Search results for "Octahedron"
showing 10 items of 405 documents
Mononuclear Fe(III) and tetranuclear [Fe(III)Gd(III)]2 complexes with a Schiff-base ligand derived from the o-vanillin: Synthesis, crystal structures…
2011
The mononuclear high-spin iron(III) complexes [Fe(3-MeOsalpn)Cl(H 2 O)] ( 1 ) and [Fe(3-MeOsalpn)(NCS)(H 2 O)]·0.5CH 3 CN ( 2 ) and the tetranuclear oxo-bridged compound [{Fe(3-MeOsalpn)Gd(NO 3 ) 3 } 2 (μ-O)]·CH 3 CN ( 3 ) [3-MeOsalpn 2− = N , N ′-propylenebis(3-methoxysalicylideneiminate)] have been prepared and magneto-structurally characterised. The iron(III) ion in 1 and 2 is six-coordinated in a somewhat distorted octahedral surrounding with the two phenolate-oxygens and two imine-nitrogens from the Schiff-base building the equatorial plane and a water ( 1 and 2 ) and a chloro ( 1 )/thiocyanate-nitrogen ( 2 ) in the axial positions. The neutral mononuclear units of 1 and 2 are assemb…
Hexanuclear NiII4LnIII2 Complexes with SMM Behavior at Zero Field for Ln = Tb, Dy, Ho
2020
A mononuclear Ni(II) complex, [NiL2]·2H2O, was prepared by the reaction of a N2O2 donor monocondensed Schiff base ligand, 2-((3-aminopropylimino)methyl)-6-methoxyphenol (HL), with NiCl2·6H2O. The reaction of this complex with NiCl2·6H2O and LnCl3·6H2O (Ln = Gd, Tb, Dy, Ho) in a 1:1:1 molar ratio leads to four hexanuclear Ni4Ln2 complexes formulated as [{(NiL)2Gd}2(μ2-Cl)2(μ3-OH)4(OH2)4]Cl4·CH3CN·H2O (1), [{(NiL)2Tb}2(μ2-Cl)2Cl2(μ3-OH)4(OH2)2]Cl2·12H2O (2), [{(NiL)2Dy}2(μ2-Cl)2Cl2(μ3-OH)4(OH2)2]Cl2·16H2O (3), and [{(NiL)2Ho}2(μ2-Cl)2(μ3-OH)4(OH2)4]Cl4·CH3CN·1.8H2O (4). The Ln(III) centers are octacoordinated with a triangular-dodecahedral geometry, and the geometries around the Ni(II) center…
Synthesis, X-ray crystal structure and magnetic study of a novel μ2-1,1-azido bridged dimeric copper(II) complex
2007
Abstract A new azido derivative of tridentate Schiff base copper(II) complex has been synthesized and characterized. X-ray single crystal structure analysis reveals that the complex [Cu2L2(N3)2(NO3)2] (1), containing 1-(N-pyridylimino)-3-aminopropane (L) as co-ligand, is a dimer in which copper(II) ions are bridged by two azido groups in end-on fashion. The coordination environment around copper(II) is distorted octahedral which is rarely observed among these types of azido bridged copper(II) dimers. Three among the four coordination sites of the basal plane of the octahedron are occupied by the nitrogen atoms of the Schiff base and the fourth site is occupied by a nitrogen atom of a μ2-1,1…
Mononuclear Mn(III) and dinuclear Mn(III,III) Schiff base complexes: Influence of π–π stacking on magnetic properties
2012
Abstract Synthesis of a mononuclear Mn(III) (1) and a dinuclear Mn(III, III) (2) complex of a tetradentate N2O2 donor Schiff base ligand with ancillary carboxylate ligands are reported. Complex 1 crystallizes in the monoclinic space group C2/c, complex 2 in the triclinic space group P-1. In both complexes the central Mn(III) ions are hexacoordinated having a distorted octahedral MnN2O4 coordination environment. Intermolecular hydrogen bonding and strong π–π stacking in both 1 and 2 leads to dimerization of 1 and formation of a syn–anti one-dimensional chain for 2. Magnetic properties of 1 and 2 are reported. Both complexes show very weak intermolecular antiferromagnetic interaction. Most in…
A study of the exchange interaction through phenolato, oximato and oxamidato bridges in MnIICuII dimers. Crystal structure of [Cu(salen)Mn(hfa)2]
1993
Abstract Three new heterodinuclear CuIIMnII complexes of formula [Cu(salen)Mn(hfa)2] (1), [Cu(pdmg)Mn(phen)2](ClO4)2·2.5H2O (2) and [Cu(apox)Mn(bpy)2](ClO4]2·0.5H2O (3) (salen=N,N′-ethylenebis(salicylideneiminate), hfa=hexafluoroacetylacetonate, pdmg=3,9-dimethyl-4,8-diazaundeca-3,8-diene-2,10-dione dioximate, phen=1,10- phenanthroline, apox=N,N′-bis(3-aminopropyl)oxamidate and bipy=2,2′-bipyridyl) have been synthesized. The crystal and molecular structure of 1 has been determined by X-ray diffraction methods. It crystallizes in the triclinic system, space group P 1 with cell constants a=15.584(4), b=12.039(3), c=9.470(2) A, α=113.83(2), β=107.17(3), γ=84.28(3)°; V=1552(1) A3, D (calc., Z=2…
