- Tripodal ligands: Design of distorted coordination polyhedra in biomimetic metal complexes. Crystal structures of [Zn(SCN)(ntb)](SCN) · iPrpOH and [Fe(acac)(ntb)](ClO4)2 · 2 CH2Cl2 · iPrpOH, ntb = N-tris(2-benzimidazolylmethyl)amine
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The tripodal ligand N-tris(2-benzimidazolylmethyl)amine (ntb) was used for the preparation of zinc(II) and iron(III) complexes, [Zn(SCN)(ntb)](SCN) · iPrpOH (1) and [Fe(acac)(ntb)](ClO4)2 · 2 CH2Cl2 · iPrpOH (2). 1 has a highly distorted trigonal-bipyramidal ZnN5 coordination geometry. The donor atoms are nitrogens of one amine, three benzimidazoles and one SCN-. A striking feature of the complex is the length of the Zn-Namine bond of 2.539(6) A. The octahedral N4O2 coordination sphere of the iron in 2 is less distorted than that of the zinc in 1. The metal is surrounded by an amine and three benzimidazole nitrogens of the ligand and two oxygens of the bidentate acetylacetonate co-ligand. The Fe-O bond lengths differ by about 0.1 A. As for the unusual long Zn-N bond in 1 this is a result of a trans effect. 1 crystallizes in the space group P1 with: a = 9.530(1) A, b = 13.402(1) A, c = 13.578(2) A, α = 98.83(1), β = 95.19(1), γ = 101.21(1)°, Z = 2; 2 is also triclinic, space group P1, with: a = 9.875(6) A, b = 12.929(10) A, c = 18.635(15) A, α = 94.95(8)°, β = 101.01(6)°, γ = 111.09(4)°, Z = 2. Johann Ambrosius Barth 1996.
- Nazikkol, Cetin,Wegner, Rainer,Bremer, Johannes,Krebs, Bernt
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- Cd(II) and Zn(II) thiocyanate coordination compounds with 3-ethylpyridine: Synthesis, crystal structures and properties
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Reaction of Cd(NCS)2 and Zn(NCS)2 with 3-ethylpyridine leads to the formation of compounds of compositions M(NCS)2(3-ethylpyridine)4 (M=Cd, 1-Cd; Zn, 1-Zn) and M(NCS)2(3-ethylpyridine)2 (M=Cd, 2-Cd; Zn, 2-Zn). 1-Cd and 1-Zn are isotypic and form discrete complexes in which the metal cations are octahedrally coordinated by two trans-coordinating N-bonded thiocyanate anions and four 3-ethylpyridine co-ligands. In 2-Cd the cations are also octahedrally coordinated but linked into chains by pairs of μ-1,3-bridging anionic ligands. 2-Zn is built up of discrete complexes, in which the Zn cation is tetrahedrally coordinated by two N-bonded thiocyanate anions and two 3-ethylpyridine co-ligands. Compounds 1-Cd, 2-Cd and 2-Zn can be prepared in a pure state, whereas 1-Zn is unstable and transforms on storage into 2-Zn. If 1-Cd and 1-Zn are heated, a transformation into 2-Cd, respectively 2-Zn is observed. Luminescence measurements reveal that 1-Cd, 2-Cd and 2-Zn emit light in the blue spectral range with maxima at, respectively, 21724, 21654 and 22055 cm-1, assigned to ligand-based luminescence.
