Search results for "Ordination"
showing 10 items of 1367 documents
Not just size and shape: spherically symmetrical d5 and d10 metal ions give different coordination nets with 4,2′:6′,4″-terpyridines
2010
Functionalized 4,2′:6′,4″-terpyridine ligands have been used to provide a divergent N,N′-donor set for the formation of coordination polymers containing {Zn2(µ-OAc)4} or {Mn3(µ-OAc)4(OAc)2} scaffolds. Single-stranded coordination polymers are produced from the reactions of 4′-(4-bromophenyl)-4,2′:6′,4″-terpyridine (1) and 4′-(4-methylthiophenyl)-4,2′:6′,4″-terpyridine (2) with Zn(OAc)2·2H2O. In [Zn2(1)(OAc)4]n and [Zn2(2)(OAc)4]n, the two outer nitrogen donors of the 4,2′:6′,4″-terpyridine ligands, bind to the axial sites of {Zn2(µ-OAc)4} units to generate coordination polymer chains which are π-stacked so that the V-shaped ligand domains are interleaved. When Mn(OAc)2·4H2O is treated with …
Pressure Effect Studies on the Spin Transition of Microporous 3D Polymer [Fe(pz)Pt(CN)4]
2018
Pressure effects on the spin transition of the three-dimensional (3D) porous coordination polymer {Fe(pz)[Pt(CN)4]} have been investigated in the interval 105 Pa–1.0 GPa through variable-temperature (10–320 K) magnetic susceptibility measurements and spectroscopic studies in the visible region at room temperature. These studies have disclosed a different behavior of the compound under pressure. In the magnetic experiments, a temperature independent paramagnetic behavior has been observed under 0.4 GPa. In contrast, at room temperature and at 0.8 GPa, a complete HS-to-LS transition has been evidenced. The differences in the magnetic behavior are strongly related with the porous structure of …
Metamagnetic Behavior in [M (tvp) (NCS)2] Coordination Polymers (M = Fe(II) and Co(II); tvp = 1,2-di-(4-pyridyl)-ethylene)
1999
Abstract We report the synthesis and magnetic properties of two new coordination polymers of formula [M(tvp)(NCS)2] (M = Fe(II) and Co(II)). The magnetic data reveal the occurrence of metamagnetic behavior. Switching from bulk antiferromagnetic to ferromagnetic behavior occurs for magnetic fields greater than 1300 G (Fe(II)) and 450 G (Co(II)) at temperatures lower than 4 K. Both compounds are isomorphous. A molecular structure is suggested in the light of the magnetic properties and precedent data on related systems.
Sn<sup>IV</sup> and Zr<sup>IV</sup> Compounds of a <i>C</i>&l…
2017
This contribution describes the synthesis and structural characterization of a triaminoguanidinium (TAG)-based ligand [H6(OMe)3Limin]BF4 (1) containing imine bonds (Limin) and its reduction with a dimethylamino borane complex to the corresponding amine compound (Lamin)[H9(OMe)3Lamin]OTs (2). In solution, both ligands are C3-symmetric but crystal structures show the great influence of the reduction on the molecular structure. We show that the planar imine ligand is converted to a highly flexible compound which has nine potential coordination sites, three phenoxy and six amine donors, for binding metal ions. First solid state structures of 1:1 (metal:ligand) coordination compounds with SnIV a…
The 2-oxoglutarate binding site of prolyl 4-hydroxylase. Identification of distinct subsites and evidence for 2-oxoglutarate decarboxylation in a lig…
1984
The structure and function of the 2-oxoglutarate binding site of prolyl 4-hydroxylase was studied by assaying the inhibitory potential of 24 selected aliphatic or aromatic compounds. All except one of them inhibited the enzyme competitively with respect to 2-oxoglutarate and noncompetitively with respect to Fe2+, the Ki values ranging from 0.8 microM to over 15 mM. The Ki values for the two most effective inhibitors, pyridine 2,5-dicarboxylate and 2,4-dicarboxylate, were about 0.8 microM and 2 microM, these compounds being the most potent inhibitors of prolyl 4-hydroxylase with respect to 2-oxoglutarate known so far. Only one of the compounds tested, 2-oxoadipinate, was able to support hydr…
