Synthesis, crystal structure, magnetic behavior and thermal property of three polynuclear complexes : [M(dca)2(H2O)2]n · (hmt)n [M = Mn(II), Co(II)] and [Co(dca)2(bpds)]n [dca, dicyanamide; hmt, hexamethylenetetramine; bpds, 4,4'-bipyridyl disulfide]
TL;DR: In this paper, three μ1,5-dicyanamide bridged Mn(II) and Co(II)-complexes have been synthesized and characterized by single crystal X-ray diffraction study, low temperature (300-2,K) magnetic measurement and thermal behavior.
About: This article is published in Inorganica Chimica Acta.The article was published on 2006-03-20. It has received 44 citations till now. The article focuses on the topics: Dicyanamide.
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TL;DR: In this paper, the main structural and topological types of coordination polymers bearing hexamethylenetetramine (hmt) are summarized, showing that a diversity of metal-organic networks can be generated by facile self-assembly routes in aqueous medium and using rather simple chemicals.
153 citations
TL;DR: In this article, the influence of the positional isomeric ligands on the structures and magnetic properties of their complexes was systematically investigated, and it was shown that the phenyl dicarboxylate anions display versatile coordination modes to manage the Co(II) ions to f...
Abstract: To systematically investigate the influence of the positional isomeric ligands on the structures and magnetic properties of their complexes, we synthesized ten Co(II) complexes with three positional isomeric dipyridyl ligands (4,4′-bpt, 3,4′-bpt and 3,3′-bpt), as well as the phenyl dicarboxylate anions, namely, [Co(o-BDC)(4,4′-bpt)(H2O)] (1), [Co(o-BDC)(3,3′-bpt)(H2O)] (2), [Co(3-Cl-o-BDC)(4,4′-bpt)(H2O)] (3), [Co(3-Cl-o-BDC)(3,4′-bpt)] (4), [Co(m-BDC)(3,4′-bpt)] (5), [Co(m-BDC)(3,3′-bpt)]·H2O (6), [Co2(5-NO2-m-BDC)2(3,4′-bpt)(H2O)4] (7), [Co(5-NO2-m-BDC)(3,3′-bpt)]·H2O (8), [Co(p-BDC)(3,4′-bpt)2(H2O)2]·2H2O (9), and [Co(p-BDC)(3,3′-bpt)2(H2O)2]·2H2O (10) (o-BDC = 1,2-benzenedicarboxylate anion, 3-Cl-o-BDC = 3-Cl-1,2-benzenedicarboxylate anion, m-BDC = 1,3-benzenedicarboxylate anion, 5-NO2-m-BDC = 5-NO2-1,3-benzenedicarboxylate anion, p-BDC = 1,4-benzenedicarboxylate anion). Structural analysis reveals that the phenyl dicarboxylate anions display versatile coordination modes to manage the Co(II) ions to f...
108 citations
TL;DR: In this paper , a composite aerogel (CoFe0.8@NCNT@CA) loaded with bimetallic MOF-derived carbon nanotubes was developed for activating peroxymonosulfate (PMS) to degrade tetracycline (TC).
60 citations
TL;DR: Analysis of the two-step spin-crossover character in this compound suggests that covalent interactions through the spacer ligand do not provide the main mechanism of cooperativity.
Abstract: We report here on the synthesis and characterisation of a first iron(II) spin-crossover coordination polymer with the dca spacer ligand, having the formula [Fe(aqin)2(dca)]ClO4⋅MeOH (aqin=8-aminoquinoline, dca=dicyanamide), which displays a two-step complete spin transition. Variable-temperature magnetic susceptibility measurements and Mossbauer spectroscopy have revealed that the two relatively gradual steps are centred at 215 and 186 K and are separated by an inflection point at about 201 K, at which 50 % of the complex molecules undergo a spin transition. The two steps are related to the existence of two crystallographically inequivalent metal sites, as confirmed by the structural and Mossbauer studies. The crystal structure was resolved at 293 K (HS form) and 130 K (LS form). Both spin-state structures belong to the triclinic P space group (Z=2). The complex assumes a linear chain structure, in which the active iron(II) sites are linked to each other by anionic dicyanamide ligands acting as chemical bridges. The Fe–Fe distances through the dca ligand are 8.119(1) and 7.835(1) A in the high-spin and low-spin structures, respectively. The polymeric chains extend along a (1, 0, −1) axis and are packed in sheets, between which the perchlorate anions and methanol molecules are inserted. The complex molecules are linked together by π-stacking interactions and H-bonding between the H-donor aqin ligands and the perchlorate ions. These structural features provide a basis for cooperative interactions in the crystal lattice. Analysis of the two-step spin-crossover character in this compound suggests that covalent interactions through the spacer ligand do not provide the main mechanism of cooperativity.
57 citations
TL;DR: In this paper, a new polymeric materials [M(dcno)2(H2O)2] [M = FeII (1), CoII (2), MnII (4) with dcno− =[(NC)2CC(O)O(CH2)2OH]− = 2,2-dicyano-1-(2-hydroxyethoxy)ethenolate anion have been synthesised and characterised by IR spectroscopy, X-ray crystallography and magnetic measurements.
