Hydrated hexacyanometallate(III) salts of triaqua(18-crown-6)lanthanoid(III) and tetraaqua(18-crown-6)lanthanoid(III) cations containing nine- and ten-coordinate lanthanoids.
15 Oct 2007-Acta Crystallographica Section C-crystal Structure Communications (International Union of Crystallography)-Vol. 63, Iss: 10
TL;DR: In these compounds, there are two independent anions, both lying across inversion centres, and the lanthanoid centres exhibit nine-coordination; in the crystal structures, an extensive series of hydrogen bonds links the components into a three-dimensional framework.
Abstract: Tetraaqua(18-crown-6)cerium(III) hexacyanoferrate(III) dihydrate, [Ce(C12H24O6)(H2O)4][Fe(CN)6]·2H2O, and tetraaqua(18-crown-6)neodymium(III) hexacyanoferrate(III) dihydrate, [Nd(C12H24O6)(H2O)4][Fe(CN)6]·2H2O, are isomorphous and isostructural in the C2/c space group, where the cations, which contain ten-coordinate lanthanoid centres, lie across twofold rotation axes and the anions lie across inversion centres. In these compounds, an extensive series of O—H⋯O and O—H⋯N hydrogen bonds links the components into a continuous three-dimensional framework. Triaqua(18-crown-6)lanthanoid(III) hexacyanoferrate(III) dihydrate, [Ln(C12H24O6)(H2O)3][Fe(CN)6]·2H2O, where Ln = Sm, Eu, Gd or Tb, are all isomorphous and isostructural in the P\overline{1} space group, as are triaqua(18-crown-6)gadolinium(III) hexacyanochromate(III) dihydrate, [Gd(C12H24O6)(H2O)3][Cr(CN)6]·2H2O, and triaqua(18-crown-6)gadolinium(III) hexacyanocobaltate(III) dihydrate, [Gd(C12H24O6)(H2O)3][Co(CN)6]·2H2O. In these compounds, there are two independent anions, both lying across inversion centres, and the lanthanoid centres exhibit nine-coordination; in the crystal structures, an extensive series of hydrogen bonds links the components into a three-dimensional framework.
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TL;DR: This work realizes, for the first time, the photochromism and photomagnetism of 3d-4f hexacyanoferrates at room temperature (RT) in [Eu(III))(18C6)(H2O)3]Fe(III)(CN)6·2 H2O (18-crown-6) and opens a new avenue for RT photomagnetic polycyanometallate compounds.
Abstract: Polycyanometallate compounds with both photochromism and photomagnetism have appealing applications in optical switches and memories, but such optical behaviors were essentially restricted to the cryogenic temperature. We realized, for the first time, the photochromism and photomagnetism of 3d-4f hexacyanoferrates at room temperature (RT) in [Eu(III)(18C6)(H2O)3]Fe(III)(CN)6·2H2O (18C6 = 18-crown-6). Photoinduced electron transfer (PET) from crown to Fe(III) yields long-lived charge-separated species at RT in air in the solid state and also weakens the magnetic susceptibility significantly. The PET mechanism and changing trend of photomagnetism differ significantly from those reported for known 3d-4f hexacyanoferrates. This work not only develops a new type of inorganic-organic hybrid photochromic material but opens a new avenue for RT photomagnetic polycyanometallate compounds.
123 citations
TL;DR: The coordination of 18-crown-6 to Ce[N(SiMe3)Ph(F)]3 ( Ph(F) = pentafluorophenyl) results in a κ(2)-18-c Crown-6 complex, a unique coordination mode for an f-block cation.
21 citations
TL;DR: Analysis of the β electron density and electrostatic potentials indicates that the axial ligands (three water molecules) generate a relatively small repulsion, with the lanthanide electron density being the reason for the moderate magnetic anisotropy found in these systems.
Abstract: A family of lanthanide metal complexes with the general formula [Ln(H2O)3(18-crown-6)](ClO4)3 (Ln = TbIII, DyIII, ErIII, and YbIII) has been synthesized. Their magnetic properties have been characterized by direct- and alternating-current SQUID measurements and analyzed with the help of CASSCF-type calculations. The DyIII and YbIII compounds show slow relaxation of magnetization under an external magnetic field. Analysis of the dependence of the relaxation time with the temperature and external magnetic field reveals that the main contributions are the quantum tunneling and Raman relaxation terms, respectively. Analysis of the β electron density and electrostatic potentials indicates that the axial ligands (three water molecules) generate a relatively small repulsion, with the lanthanide electron density being the reason for the moderate magnetic anisotropy found in these systems.
