Search results for "Octahedron"
showing 10 items of 405 documents
Coordinating behaviour of a new pyridylhydrazone; tris-complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) with 2-pyridylcarb…
1991
The preparation and characterization oftris-complexes of MnII, CoII, NiII, CuII and ZnII with a new pyridylhydrazone, 2-pyridylcarbaldehyde-N,N-dimethylhydrazone (pch), are described. In all the complexes pch behaves as a bidentate ligand binding through the pyridine and azomethyne nitrogen atoms. The complexes appear to be monomeric, high spin six-coordinate, and a distorted octahedral stereochemistry around the metal is suggested. The e.p.r. results for both CuII compounds indicate a mainly dx2−y2 ground state with a static Jahn-Teller distortion, whilst for the MnII complex the e.p.r. data indicates a very low symmetry for the MnN6 polyhedron.
Synthesis and Spectroscopic Characterisation ofbis-Complexes of Cobalt(II), Nickel(II) and Copper(II) with N,N,N′N′-Tetraethylpyridinecarboxamide
1994
Abstract Bis-complexes of Co(II), Ni(II) and Cu(II) with tedpa (N,N,N′N′-tetraethyl-pyridinedicarboxamide) having the general formula [M(tedpa)2]X2 (X = ClO4, PF6) have been synthesized and characterised by i.r., electronic and e.p.r. spectra. The spectroscopic results suggest that the tedpa acts in these compounds as tridentate ligand through two oxygen atoms and a nitrogen (from the pyridine ring) atom. A distorted octahedral environment (MN2O4 chromophores) for the metal atoms is inferred from the spectroscopic data.
Synthesis, X-ray crystal structure and magnetic study of a dicyanamido bridged 1D chain nickel(II) complex
2008
Abstract Reaction of Ni(NO3)2 · 6H2O and sodium dicyanamide (Nadca) yields a 1D infinite chain complex {[Ni(dien)(μ1,5-dca)(H2O)](NO3)}n (1) (where dien = diethylenetriamine). The coordination environment in complex 1 around the nickel(II) ions is distorted octahedron. Three nitrogen atoms of the ligand diethylenetriamine and an oxygen atom of H2O molecule constitute the four coordination sites of the basal plane of the octahedron. Of two axial positions of the octahedron, one position is occupied by the nitrogen atom of a μ1,5-dca anion the remaining coordination site is occupied by a nitrogen atom of another end-to-end bridging dca from an adjacent [Ni(dien)(μ1,5-dca)(H2O)] moiety, yieldi…
Ligand substitution in hexahalorhenate(IV) complexes: Synthesis, crystal structures and magnetic properties of NBu4[ReX5(DMF)] (X=Cl and Br)
2006
Abstract The preparation, crystal structures, and magnetic properties of two rhenium(IV) mononuclear compounds of formula NBu 4 [ReX 5 (DMF)] ( NBu 4 + = tetrabutylammonium cation and DMF = N , N - dimethylformamide ) with X = Cl ( 1 ) and Br ( 2 ) are reported. 1 and 2 are isostructural complexes which crystallize in the monoclinic system with the space group P 2 1 / n . The rhenium atom is six-coordinated with five X atoms and a DMF molecule forming a somewhat distorted octahedral surrounding [values of Re–X varying in the ranges 2.317(1)–2.358(1) ( 1 ) and 2.495(1)–2.518(1) A ( 2 )]. Magnetic susceptibility measurements on samples of 1 and 2 in the temperature range 1.9–300 K are interpr…
Synthesis, Structure, and Magnetic Properties of Regular Alternating μ-bpm/di-μ-X Copper(II) Chains (bpm = 2,2′-bipyrimidine; X = OH, F)
2012
The preparation and X-ray crystal structure of four 2,2'-bipyrimidine (bpm)-containing copper(II) complexes of formula {[Cu(2)(μ-bpm)(H(2)O)(4)(μ-OH)(2)][Mn(H(2)O)(6)](SO(4))(2)}(n) (1), {[Cu(2)(μ-bpm)(H(2)O)(4)(μ-OH)(2)]SiF(6)}(n) (2), {Cu(2)(μ-bpm)(H(2)O)(2)(μ-F)(2)F(2)}(n) (3), and [Cu(bpm)(H(2)O)(2)F(NO(3))][Cu(bpm)(H(2)O)(3)F]NO(3)·2H(2)O (4) are reported. The structures of 1-3 consist of chains of copper(II) ions with regular alternation of bis-bidentate bpm and di-μ-hydroxo (1 and 2) or di-μ-fluoro (3) groups, the electroneutrality being achieved by either hexaaqua manganese(II) cations plus uncoordinated sulfate anions (1), uncoordinated hexafluorosilicate anions (2), or terminally …