- Neumann, Tristan,Jess, Inke,Dos Santos Cunha, Cesar,Terraschke, Huayna,N?ther, Christian
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- Crystal structure solid-state cross polarization magic angle spinning 13C NMR correlation in luminescent d10 metal-organic frameworks constructed with the 1,2-bis(1,2,4-triazol-4-yl)ethane ligand
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Hydrothermal reactions of 1,2-bis(1,2,4-triazol-4-yl)ethane (btre) with copper(ll), zinc(ll), and cadmium(ll) salts have yielded the dinuclear complexes [Zn2CI4(μ2-btre)2] (1) and [Zn2Br4(μ
- Habib, Hesham A.,Hoffmann, Anke,Hopped, Henning A.,Sieinfeld, Gunther,Janiak, Christoph
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- Trimorphism of Zn(NCS)2(4-dimethylaminopyridine)2: Crystal Structures, Thermodynamic Relations, and Comparison with the Co(II) Polymorphs
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Reaction of Zn(NCS)2 with 4-dimethylaminopyridine (DMAP) leads to the formation of three polymorphic modifications of Zn(NCS)2(DMAP)2 (I-Zn, II-Zn, and III-Zn), of which only the crystal structure of I-Zn is reported in literature. In all three modifications the Zn(II) cations are tetrahedrally coordinated by two terminal N-bonded thiocyanate anions and two DMAP ligands forming discrete complexes, which differ in the dihedral angle between the DMAP ring planes and the arrangement of the complexes in the crystals. All three modifications show melting, and the thermodynamic relations and the transition behavior were investigated by temperature-dependent X-ray powder diffraction, differential scanning calorimetry, thermomicroscopy, and solvent-mediated conversion experiments. These reveal that I-Zn and II-Zn as well as II-Zn and III-Zn are related by enantiotropism, whereas I-Zn and III-Zn are related by monotropism. The thermodynamic transition temperature between I-Zn and II-Zn is much lower than that between the isotypic Co(II) modifications I-Co and II-Co reported recently.
- Neumann, Tristan,Jess, Inke,Germann, Luzia S.,Dinnebier, Robert E.,N?ther, Christian
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- Zn(NCS)2-3-cyanopyridine Coordination Compounds: Synthesis, Crystal Structures, and Thermal Properties
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The reaction of different stoichiometric amounts of Zn(NCS)2 with 3-cyanopyridine in different solvents leads to the formation of several new coordination compounds, which were structurally characterized and investigated for their thermal behavior. In Zn(NCS)2(3-cyanopyridine)4 (1) and Zn(NCS)2(3-cyanopyridine)2(H2O)2·(3-cyanopyridine)2 (2) the zinc cations are octahedrally coordinated by two terminally N-bonded thiocyanate anions and four 3-cyanopyridine (1) or two 3-cyanopyridine and two water molecules (2) within slightly distorted octahedra. Zn(NCS)2(3-cyanopyridine)2 (3) and Zn(NCS)2(3-cyanopyridine)2·(H2O)0.5 (3-H2O) also form discrete complexes but with tetrahedrally coordinated Zn cations. Upon heating compound 1 decomposes without the formation of any intermediate compound. In contrast, compound 2 loses the water molecules in the first step and transforms into compound 1. Surprisingly, upon further heating a second TG step is observed, in which compound 3 is formed as an intermediate, which is not observed if compound 1 is heated directly. The tetrahedral complex 3 melts leading to the formation of an amorphous phase. If the hemihydrate 3-H2O is heated, it transforms into 3 via melting and crystallization but there are hints that a metastable phase might form as intermediate on water removal.
- Jochim, Aleksej,Jess, Inke,N?ther, Christian
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- Zinc coordination polymers with 1-(3-aminopropyl)-imidazole as bridging bidentate unit
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The reaction of Zn(SCN)2 with one or two equivalents of 1-(3-aminopropyl)-imidazole (api) yields the coordination polymers [Zn(SCN) 2(api)]n (1) and [Zn(SCN)2(api) 2]n (2), respectively. Single-crystal X-ray diffraction analysis reveals one-dimensional polymeric chain structures for both compounds. The structure of 1 consists of tetrahedral Zn(SCN)2(api)2 units linked by one molecule 1-aminopropyl imidazole in an unsymmetric mode, i.e., each metal center is coordinated by an imidazole nitrogen as well as a nitrogen of the aminopropyl group. The metal ions in 2 display an octahedral coordination geometry with each Zn(SCN)2(api)2 unit linked by two molecules of the imidazole, thus, exhibiting two imidazole and two amino groups in the coordination sphere. The polymers were further characterized by IR-, 1H NMR- and 13C NMR-spectroscopy.
