been investigated with the aid of viscosity and thermal denaturation studies, both of which indicate that the interaction is probably due to the outer-sphere mechanism. The ability of the compounds to cleave DNA has also been tested. Efficient oxidative cleavage was observed in the presence of a mild reducing agent (ascorbate) and dioxygen. Mechanistic studies with reactive oxygen species (ROS) scavengers confirm that hydrogen peroxide, the hydroxyl radical, singlet oxygen-like species, and the superoxide anion are necessary diffusible intermediates in the scission process. A mechanism involving either the Fenton or theHaber,Weiss reaction plus the formation of copper oxene species is proposed for the DNA cleavage mediated by these compounds.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis of polymer-supported metal-ion complexes and evaluation of their catalytic activitiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008K. C. Gupta Abstract Polymer-supported transition-metal-ion complexes of the N,N,-bis(o -hydroxy acetophenone) propylenediamine (HPPn) Schiff base were prepared by the complexation of iron(III), cobalt(II), and nickel(II) ions on a polymer-anchored N,N,-bis(5-amino- o -hydroxy acetophenone) propylenediamine Schiff base. The complexation of iron(III), cobalt(II), and nickel(II) ions on the polymer-anchored HPPn Schiff base was 83.44, 82.92, and 89.58 wt%, respectively, whereas the unsupported HPPn Schiff base showed 82.29, 81.18, and 87.29 wt % complexation of these metal ions. The iron(III) ion complexes of the HPPn Schiff base showed octahedral geometry, whereas the cobalt(II) and nickel(II) ion complexes were square planar in shape, as suggested by spectral and magnetic measurements. The thermal stability of the HPPn Schiff base increased with the complexation of metal ions, as evidenced by thermogravimetric analysis. The HPPn Schiff base showed a weight loss of 51.0 wt % at 500°C, but its iron(III), cobalt(II), and nickel(II) ion complexes showed weight losses of 27.0, 35.0, and 44.7 wt % at the same temperature. The catalytic activity of the unsupported and supported metal-ion complexes was analyzed by the study of the oxidation of phenol and epoxidation of cyclohexene in the presence of hydrogen peroxide. The supported HPPn Schiff base complexes of iron(III) ions showed a 73.0 wt % maximum conversion of phenol and 90.6 wt % epoxidation of cyclohexene, but unsupported complexes of iron(III) ions showed 63.8 wt % conversion of phenol and 83.2 wt % epoxidation of cyclohexene. The product selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was 93.1 wt % and 98.1 wt % with the supported HPPn Schiff base complexes of iron(III) ions, but it was low with the supported Schiff base complexes of cobalt(II) and nickel(II) ions. The selectivity for CTL and ECH varied with the molar ratio of the metal ions but remained unaffected by the molar ratio of hydrogen peroxide to the substrate. The energy of activation for the epoxidation of cyclohexene and oxidation of phenol with the polymer-supported Schiff base complexes of iron(III) ions was 10.0 and 12.7 kJ/mol, respectively, but it was found to be higher with the supported HPPn Schiff base complexes of cobalt(II) and nickel(II) ions and with the unsupported HPPn Schiff base complexes of iron(III), cobalt(II), and nickel(II) ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] Catalytic activities of polymer-supported metal complexes in oxidation of phenol and epoxidation of cyclohexenePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2008K. C. Gupta Abstract The metal complexes of N, N,-bis (o -hydroxy acetophenone) propylene diamine (HPPn) Schiff base were supported on cross-linked polystyrene beads. The complexation of iron(III), copper(II), and zinc(II) ions on polymer-anchored HPPn Schiff base was 83.4, 85.7, and 84.5,wt%, respectively, whereas the complexation of these metal ions on unsupported HPPn Schiff base was 82.3, 84.5, and 83.9,wt%. The iron(III) complexes of HPPn Schiff base were octahedral in geometry, whereas copper(II) and zinc(II) ions complexes were square planar and tetrahedral. Complexation of metal ions