Abstract: New polymeric materials [M(dcno)2(H2O)2] [M = FeII (1), CoII (2)] and [M(dcno)2] [M = CuII (3), MnII (4)] with dcno– =[(NC)2CC(O)O(CH2)2OH]– = 2,2-dicyano-1-(2-hydroxyethoxy)ethenolate anion have been synthesised and characterised by IR spectroscopy, X-ray crystallography and magnetic measurements. In compounds 1 and 2, each organic ligand acts in a bridging mode with its two nitrogen atoms bound to two different metal ions, while in compounds 3 and 4, each organic anion acts as a μ3-bridging ligand through its two nitrogen atoms and the oxygen atom of the OH group. Each metal ion has a pseudo-octahedral trans-MN4O2 environment with four nitrogen atoms from four different organic ligands and two oxygen atoms from two water molecules in compounds 1 and 2 and from the OH group of the cyanocarbanion ligand in compounds 3 and 4. These coordination modes give rise to 1D, 2D and 3D arrangements for compounds 1, 2 and 3–4, respectively. Magnetic measurements show weak antiferromagnetic coupling between metal centres in the four compounds.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
42 citations
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TL;DR: The methods presented in the chapter have been applied to solve a large variety of problems, from inorganic molecules with 5 A unit cell to rotavirus of 700 A diameters crystallized in 700 × 1000 × 1400 A cell.
Abstract: Publisher Summary X-ray data can be collected with zero-, one-, and two-dimensional detectors, zero-dimensional (single counter) being the simplest and two-dimensional the most efficient in terms of measuring diffracted X-rays in all directions. To analyze the single-crystal diffraction data collected with these detectors, several computer programs have been developed. Two-dimensional detectors and related software are now predominantly used to measure and integrate diffraction from single crystals of biological macromolecules. Macromolecular crystallography is an iterative process. To monitor the progress, the HKL package provides two tools: (1) statistics, both weighted (χ2) and unweighted (R-merge), where the Bayesian reasoning and multicomponent error model helps obtain proper error estimates and (2) visualization of the process, which helps an operator to confirm that the process of data reduction, including the resulting statistics, is correct and allows the evaluation of the problems for which there are no good statistical criteria. Visualization also provides confidence that the point of diminishing returns in data collection and reduction has been reached. At that point, the effort should be directed to solving the structure. The methods presented in the chapter have been applied to solve a large variety of problems, from inorganic molecules with 5 A unit cell to rotavirus of 700 A diameters crystallized in 700 × 1000 × 1400 A cell.
31,667 citations
TL;DR: The category Computer Program Abstracts provides a rapid means of communicating up-to-date information concerning both new programs or systems and signi®cant updates to existing ones.
Abstract: The category Computer Program Abstracts provides a rapid means of communicating up-to-date information concerning both new programs or systems and signi®cant updates to existing ones. Following normal submission, a Computer Program Abstract will be reviewed by one or two members of the IUCr Commission on Crystallographic Computing. It should not exceed 500 words in length and should follow the standard format given on page 189 of the June 1985 issue of the Journal [J. Appl. Cryst. (1985). 18, 189± 190] and on the World Wide Web at http://www.iucr. org/journals/jac/software/. Lists of software presented and/or reviewed in the Journal of Applied Crystallography are available on the World Wide Web at the above address, together with information about the availability of the software where this is known.
18,151 citations
TL;DR: In this paper, a Fortran program is developed for the reduction of single-crystal diffraction data from a sequence of adjacent rotation pictures recorded at a fixed X-ray wavelength by an electronic area detector.
Abstract: A Fortran program has been developed for the reduction of single-crystal diffraction data from a sequence of adjacent rotation pictures recorded at a fixed X-ray wavelength by an electronic area detector. The electronic pictures (data frames) covering the first 5° of crystal rotation are used to locate strong diffraction spots and to estimate the background. The orientation of the crystal is derived automatically from the list of observed spots and all parameters describing the diffraction pattern are refined. The only input required from the user is the specification of the space group, approximate cell dimensions and detector setting. When the initialization step is finished the program goes back to the first picture and evaluates all data frames in the order they arrive from the measurement. Each element of an electronic picture (pixel) is labelled by the indices of the nearest reflection using the current refined parameters describing the diffraction geometry. If the pixels close to its nearest reflection the counts contribute to the three-dimensional profile; otherwise the counts are used to update the background. Each profile is represented as if the reflection had followed the shortest path through the Ewald sphere and had been recorded on the surface of the sphere. Reflections close to the Ewald sphere are kept in a hash table to allow rapid access for updating the profiles. Reflections which have completely passed through the Ewald sphere are removed from the table and saved for further processing. Intensities are estimated by fitting their profiles to an average shape learned from strong neighbouring reflections. Smoothly varying scaling factors are applied to the Lp-corrected intensities which minimize discrepancies between symmetry-related reflections and fit to a reference data set if available.
1,519 citations
TL;DR: In this paper, it was shown that the free energy, susceptibility, and correlation functions for a linear chain of N spins with nearest-neighbor isotropic Heisenberg coupling can be calculated explicitly in the (classical) limit of infinite spin.
Abstract: It is observed that the free-energy, susceptibility, and correlation functions for a linear chain of N spins with nearest-neighbor isotropic Heisenberg coupling can be calculated explicitly in the (classical) limit of infinite spin. The results are compared briefly with those for Ising and Heisenberg chains of spin 12.
1,252 citations
TL;DR: In this paper, a review of the physical measurements made on the α-M(dca)2 series is given, together with interpretations for the different net exchange coupling and consequent 3D order.
959 citations