- Arnold, Ulrich,Walter, Olaf,D?ring, Manfred
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- Selective Synthesis and Thermodynamic Relations of Polymorphic Co(NCS)2-4-Dimethylaminopyridine Coordination Compounds
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Reaction of Co(NCS)2 with 4-dimethylaminopyridine (DMAP) leads to the formation of four new compounds. The crystal structures of Co(NCS)2(DMAP)2(H2O)2·2H2O (1), Co(NCS)2(DMAP)2(MeOH)2 (2) and Co(NCS)2(DMAP)2(MeCN)2 (3) consist of discrete simple solvato complexes in which the Co cations are octahedrally coordinated by two terminally N-bonded thiocyanate anions, two DMAP ligands as well as two solvato ligands. Co(NCS)2(DMAP)2 (4/II) also forms discrete complexes, but the Co cations are tetrahedral coordinated by two anionic ligands and two DMAP ligands. Upon heating, the hydrate 1 transforms into 4/II, whereas the methanol solvate 2 transforms into a new polymorphic modification of Co(NCS)2(DMAP)2 (4/I). For structure determination the corresponding Zn(NCS)2 compound was prepared that is isotypic to 4/I. Solvent mediated conversion experiments prove that 4/II represents the thermodynamic stable form at room-temperature and density functional theory (DFT) calculations indicate that this form is also stable at 0 K. Upon heating both modifications show melting with the higher melting polymorph 4/I having the lower melting enthalpy. Temperature dependent X-ray powder diffraction shows that 4/II transforms into 4/I upon heating. All experimental results indicate, that both modifications are related by enantiotropism.
- Neumann, Tristan,Jess, Inke,Pielnhofer, Florian,N?ther, Christian
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- New fluorescent compounds based on zinc thiocyanate: Influence of structure on spectral properties
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New coordination compounds based on zinc thiocyanate, namely (acetone thiosemicarbazone- κ2N1,S)bis(isothiocyanato-κN)zinc(II) monohydrate, [Zn(NCS)2- (C4H9N3S)].H2O, (I), and diaquatetrakis(urea-κO)zinc(II) tetrakis(isothiocyanato- κN)zinc(II), [Zn(CH4N2O)4(H2O)2][Zn(NCS)4], (II), were synthesized and studied by UVVis, fluorescence and IR spectroscopy. Coordination salt (II) forms a rare system composed of two different coordination units of the same metal and it is the first example of a compound with two completely different zinc coordination units, of which one contains a tetrakis(urea)zinc unit. Both (I) and (II) possess fluorescence properties and produce blue and green emissions, respectively, upon irradiation with violet light. The spectral properties were correlated with the observed molecular and supramolecular structures. The acetone thiosemicarbazone ligand of (I) exhibits (upon coordination) red shifts of bands corresponding to N=C and C=S stretching vibration frequencies, which is not typical for chelating molecules.
- Swiatkowski, Marcin,Kruszynski, Rafal
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- Synthesis, Crystal Structures, and Properties of M(NCS)2-3-aminomethylpyridine Coordination Compounds (M = Cd, Zn)
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Reaction of Cd(NCS)2 or Zn(NCS)2 with 3-aminomethylpyridine (3-AMPy) leads to the formation of five compounds with the compositions [Cd(NCS)2(3-AMPy)2·(3-AMPy)]n (1-Cd), [M(NCS)2(3-AMPy)2]n [M = Cd (2-Cd), Zn (2-Zn)] [Cd(NCS)2(3-AMPy)]n (3-Cd), and [Zn(NCS)2(3-AMPy)]2 (3-Zn). In 1-Cd the Cd cations are linked by the 3-AMPy ligands into layers that consist of rings, built up of four Cd cations and four 3-AMPy ligands. These layers are stacked to form channels, in which the 3-AMPy solvate molecules are located. In the isotypic compounds 2-Cd and 2-Zn the metal cations are also linked into layers by the 3-AMPy ligands with an identical layer topology as that in 1-Cd, but a completely different conformation of the 3-AMPy ligand. In the most 3-AMPy deficient compound 3-Cd, the Cd cations are linked by μ-1,3-bridging thiocyanate anions and 3-AMPy ligands into chains, that are further connected into layers by additional anionic ligands. In 3-Zn two Zn cations are linked by pairs of 3-AMPy ligands into discrete dimers. Thermoanalysis and X-ray powder diffraction (XRPD) investigations show that upon heating 1-Cd transforms into 2-Cd and 2-Zn into 3-Zn. The compounds 2-Cd, 3-Cd, 2-Zn, and 3-Zn present ligand-based luminescence in the blue-green spectral range with maxima between 21276 and 21795 cm–1.