increased the thermal stability of HPPn Schiff base. Catalytic activity of metal complexes was tested by studying the oxidation of phenol and epoxidation of cyclohexene in the presence of hydrogen peroxide. The polymer-supported HPPn Schiff base complexes of iron(III) ions showed 73.0,wt% conversion of phenol and 90.6,wt% conversion of cyclohexene at a molar ratio of 1:1:1 of substrate to catalyst and hydrogen peroxide, but unsupported complexes of iron(III) ions showed 63.8,wt% conversion for phenol and 83.2,wt% conversion for cyclohexene. The product selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was 93.1 and 98.3,wt%, respectively with supported HPPn Schiff base complexes of iron(III) ions but was lower with HPPn Schiff base complexes of copper(II) and zinc(II) ions. Activation energy for the epoxidation of cyclohexene and phenol conversion with unsupported HPPn Schiff base complexes of iron(III) ions was 16.6,kJ,mol,1 and 21.2,kJ,mol,1, respectively, but was lower with supported complexes of iron(III) ions. Copyright © 2007 John Wiley & Sons, Ltd. [source] (Di- tert -butylmethylphosphane)(,2 -di- tert -butylphosphanylphosphinidene)(triphenylphosphane)platinum(0)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Antoni Konitz The crystal structure of the title compound, [Pt(C8H18P2)(C9H21P)(C18H15P)] or [(Ph3P)(tBu2PMe)Pt(,2 - tBu2PP)], contains four molecules in the asymmetric unit with slightly different conformations. The P,P distances in the tBu2PP ligands are similar for all four molecules [2.0661,(13),2.0678,(13),Å] and indicate a multiple character of the P,P bond in the tBu2PP ligand. Molecules of the asymmetric unit can be assembled into a tetrahedron that fulfils the requirements for a rhombic disphenoid. The coordination of the Pt atom in all four molecules is square planar, with r.m.s. deviations from the PtP4 planes in the range 0.03,0.05,Å. All planes of the PtP4 groups are approximately parallel to the ab plane of the unit cell. The structure represents an unusual unsymmetrical platinum phosphinidene derivative. [source] The gold(III) tetrachloride salt of L -cocaineACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2007Matthew R. Wood The title salt, methyl (1R,2R,3S,5S,8S)-3-benzoyloxy-8-methyl-8-azabicyclo[3.2.1]octane-2-carboxylate tetrachloroaurate(III), (C17H22NO4)[AuCl4], has its protonated N atom intramolecularly hydrogen bonded to the O atom of the methoxycarbonyl group [N,O = 2.755,(6),Å and N,H,O = 136°]. Two close intermolecular C,H,O contacts exist, as well as five C,H,Cl close contacts. The [AuCl4], anion was found to be distorted square planar. [source] Polymer Complexes: supramolecular assemblies and structures of poly[N -(2,-pyridyl)propenamide] complexesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2004A. T. A. Mubarak Abstract A number of new polymer complexes of palladium(II), platinum(II) and copper(II) containing homopolymer (N -(2,-pyridyl)propenamide; APH) and various anions (Cl,, Br,, I, or NO3,) have been synthesized and characterized by elemental analyses, magnetic susceptibility, electron paramagnetic resonance, IR and reflectance spectral measurements. The homopolymer shows three types of coordination behavior. In the mononuclear polymer complexes 1,6 and 9 it acts as a neutral bidentate ligand chelated through the pyridine-nitrogen and amide-oxygen atoms, whereas in the square-planar [Pd(APH)2X2] (X = Cl, Br) unidentate APH is coordinated through the pyridine-nitrogen atom alone. Under alkaline conditions APH is deprotonated in the presence of palladium(II) to form [Pd(AP)2] (10), AP being an anionic bidentate ligand and chelating through the pyridine-nitrogen and amide-oxygen atoms. The poly-chelates are of 1:1 and 1:3 (metal:homopolymer) stoichiometry and exhibit six-coordination. The polymer complexes of stoichiometric [(APH)2CuX2] contain square planar (APH)2 Cu2+ units and the anions X, are in the axial positions, giving distorted octahedral configurations. From the electron paramagnetic resonance and spectral data, the orbital reduction factors were calculated. Copyright © 2004 John Wiley & Sons, Ltd. [source] | |||||||||||||