Disorder in crystalline tetraiodoethylene; constrained refinements of neutron powder diffraction data

Pawley, G. S.

doi:10.1107/s0567740878003477

Cited by 10 publications

(4 citation statements)

References 5 publications

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“…The unique carbon atom of one of the TIE molecules in 4Ph 3 PSe·TIE was disordered over two positions (70/30 distribution), and both carbon atoms were modeled with isotropic displacement parameters. This is a similar disorder to that observed in the crystal structure of TIE and is a consequence of the nearly square shape of the molecule (intramolecular I···I distances of 3.5 × 3.6 Å) . A cavity centered about the inversion center at (0.5, 0.0, 0.5) was partially occupied by an additional but uncomplexed TIE molecule.…”

Section: X-ray Diffraction Analysissupporting

confidence: 71%

Complementary Selenium···Iodine Halogen Bonding and Phenyl Embraces: Cocrystals of Triphenylphosphine Selenide with Organoiodides

Arman

Rafferty

Bayse

et al. 2012

Crystal Growth & Design

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Se···I Halogen bonding (XB) between triphenylphosphine selenide and organoiodides: 1,2-diiodotetrafluorobenzene (1,2-F4DIB), 1,4-diiodotetrafluorobenzene (1,4-F4DIB), and tetraiodoethylene (TIE) has been used to assemble molecules into finite adducts, chains, and two-dimensional layers. Phenyl embraces involving the triphenylphosphine groups extend these moieties into additional dimensions, leading in two cases (1,4-F4DIB and TIE) to open structures, with filled or partially filled cavities. Comparison of structural parameters for 26 reported zigzag chains of embracing Ph3XY reveals that this synthon can adapt its registry to accommodate widely diverse structures. The strengths of the XB interactions were analyzed using natural bond orbital (NBO) theory, which provides an estimate of the energy of a donor–acceptor interaction (ΔE d→a) through localization of the molecular orbitals. Structures of 1:1 and 1:2 XB complexes of Ph3PSe with 1,2-F4DIB and 1,4-F4DIB were optimized at the DFT(B97-1)/BSI level. The bond distance and angles obtained are in reasonably good agreement with the experimentally observed structures.

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Section: X-ray Diffraction Analysissupporting

confidence: 71%

Complementary Selenium···Iodine Halogen Bonding and Phenyl Embraces: Cocrystals of Triphenylphosphine Selenide with Organoiodides

Arman

Rafferty

Bayse

et al. 2012

Crystal Growth & Design

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“…This test, however, requires the number of degrees of freedom, a quantity which cannot be found at present for powder data. Here we follow Pawley (1978) in assuming that the number of observations, n, is given by the number of scan points divided by the average number of scan points in a peak, giving n = 900/26 = 34. Hamilton (1965) shows that is distributed as…”

Section: Room-temperature Structurementioning

confidence: 99%

“…It was suggested by Pawley (1978) that the effective number of observations, n, should be used in the calculation of the standard deviations instead of using the total number of reflections contributing to the scan. In the room-temperature scan the number of contributing reflections is 161, while n is about 34.…”

Section: Standard Deviationsmentioning

confidence: 99%

The structure of deuterated tetramethylammonium hexachloroplatinate investigated by neutron powder diffraction

Mackenzie¹,

Berg²,

Pawley³

1980

Acta Crystallogr Sect B

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Neutron powder diffraction patterns of [N(CD3)4] 2- [PtC16] have been measured at room temperature and 90 K and the data have been analysed using the constrained-refinement program EDINP. The roomtemperature pattern is consistent with an Fd3c structure with a unit-cell parameter doubled with respect to that found in earlier single-crystal studies in which the space group was assumed to be Fm3m. An improvement in the quality of the fit was obtained when one of the two tetramethylammonium ions in the asymmetric unit was allowed to be disordered over two orientations. The significance of this result is discussed and is thought to be high. The low-temperature structure has not yet been fully determined but the relative weakness of the superlattice reflections indicates that the distortion from Fm3m symmetry may be less than at room temperature.

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“…electrons on the nitrogen and oxygen acceptor sites appear to strengthen the electrostatic attraction compared with the belt of negative potential on iodine acceptor sites. However, the I···I networks of TIE do appear to be influential in directing the packing nature of these cocrystals, even if the three-dimensional I···I framework of TIE itself is never expressly duplicated in these structures. ,− The lattice parameters of TIE ( P 2 1 / c polymorph at room temperature, a = 15.076(2), b = 4.3845(7), c = 12.908(1)) are thematic to a certain degree in the cocrystals of 1B , 3B , 4B , 5B , 2′B , and 5′B where TIE···TIE interactions occur in conjunction with two crystallographic axes of ∼4.0–4.7 Å and ∼12.5–14.0 Å.…”

Section: Resultsmentioning

confidence: 99%

Comparison of N···I and N···O Halogen Bonds in Organoiodine Cocrystals of Heterocyclic Aromatic Diazine Mono-N-oxides

Padgett,

Dean,

Cobb

et al. 2024

Crystal Growth & Design

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A series of cocrystals of halogen bond donors 1,4-diiodotetrafluorobenzene (p-F4DIB) and tetraiodoethylene (TIE) with five aromatic heterocyclic diazine mono-N-oxides based on pyrazine, tetramethylpyrazine, quinoxaline, phenazine, and pyrimidine as halogen bonding acceptors were studied. Structural analysis of the mono-N-oxides allows comparison of the competitive occurrence of N···I vs O···I interactions and the relative strength and directionality of these two types of interactions. Of the aromatic heterocyclic diazine mono-N-oxide organoiodine cocrystals examined, six exhibited 1:1 stoichiometry, forming chains that utilized both N···I and O···I interactions. Two cocrystals presented 1:1 stoichiometry with exclusive O···I interactions. Two cocrystals displayed a 2:1 stoichiometryone characterized solely by O···I interactions and the other solely by N···I interactions. We have also compared these interactions to those present in the corresponding diazines, some of which we report here and some which have been previously reported. In addition, a computational analysis using density functional theory (M062X/def2-SVPD) was performed on these two systems and has been compared to the experimental results. The calculated complex formation energies were, on average, 4.7 kJ/mol lower for the I···O halogen bonding interaction as compared to the corresponding N···I interaction. The average I···O interaction distances were calculated to be 0.15 Å shorter than the corresponding I···N interactions.

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Disorder in crystalline tetraiodoethylene; constrained refinements of neutron powder diffraction data

Cited by 10 publications

References 5 publications

Complementary Selenium···Iodine Halogen Bonding and Phenyl Embraces: Cocrystals of Triphenylphosphine Selenide with Organoiodides

Complementary Selenium···Iodine Halogen Bonding and Phenyl Embraces: Cocrystals of Triphenylphosphine Selenide with Organoiodides

The structure of deuterated tetramethylammonium hexachloroplatinate investigated by neutron powder diffraction

Comparison of N···I and N···O Halogen Bonds in Organoiodine Cocrystals of Heterocyclic Aromatic Diazine Mono-N-oxides

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