- Neumann, Tristan,Germann, Luzia S.,Moudrakovski, Igor,Dinnebier, Robert E.,dos Santos Cunha, Cesar,Terraschke, Huayna,N?ther, Christian
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- The influence of the metal cation and the N-donor ligand on the reactivity and structures of Cd and Zn coordination compounds with 3-bromopyridine and 3-chloropyridine
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Reaction of cadmium thiocyanate and zinc thiocyanate with an excess of 3-bromopyridine and 3-chloropyridine leads to single crystals of four coordination compounds of composition M(NCS)2(3-bromopyridine) 4 (M = Cd (Cd1-Br), Zn (Zn1-Br)) and M(NCS)2(3- chloropyridine)4 (M = Cd (Cd1-Cl), Zn (Zn1-Cl)). These compounds forms pairs of isotypic compounds (Cd1-Br and Zn1-Br in space group P-1 and Cd1-Cl and Zn1-Cl in space group C2/c) in which the metal cation are octahedral coordinated by two terminal thiocyanato anions and four neutral N-donor ligands into discrete complexes. If less N-donor ligands are used in the synthesis, compounds of composition M(NCS)2(3-bromopyridine)2 (M = Cd (Cd2-Br), Zn (Zn2-Br)) and M(NCS)2(3-chloropyridine)2 (M = Cd (Cd2-Cl), Zn (Zn2-Cl)) are obtained. In the crystal structure of the isotypic compounds Cd2-Br and Cd2-Cl (monoclinic space group P21/c) the metal cations are octahedral coordinated by two N-donor ligands and four thiocyanato anions and are linked into chains by the anionic ligands. In contrast, the Zn compounds Zn2-Br and Zn2-Cl are not isotypic but form similar discrete complexes in which the metal cations are tetrahedral coordinated by two terminal N-bonded thiocyanato anions and two neutral N-donor ligands. On heating compounds 1 half of the ligands are removed and a transformation into compounds 2 is observed. The structures and reactivity of these compounds are discussed and compared with those of related compounds.
- W?hlert, Susanne,Jess, Inke,N?ther, Christian
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- Synthesis, crystal structures, and thermal properties of new zinc(II) thiocyanato coordination compounds
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Reaction of zinc(II) thiocyanate with pyrazine, pyrimidine, pyridazine, and pyridine leads to the formation of new zinc(II) thiocyanato coordination compounds. In bis(isothiocyanato-N)-bis(μ2-pyrazine-N,N) zinc(II) (1) and bis(isothiocyanato-N)-bis(μ2-pyrimidine-N,N) zinc(II) (2) the zinc atoms are coordinated by four nitrogen atoms of the diazine ligands and two nitrogen atoms of the isothiocyanato anions within slightly distorted octahedra. The zinc atoms are connected by the diazine ligands into layers, which are further linked by weak intermolecular S···S interactions in 1 and by weak intermolecular C-H···S hydrogen bonding in 2. In bis(isothiocyanato-N)-bis(pyridazine-N) (3) discrete complexes are found, in which the zinc atoms are coordinated by two nitrogen atoms of the isothiocyanato ligands and two nitrogen atoms of the pyridazine ligands. The crystal structure of bis(isothiocyanato-N)-tetrakis(pyridine-N) (4) is known and consists of discrete complexes, in which the zinc atoms are octahedrally coordinated by two thiocyanato anions and four pyridine molecules. Investigations using simultaneous differential thermoanalysis and thermogravimetry, X-ray powder diffraction and IR spectroscopy prove that on heating, the ligand-rich compounds 1, 2, and 3 decompose without the formation of ligand-deficient intermediate phases. In contrast, compound 4 looses the pyridine ligands in two different steps, leading to the formation of the literature known ligand-deficient compound bis(isothiocyanato-N)-bis(pyridine-N) (5) as an intermediate. The crystal structure of compound 5 consists of tetrahedrally coordinated zinc atoms which are surrounded by two isothiocyanato anions and two pyridine ligands. The structures and the thermal reactivity are discussed and compared with this of related transition metal isothiocyanates with pyrazine, pyrimidine, pyridazine, and pyridine. Copyright