Magnetic properties of AgLnSe2 compounds (Ln=Ho, Er, Tm and Yb)
2001
Abstract The heavy lanthanide selenides AgLnSe2 (Ln=Ho–Yb) crystallize in the orthorhombic AgErSe2 type structure (P212121). The lanthanide ions are placed in the centres of slightly distorted octahedra, whereas each of the silver ions is surrounded by four selenide ions forming a strongly distorted tetrahedron. The high field magnetization (up to 14 T) and the magnetic susceptibility were measured on the polycrystalline samples. The crystal field parameters were estimated from the field dependences of the magnetizations, assuming a rhombic distortion of LnSe6 octahedra. The magnetic susceptibilities were also calculated using the same set of the crystal field parameters. None of the compou…
Custom coordination environments for lanthanoids: tripodal ligands achieve near-perfect octahedral coordination for two dysprosium-based molecular na…
2017
Controlling the coordination sphere of lanthanoid complexes is a challenging critical step toward controlling their relaxation properties. Here we present the synthesis of hexacoordinated dysprosium single-molecule magnets, where tripodal ligands achieve a near-perfect octahedral coordination. We perform a complete experimental and theoretical investigation of their magnetic properties, including a full single-crystal magnetic anisotropy analysis. The combination of electrostatic and crystal-field computational tools (SIMPRE and CONDON codes) allows us to explain the static behavior of these systems in detail. NRF-2015R1A2A1A10055658 Grant NRF-2012-0008901 NRF2010-0020209 ERC-CoG-647301 DEC…
New 3d–4f supramolecular systems constructed by [Fe(bipy)(CN)4]− and partially blocked lanthanide cations
2009
Abstract The reaction of acetonitrile (1–5) and mixed acetonitrile/water 1:1 (6–9) solutions containing the cyanide-bearing [Fe(bipy)(CN)4]− building block (bipy = 2,2′-bipyridine) and the partially blocked [Ln(bpym)]3+ cation (Ln = lanthanide trivalent cation and bpym = 2,2′-bipyrimidine) has afforded two new families of 3d–4f supramolecular assemblies of formula [Ln(bpym)(NO3)2(H2O)3][Fe(bipy)(CN)4] · H2O · CH3CN [Ln = Sm (1), Gd (2), Tb (3), Dy (4) and Ho (5)] and [Ln(bpym)(NO3)2(H2O)4][Fe(bipy)(CN)4] [Ln = Pr (6), Nd (7), Sm (8), Gd (9)]. They crystallize in the P21/c (1–5) and P2/c (6–9) space groups and their structures are made up of [Fe(bipy)(CN)4]− anions (1–9) and [Ln(bpym)(NO3)2(…
[Fe(phen)(CN)4]−: a suitable metalloligand unit to build 3d–4f heterobimetallic complexes with mixed bpym-cyano bridges (phen = 1,10-phenantroline, b…
2010
The synthesis, crystal structure and magnetic properties of a new series of mixed 3d–4f complexes with the formula [{FeIII(phen)(CN)3(μ-CN)}4Ln2III(NO3)2(H2O)6(μ-bpym)]·nH2O [Ln = Eu (1), Gd (2), Dy (3) and Ho (4); n = 8 (1, 3 and 4) and 11 (2); phen = 1,10-phenantroline; bpym = 2,2′-bipyrimidine] are discussed here. Compounds 1–4 are centrosymmetric hexanuclear species whose structure is made up of two cyano-bridged {Fe2IIILnIII} heterobimetallic moieties which are connected through a bis-bidentate bpym molecule between the two rare-earth centers. The values of the iron–lanthanide distance across the single cyano-bridge are Fe(1)⋯Eu(1) = 5.5587(8) and Fe(2)⋯Eu(1) = 5.4908(8) A (1), Fe(1)⋯G…
The construction of open GdIII metal–organic frameworks based on methanetriacetic acid: New objects with an old ligand
2010
11 páginas, 11 figuras, 2 esquemas.-- et al.