18 citations
TL;DR: The current state of studies on binary complex compounds [M1La]x·[M2Ab]y (M1 and M2 are the central ions, L and A are ligands) is considered, notably: synthesis, composition, structures, magnetic properties, and thermal decomposition.
Abstract: The current state of studies on binary complex compounds [M1La]x·[M2Ab]y (M1 and M2 are the central ions, L and A are ligands) is considered, notably: synthesis, composition, structures, magnetic properties, and thermal decomposition.
12 citations
TL;DR: The vibrational spectra obtained from the QMCF-MD simulations are in excellent agreement with experimental data and show a pronounced blueshift upon complexation of the strontium(II) ion in 18C6.
Abstract: Ab initio QMCF-MD simulations of aqueous 18-crown-6 (18C6) and strontium(II)-18-crown-6 (18C6–Sr) were performed to gather insight into their hydration properties. Strongly different characteristics were found for the two solutes in terms of structure and dynamics such as H-bonding. They, however, have in common that their backbone shows high flexibility in aqueous medium, adopting structures significantly differing from idealized gas phase geometries. In particular, planar oxyethylene units stable in the picosecond range occurred in 18C6, while the strontium complex readily exhibits a bent structure. Detailed analysis of this high flexibility was done via two dimensional root mean square deviation plots as well as the evolution of dihedral angles and angles within the simulation trajectory. The vibrational spectra obtained from the QMCF-MD simulations are in excellent agreement with experimental data and show a pronounced blueshift upon complexation of the strontium(II) ion in 18C6.
8 citations
References
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TL;DR: In this article, a review of the most promising systematic approaches to resolving this enigma was initially developed by the late M. C. Etter, who applied graph theory to recognize, and then utilize, patterns of hydrogen bonding for the understanding and design of molecular crystals.
Abstract: Whereas much of organic chemistry has classically dealt with the preparation and study of the properties of individual molecules, an increasingly significant portion of the activity in chemical research involves understanding and utilizing the nature of the interactions between molecules. Two representative areas of this evolution are supramolecular chemistry and molecular recognition. The interactions between molecules are governed by intermolecular forces whose energetic and geometric properties are much less well understood than those of classical chemical bonds between atoms. Among the strongest of these interactions, however, are hydrogen bonds, whose directional properties are better understood on the local level (that is, for a single hydrogen bond) than many other types of non-bonded interactions. Nevertheless, the means by which to characterize, understand, and predict the consequences of many hydrogen bonds among molecules, and the resulting formation of molecular aggregates (on the microscopic scale) or crystals (on the macroscopic scale) has remained largely enigmatic. One of the most promising systematic approaches to resolving this enigma was initially developed by the late M. C. Etter, who applied graph theory to recognize, and then utilize, patterns of hydrogen bonding for the understanding and design of molecular crystals. In working with Etter's original ideas the power and potential utility of this approach on one hand, and on the other, the need to develop and extend the initial Etter formalism was generally recognized. It with that latter purpose that we originally undertook the present review.
7,616 citations
TL;DR: Structural studies of these two families show that they are isomorphous, and the relationship in conjunction with the diamagnetism of the Co3+ allows an approximation to the nature of coupling between the iron( III) and the lanthanide(III) ions in the [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2 O complexes.
Abstract: The reaction of Ln(NO3)3.aq with K3[Fe(CN)6] or K3[Co(CN)6] in N,N'-dimethylformamide (DMF) led to 25 heterodinuclear [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2O and [Ln(DMF)4(H2O)3(mu-CN)Co(CN)5].nH2O complexes (with Ln = all the lanthanide(III) ions, except promethium and lutetium). Five complexes (Pr(3+)-Fe3+), (Tm(3+)-Fe3+), (Ce(3+)-Co3+), (Sm(3+)-Co3+), and (Yb(3+)-Co3+) have been structurally characterized; they crystallize in the equivalent monoclinic space groups P21/c or P21/n. Structural studies of these two families show that they are isomorphous. This relationship in conjunction with the diamagnetism of the Co3+ allows an approximation to the nature of coupling between the iron(III) and the lanthanide(III) ions in the [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2O complexes. The Ln(3+)-Fe3+ interaction is antiferromagnetic for Ln = Ce, Nd, Gd, and Dy and ferromagnetic for Ln = Tb, Ho, and Tm. For Ln = Pr, Eu, Er, Sm, and Yb, there is no sign of any significant interaction. The isotropic nature of Gd3+ helps to evaluate the value of the exchange interaction.
181 citations
TL;DR: The structure of the title compound has been determined from single-crystal X-ray analysis as mentioned in this paper, which is formed by [GdCl2EtOH(18-crown-6)]+ cations and Cl− anions.
25 citations