- Bhosekar, Gaurav,Boeckmann, Jan,Jess, Inke,Naether, Christian
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- Synthesis, Structures, and Physical Properties of Thiocyanate Coordination Compounds with 3-Hydroxymethylpyridine
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The reaction of Cd(NCS)2 with 3-hydroxymethylpyridine (3-HMPy) leads to the formation of compounds with the composition Cd(NCS)2(3-HMPy)4 (1-Cd), Cd(NCS)2(3-HMPy)2 (2-Cd) (Cd(NCS)2)2(3-HMPy)3 (3-Cd), and (Cd(NCS)2)3(3-HMPy)4 (4-Cd). Compound 1-Cd consists of discrete complexes and in 2-Cd the Cd cations are linked into chains by the anionic and the organic co-ligands. In 3-Cd as well as 4-Cd the Cd cations are connected into chains by the thiocyanate anions, which are further linked into layers by the 3-HMPy co-ligands. In contrast, with Zn only one compound with the composition Zn(NCS)2(3-HMPy)2·H2O (1-Zn-H2O) was characterized by single-crystal X-ray diffraction, which shows a tetrahedral coordination of the Zn cations by two thiocyanate anions and two 3-HMPy ligands. The discrete complexes are arranged to form channels, in which the water molecules are embedded. 1-Zn-H2O cannot be obtained phase pure and detailed investigations reveal, that additional Zn compounds with the composition Zn(NCS)2(3-HMPy)2·xH2O including an anhydrate (1-Zn) can be obtained, which possesses a similar X-ray powder diffraction (XRPD) pattern. 1-Zn was characterized using X-ray powder diffraction analysis. Most compounds were investigated by thermoanalysis, IR and Raman as well as luminescence spectroscopy.
- Neumann, Tristan,dos Santos Cunha, Cesar,Terraschke, Huayna,Germann, Luzia S.,Dinnebier, Robert E.,Jess, Inke,N?ther, Christian
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- Investigations on the structure diversity and thermal degradation behavior of CdII and ZnII thiocyanato coordination compounds based on 3-acetylpyridine as neutral co-ligand
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Reaction of CdII and ZnII thiocyanate with 3-acetylpyridine leads to the formation of the new CdII and Zn II coordination compounds [Cd(NCS)2(3-acetylpyridine) 4] (1A), [Cd(NCS)2(3-acetylpyridine)2] n (1B), [Cd(NCS)2(3-acetylpyridine)]n (1C) and [Zn(NCS)2(3-acetylpyridine)2] (2A). Compound 1A consists of discrete complexes, in which the metal centers are octahedrally coordinated by four terminal bonded N-donor co-ligands and two terminal N-bonded thiocyanato anions. In compound 2A the metal centers are only tetrahedrally coordinated by two terminal bonded N-donor co-ligands and two terminal N-bonded thiocyanato anions. In compound 1B the CdII cations are octahedrally coordinated by two terminal bonded N-donor co-ligands and four thiocyanato anions. The metal centers are linked by μ-1, 3 bridging thiocyanato anions into chains. In compound 1C the metal cations are octahedrally coordinated by two μ-1, 5 bridging 3-acetyl-pyridine ligands and four μ-1, 3 bridging thiocyanato anions building up a three-dimensional coordination network. Investigations on the thermal degradation behavior of all compounds using simultaneous differential thermoanalysis and thermogravimetry as well as X-ray powder diffraction and IR spectroscopy prove that on heating compound 2A decompose without the formation of 3-acetylpyridine-deficient intermediates. In contrast, for compound 1A a stepwise decomposition is observed, leading to the formation of the 3-acetylpyridine-deficient compound [Cd(NCS)2(3- acetylpyridine)2]n (1B) which decomposes on further heating Copyright