Synthesis, structural aspects and magnetic properties of an unusual 2D thiocyanato-bridged cobalt(II)–Schiff base network
2010
Abstract A new two-dimensional (2D) thiocyanato-bridged cobalt(II) network formulated as [LCo2(NCS)2]n (1), has been synthesized with the Schiff base ligand N,N′-bis(3-methoxysalicylidenimino)-1,3-diaminopropane (H2L) and thiocyanate anions. This novel layered compound has been completely characterized by elemental analysis, FT-IR, UV–Vis spectroscopy and the structure has been established by single crystal X-ray diffraction studies. The structure of 1 consists of a doubly phenoxo-bridged dimer comprising two different cobalt(II) centers with different coordination geometries (octahedral and tetrahedral). The 2D network is accomplished by bridging thiocyanate ligands, connecting the dimeric…
Synthetic and natural chromium bearing spinels: an optical spectroscopy study
2014
Four samples of synthetic chromium-bearing spinels of (Mg, Fe2+)(Cr, Fe3+)2O4 composition and four samples of natural spinels of predominantly (Mg, Fe2+)(Al, Cr)2O4 composition were studied at ambient conditions by means of optical absorption spectroscopy. Synthetic end-member MgCr2O4 spinel was also studied at pressures up to ca. 10 GPa. In both synthetic and natural samples, chromium is present predominantly as octahedral Cr3+ seen in the spectra as two broad intense absorption bands in the visible range caused by the electronic spin-allowed 4A2g → 4T2g and 4A2g → 4T1g transitions (U- and Y-band, respectively). A distinct doublet structure of the Y-band in both synthetic and natural spine…
Water‐Soluble Heteronuclear [NaCu II 6 ] Metallomacrocyclic Sandwich Complexes: Synthesis, Structure, Properties and In Vitro Biological Studies
2014
The water-soluble heteronuclear metallomacrocyclic sandwich clusters [NaCu6(hpnbpda)3(OH)3(OH2)3](NO3)·4H2O (1), [NaCu6(hpnbpda)3(OH)3(OH2)3](ClO4) (2), and [NaCu6(hpnbpda)3(OH)3(OH2)3](PF6) (3) [H3hpnbpda = N,N′-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N′-diacetic acid] have been synthesized in methanol at room temperature and fully characterized using several analytical techniques including single-crystal X-ray diffraction. The molecular architecture of complex 1 is built from the template assembly of three dinuclear [Cu2(hpnbpda)]+ fragments through their weak oxophillic interactions with a central sodium(I) cation. A close analysis of the single-crystal X-ray structure reveal…
Raman spectroscopy of the high- and low-spin states of the spin crossover complex Fe(phen)2(NCS)2: an initial approach to estimation of vibrational c…
2000
Abstract Raman spectra of the spin-crossover complex Fe(phen)2(NCS)2 in the solid state have been recorded at 785 nm as a function of temperature to investigate the contribution of intramolecular vibrations to the entropy change, ΔS, associated with spin crossover. The modes of major interest for estimating the contribution lie in the range 100–500 cm−1, where the largest qualitative changes with temperature in the Raman spectra were observed. Analysis of these data, with the working assumption of an average frequency in this range as representative of the 15 distortion modes of an idealised FeN6 octahedron, leads to the conclusion that the intramolecular vibrations represent a primary cont…
Synthesis and spectroscopic studies (Mo¨ssbauer, IR and NMR) of [R2SnCl2bipym] (R = butyl or phenyl) and the crystal and molecular structure of [Ph2S…
1994
Abstract The complexes [R 2 SnCl 2 bipym] (R = phenyl or butyl, bipym = 2,2′,6,6′-bipyrimidine) were synthesized and studied in solution by 1 H- and 13 C-NMR spectroscopy and in the solid state by IR and Mo¨ssbauer spectroscopy. The latter was also performed in frozen ethanolic solution. The structure of the phenyl complex was determined by single crystal diffraction methods. The value obtained for the angle C-SN-C in the phenyl compound is 169.3(2)° (X-ray) and 151° (Mo¨ssbauer), but the assignment of an octahedral configuration by Mo¨ssbauer spectroscopy is consistent with the structure determined by diffraction. The butyl complex is also octahedral and the two techniques show better agre…