Copper(II) complexes of 3-aminopropanols. Synthesis and structure of (3-aminopropanolato)formatocopper(II)
1987
Abstract The crystal and molecular structure of the title compound has been determined from single-crystal X-ray data and refined to a final R value of 0.030 for 971 reflections. The compound crystallizes in the monoclinic space group P21/c with two dimeric molecules in a cell of dimensions a=856.9(1), b= 887.7(1), c=837.0(1) pm and β=99.55(1)°. The blue crystals of Cu(ap)(HCOO) (ap=3-aminopropanolato ion) are made of centrosymmetric dialkoxy bridged dimers (Cu…Cu 296.4(1) pm). The dimers are polymerized along the c axis into chains via two NHO hydrogen bonds (Cu…Cu 547.9(1) pm). These chains are joined together along the b axis by CuOCOCu bridges and NHO hydrogen bonds (Cu…Cu 462.2(1) pm…
Synthesis, Protonation and Cu II Complexes of Two Novel Isomeric Pentaazacyclophane Ligands: Potentiometric, DFT, Kinetic and AMP Recognition Studies
2008
The synthesis and coordination chemistry of two novel ligands, 2,6,9,12,16-pentaaza[17]metacyclophane (L1) and 2,6,9,12,16-pentaaza[17]paracyclophane (L2), is described. Potentiometric studies indicate that L1 and L2 form a variety of mononuclear complexes the stability constants of which reveal a change in the denticity of the ligand when moving from L1 to L2, a behaviour that can be qualitatively explained by the inability of the paracyclophanes to simultaneously use both benzylic nitrogen atoms for coordination to a single metal centre. In contrast, the formation of dinuclear hydroxylated complexes is more favoured for the paraL2 ligand. DFT calculations have been carried out to compare …
Inter- and intramolecular non-covalent interactions in 1-methylimidazole-2-carbaldehyde complexes of copper, silver, and gold
2014
Abstract Three new imidazole compounds, [CuBr2(mimc)2] (1), [Ag(mimc)2][CF3SO3] (2), and [AuCl3(mimc)] (3) (mimc = 1-methylimidazole-2-carbaldehyde), have been synthesized, structurally characterized, and further analyzed using the QTAIM analysis. The compounds exhibit self-assembled 3D networks arising from intermolecular non-covalent interactions such as metallophilic interactions, metal-π contacts, halogens–halogen interactions, and hydrogen bonds. These weak interactions have a strong impact on the coordination sphere of the metal atoms and on the packing of compounds 1, 2, and 3.
Hybrid Organic/Inorganic Molecular Materials Formed by Tetrathiafulvalene Radicals and Magnetic Trimeric Clusters of Dimetallic Oxalate‐Bridged Compl…
2003
The first examples of trimeric, dimetallic, pure oxalate-bridged complexes [ox = (C2O4)2−] have been synthesized and characterized structurally and magnetically for the two new series of crystalline molecular assemblies formulated as (TTF)4{MII(H2O)2[MIII(ox)3]2}·nH2O [for MIII = Cr; MII = Mn (1), Fe (2), Co (3), Ni (4), Cu (5) and Zn (6); for MIII = Fe; MII = Mn (7), Fe (8), Co (9), Ni (10) and Zn (11)]. Both series (Cr2M and Fe2M) are isostructural. The crystal structure of (TTF)4{Mn(H2O)2[Cr(ox)3]2}⋅14H2O (1) [monoclinic, space group C2/c (no. 15), a = 13.240(5) A, b = 19.450(5) A, c = 27.690(5) A, β = 97.63(5)°, V = 7068(3) A3 and Z = 4] shows alternating layers of the organic radical T…
Cation and Anion Coordination Chemistry of Palladium(II) with Polyazacycloalkanes. Thermodynamic and Structural Studies
1992
The interaction of PdCI2 4 - with the macrocyclic ligands of the series [3k]aneNk has been studied both in solution and in the solid state. [18]aneN6 and [21]aneN7 form both mono- and binuclear Pd2+ complexes, whose stability constants have been determined in 0.5 mol dm-3 NaCI at 298.15 K. [21]aneN7 also forms, in solution, a trinuclear species in which an amino group deprotonates to bridge two Pd2+ ions, as observed in the solid state. The crystal structure of the complexes [Pd2([18]aneN6)Cl2][CIO4]2 and [Pd3[21]aneN7)CI3][CIO4]2 ⋅ H2O have been solved by single crystal X-ray analysis. C12H30N6CI4O8Pd2: monoclinic, space group C2/m, a = 10.876(2), b = 18.117(2), c = 7.043(2) A, s = 113.78(…