- Werner, Julia,Boeckmann, Jan,Naether, Christian
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- X-Ray Diffraction, Raman, and NMR Studies on Tetrathiocyanato Complexes of Zinc(II), Cadmium(II), and Mercury(II) Ions in Aqueous Solution
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S-Ray scattering, Raman, and 13C- and 14N-NMR measurements were performed on aqueous solutions containing tetrathiocyanato complex ions of Zn(II), Cd(II), and Hg(II).The radial distribution functions revealed that four thiocyanate ions tetrahedrally coord
- Yamaguchi, Toshio,Yamamoto, Kiyoshi,Ohtaki, Hitoshi
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- An ultrasonic absorption study of the complex formation of zinc(II) thiocyanate in aqueous solution
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A new method of analysis for the ultrasonic absorption of systems involving multiple coupled equilibria is described.The method consists of calculating the relaxation frequencies and amplitudes under a postulated reaction mechanism using trial values of the rate constants and volume changes and of comparing the computed absorption α/f2 (absorption coefficient over frequency squared) directly with the experimental one.Application of this method to the ultrasonic absorption study of aqueous zinc(II)-thiocyanate solutions reveals that the relaxation absorption is ascribed to the successive complex formation equilibria .The rate constants and volume changes ofthe above reactions are determined.The method proves to be especially effective when the absorption spectra are associated with multiple coupled equilibria and accordingly too broad to be separated to discrete relaxation processes by the usual method of analysis.
- Tamura, Kiyoshi
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- Coordination-driven self-assembly of a series of dinuclear M2L2mesocates with a bis-bidentate pyridylimine ligand
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Four isostructural dinuclear M2L2mesocates of the general formula [M2(NCS)4(L)2]·4.5MeOH (1M; M = Mn, Fe, Co, Zn) were constructed by using the coordination-driven self-assembly of the [M(NCS)2] precursor and the flexible bis-bidentate pyridylimine Schiff base ligand L (L = 4,4′-(1,4-phenylenebis(oxy))bis(N-(pyridin-2-ylmethylene)aniline). The centrosymmetric M2L2mesocate forms through the side-by-side coordination of two L ligands to a pair of M(ii) ions. The mesocates exhibit a reversible temperature induced desolvation-solvation behavior without losing their structural integrity. The activated1Co, as the representative M2L2mesocate, shows an exceptionally high MeOH vapour uptake capacity of 481.9 cm3g?1(68.8 wt%) at STP with good recyclability. Notably, it also exhibits CO2adsorption with an uptake capacity of 20.2 cm3g?1(3.6 wt%) at room temperature and 1 bar.
- Chainok, Kittipong,Dungkaew, Winya,Jiajaroen, Suwadee,Jittirattanakun, Siripak,Kielar, Filip,Puangsing, Praifon,Rungtaweevoranit, Bunyarat,Saphu, Watcharin,Sukwattanasinitt, Mongkol,Theppitak, Chatphorn
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p. 7736 - 7743
(2021/06/16)
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- Supramolecular Metallacycles and Their Binding of Fullerenes
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The synthesis of a new triaminoguanidinium-based ligand with three tris-chelating [NNO]-binding pockets and C3 symmetry is described. The reaction of tris-(2-pyridinylene-N-oxide)triaminoguanidinium salts with zinc(II) formate leads to the formation of cyclic supramolecular coordination compounds which in solution bind fullerenes in their spherical cavities. The rapid encapsulation of C60 can be observed by NMR spectroscopy and single-crystal X-ray diffraction and is verified using computation.
