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Simon J Hibble

Publications and source records attributed to Simon J Hibble.

7 recordsLinked to original sources
PubMed2004

Bending, twisting, and breaking CuCN chains to produce framework materials: the reactions of CuCN with alkali-metal halides.

The reactions of the low-temperature polymorph of copper(I) cyanide (LT-CuCN) with concentrated aqueous alkali-metal halide solutions have been investigated. At room temperature, KX (X = Br and I) and CsX (X = Cl, Br, and I) produce the addition products K[Cu(2)(CN)(2)Br].H(2)O (I), K(3)[Cu(6)(CN)(6)I(3)].2H(2)O (II), Cs[Cu(3)(CN)(3)Cl] (III), Cs[Cu(3)(CN)(3)Br] (IV), and Cs(2)[Cu(4)(CN)(4)I(2)].H(2)O (V), with 3-D frameworks in which the -(CuCN)- chains present in CuCN persist. No reaction occurs, however, with NaX (X = Cl, Br, I) or KCl. The addition compounds, I-V, reconvert to CuCN when washed. Both low- and high-temperature polymorphs of CuCN (LT- and HT-CuCN) are produced, except in the case of Cs[Cu(3)(CN)(3)Cl] (III), which converts only to LT-CuCN. Heating similar AX-CuCN reaction mixtures under hydrothermal conditions at 453 K for 1 day produces single crystals of I-V suitable for structure determination. Under these more forcing conditions, reactions also occur with NaX (X = Cl, Br, I) and KCl. NaBr and KCl cause some conversion of LT-CuCN into HT-CuCN, while NaCl and NaI, respectively, react to form the mixed-valence Cu(I)/Cu(II) compounds [Cu(II)(OH(2))(4)][Cu(I)(4)(CN)(6)], a known phase, and [Cu(II)(OH(2))(4)][Cu(I)(4)(CN)(4)I(2)] (VI), a 3-D framework, which contains infinite -(CuCN)- chains. After 3 days of heating under hydrothermal conditions, the reaction between KI and CuCN produces [Cu(II)(OH(2))(4)][Cu(I)(2)(CN)I(2)](2) (VII), in which the CuCN chains are broken into single Cu-CN-Cu units, which in turn are linked into chains via iodine atoms and then into layers via long Cu-C and Cu-Cu interactions.

Journal Article↗
PubMed2004

Modeling the structure of amorphous MoS3: a neutron diffraction and reverse Monte Carlo study.

A model for the structure of amorphous molybdenum trisulfide, a-MoS3, has been created using reverse Monte Carlo methods. This model, which consists of chains of MoS6 units sharing three sulfurs with each of its two neighbors and forming alternate long, nonbonded, and short, bonded, Mo-Mo separations, is a good fit to the neutron diffraction data and is chemically and physically realistic. The paper identifies the limitations of previous models based on Mo3 triangular clusters in accounting for the available experimental data.

Journal Article↗
PubMed2003

Structure of AuCN determined from total neutron diffraction.

The structure of gold cyanide, AuCN, has been determined at 10 and 300 K using total neutron diffraction. The structure consists of infinite [bond]Au[bond](CN)[bond]Au[bond](CN)[bond] linear chains, hexagonally packed, with the gold atoms in sheets. The Au-C and Au-N bond lengths are found to be identical, with d(Au(-C/N) = 1.9703(5) A at 300 K. This work supersedes a previous study, by others, which used Rietveld analysis of neutron Bragg diffraction in isolation, and found these bonds to have significantly different lengths (Delta d = 0.24 A) at 300 K. The total correlation function, T(r), at 10 and 300 K, has been modeled using information derived from total diffraction. The broadening of inter- and intrachain correlations differs markedly due to random displacements of the chains in the direction of the chain axes. This is a consequence of the relatively weak bonding between the chains. An explanation for the negative thermal expansion in the c-direction, which occurs between 10 and 300 K, is presented.

Journal Article↗
PubMed2002

Beyond Bragg scattering: the structure of AgCN determined from total neutron diffraction.

Total neutron diffraction has yielded accurate bond lengths, Ag-C = Ag-N = 2.06 A and C-N = 1.16 A, for the disordered crystalline solid AgCN. This information cannot be obtained from analysis of Bragg scattering studies, because the (-Ag-CN-)(n) chains are randomly displaced along the chain axis relative to each other by a root-mean-square displacement of 0.24 A at 10 K. These results show the power of total neutron diffraction for determining structure in disordered systems.

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