- Ehnbom, Andreas,G?b, Christian R.,Oppel, Iris M.,Sturm, Lisa,Tobe, Yoshito
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supporting information
(2020/03/19)
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- Luminescent Zn(NCS)2 and Cd(NCS)2 coordination compounds with pyridine derivatives: Synthesis, structures and physical properties
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Reaction of Cd(NCS)2 and Zn(NCS)2 with the co-ligands 4-benzylpyridine or 4-benzoylpyridine leads to the formation of eight new compounds, of which one crystallizes in two polymorphic modifications. The co-ligand rich compounds with the composition M(NCS)2(L)4 (M = Cd, Zn and L = 4-benzylpyridine or 4-benzoylpyridine) (1) form discrete complexes, in which the metal cations are each coordinated by four co-ligands and two N-bonded anionic ligands within slightly distorted octahedra. In the co-ligand deficient compounds (2) with the composition M(NCS)2(L)2 two structure types are observed. The Zn compounds form discrete complexes in which the Zn cations are tetrahedral coordinated (2-Zn), whereas in the Cd compounds (2-Cd) the metal cations are octahedral coordinated and linked into chains by pairs of μ-1,3-bridging thiocyanate anions. Upon heating, compounds 1 loose half of the co-ligands and transform into compounds 2. The coordination mode of the anionic ligands was also investigated by IR and Raman spectroscopy. All compounds show blue-green ligand-based luminescence with emission maxima varying between 21,857 cm?1 and 18,264 cm?1.
- Neumann, Tristan,Jess, Inke,dos Santos Cunha, Cesar,Terraschke, Huayna,N?ther, Christian
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- Effect of metal dilution on the thermal spin transition of [Fe xZn1-x (bapbpy)(NCS)2]
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This study reports on the effects of zinc dilution on the structure and magnetic properties of the mononuclear two-step spin-crossover compound [Fe(bapbpy)(NCS)2] (1; bapbpy = N6,N6′-di(pyridin-2-yl)-2, 2′-bipyridine-6,6′-diamine). The zinc analogue of 1, [Zn(bapbpy)(NCS)2] (3), was synthesized and characterized by X-ray powder diffraction, which suggests different structural features from 1. The crystal structure of the related compound [Fe(bapbpy)(NCS)]2[Zn- (NCS)4]·3DMF (4) was determined by single-crystal X-ray diffraction. Unlike the hexacoordinate FeII in 1, the ZnII ions in 4 are pentacoordinate. Nine diluted powder samples [FexZn1-x (bapbpy)(NCS) 2] were prepared with iron fractions of x = 0.89, 0.81, 0.76, 0.65, 0.60, 0.53, 0.44, 0.38, and 0.24. According to powder X-ray diffraction and infrared spectroscopy, the phase of compound 1 is retained in the zincdiluted samples when x > 0.53. At higher dilutions (i.e., when x a single-step SCO material at x = 0.76. Upon additional increase of the zinc contents, the cooperativity of the SCO gradually vanishes to lead to a noncooperative SCO material at the lowest iron fraction studied (x = 0.24). Despite the different coordination properties of the bapbpy ligand towards FeII and ZnII, the spin crossover of the hexacoordinate FeII complex is robust enough to withstand dilution into a magnetically silent ZnII phase that is structurally different from that of the iron compound.
- Zheng, Sipeng,Siegler, Maxime A.,Costa, Jose Sanchez,Fu, Wen-Tian,Bonnet, Sylvestre
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p. 1033 - 1042
(2013/06/27)
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- Microwave-assisted synthesis of alkyl thiocyanates
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Microwave irradiation accelerated the reaction of t-alkyl, allyl, and benzyl halides with Zn(SCN)2 to afford thiocyanates in excellent yields and high selectivity with the formation of isothiocyanates only in minor proportions. Because thiocyanates are stable intermediates to thiols, the method also affords facile access to corresponding thiols.
- Bound, D. James,Bettadaiah,Srinivas
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p. 1138 - 1144
(2013/03/28)
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- Large-ring chain and sheet polymeric metal complexes of extended-reach siloxypyridine ligands of type O[iPr2SiO(CH2)npy]2
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The preparations are reported of a range of metal complexes of Mn(II), Co(II), Ni(II) and Zn(II) with the 'extended reach' ligands O[iPr2SiO(CH2)npy]2 (n=0, 1 or 3, I-III) and with Cu(II), Cd(II) and Ag(I) for II; six of them have been shown by X-ray studies to have polymeric structures. The compounds M[O(iPr2SiOpy)2]2Cl2 (M=Co, Cu) form chains of 24-membered macrocycles, as does Co[O(iPr2SiOCH2py)2] 2I2(H2O)2. A similar structure is formed by Mn[O(iPr2SiOCH2py)2] 2Cl2 but in this case the rings are 28-membered. The complex Cu[O(iPr2SiOpy)2]Cl2 forms sheets of 52-membered macrocycles with chloride bridged Cu2Cl4 units at the node points. The structure of Cu2[O(iPr2SiOpy)2]4Cl 3 comprises sheets of 48-membered rings which are linked into pairs of sheets by linear, but weak, Cu-Cl-Cu bridges. X- and Q-band EPR spectra of the manganese compounds are also reported, as are relevant spectroscopic results for the other complexes.
- Goodgame, David M.L.,Lickiss, Paul D.,Rooke, Stephanie J.,White, Andrew J.P.,Williams, David J.
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- Thiocyanates. 1: N-H(N)...S bonding in tetrahedral [zn(NCS)2L]0 complexes (L = MexH2-xN(CH2)2NH 2-yMey, x, y = 0-2)
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The crystal structures of uncharged tetrahedral dithiocyanato zinc complexes with N-methylated ethylenediamines have been determined with a view to a study of intermolecular hydrogen-bonding interactions in these compounds. It is found that the H(N) hydrogen atoms are exhaustively engaged in N-H(N) ... S bonds. The majority of these bonds are branched (bifurcated or trifurcated), and the hydrogen-bond systems they form all contain one of the two characteristic primitive core motifs: either a discrete centrosymmetric [...S...H...]2 dimer or an infinite [...S...H...]∞ helix about a 21 or pseudo-21 axis. The hydrogen bonding is analyzed in detail, with particular attention to the existence of correlations between the N-H(N)-S angles and the H(N) ... S distances as well as between the corresponding N-H(N)-S/H(N) ... S pairs in the bifurcated N-H(N) ... 2S bonds.
- Cameron, Elinor M.,Louch, William E.,Cameron, T. Stanley,Knop, Osvald
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p. 1629 - 1641
(2008/10/09)
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- Studies on tetrametallic complexes of 1, 1'-bis(thiocyanatomercurio)ferrocene
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Cu(Salen) and Zn(Salen) have been reacted with Fe(C5H4HgSCN)2M(NCS)2 and adducts having four different metals have been prepared.The various physicochemical studies indicate that Cu(Salen) and Zn(Salen) act as bidentate ligands coordinating through phenolic oxygen.The geometry, where M is Co(II), Mn(II), Zn(II), changes from tetrahedral in the Lewis acids to octahedral in adducts.
- Singh, P. P.,Singh, Deepa,Singh, A. P.
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p. 472 - 475
(2007/10/02)
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- Nicotine Complexes of Zinc(II), Cadmium(II) and Mercury(II)
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Complexes of nicotine(nic), M(nic)nX2 (M = Zn or Cd; n = 2, X = Cl, Br, I or NCS; M = Hg, n = 1, X = Cl, Br or I) have been prepared.The conductivity measurements indicate that the complexes are nonionic.The complexes have been characterised on the basis of analytical, IR and PMR spectral, and thermal studies.
- Muralidharan, S.,Udupa, M. R.,Nagaraja, K. S.
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- Bimetallic Complexes involving Schiff Base
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Phenylmercury derivative (phHgSA) of Schiff base SAH derived from salicylaldehyde and aniline have been prepared.Reaction of this derivative with M(NCS)2, where M=CoII, NiII, CuII and ZnII, gave complexes of general formula (phHgSA)2M(NCS)2.These complexes on further reaction pyridine or bipyridine (L) furnished adducts of general formula (phHgSA)2M(NCS)2Lx, where x=1 or 2.All the complexes have been characterised by elemental analysis, molecular weight, molar conductance, infrared and electronic spectral data.On the basis of these studies, probable structure of the complexes and quantitative softness parameters have been evaluated.
- Singh, P. P.,Srivastava, Beena
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p. 797 - 800
(2007/10/02)
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