Carbon tetrachloride–thiourea (1/3) adduct at 170 K

Fait, James F.; Fitzgerald, A.; Caughlan, Charles N.; McCandless, F. P.

doi:10.1107/s0108270190004577

Cited by 14 publications

(6 citation statements)

References 10 publications

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“…In these compounds the host lattice contains extensively Hbonded thiourea molecules, which form hexagonal, unidirectional, nonintersecting channels, which diameter ranges from 5.8 A to 7.1 A [1]. These channels can accommodate various organic guest molecules such as CCl 4 [2], cyclohexane and some of its derivatives, ferrocene and other organometallics, compounds containing benzene rings, long-branched hydrocarbons [3] or cycloheptane, cyclooctane and cyclooctanone [4]. Thiourea inclusion compounds usually crystallize in rhombohedral or monoclinic systems and in many cases the rhombohedral structure transforms to monoclinic form at low temperature [3].…”

Section: Introductionmentioning

confidence: 99%

Structure, phase transitions and dielectric properties of a new inclusion compound of bis-thiourea pyridinium nitrate salt

Małuszyńska¹,

Czarnecki²

2006

Zeitschrift Für Kristallographie - Crystalline Materials

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Inclusion compounds / Phase transitions / Bis-thiourea pyridinium nitrate salt / Single crystal structure analysis / X-ray diffraction Abstract. A structure of a new inclusion compound of bis-thiourea pyridinium nitrate salt C 5 H 6 N þ NO 3 À 2[CH 4 N 2 S] was determined by single-crystal X-ray diffraction method at 293 K, 250 K and 150 K. In high temperature phase the compound crystallizes in orthorhombic system, the two low-temperature phases are monoclinic. The sequence of phases is: Pbnm ) P2 1 /c ) P2 1 . In the orthorhombic form (I) the a axis is doubled in respect to the monoclinic forms and pyridinium and nitrate ions are partially disordered. Both low-temperature monoclinic phases (II) and (III) are ordered but twinned by pseudomerohedry. In all three phases the host lattice is built of ribbons of hydrogen-bonded thiourea molecules and nitrate anions forming channels in which the guests pyridinium cations are located. Each ribbon consists of two crystallographically independent thiourea molecules and nitrate ions. Four ribbons form a channel parallel to the c axis with approximately square cross-section. In the channel there is a stack of pyridinium cations, which planes form an inclination angle with the channel axis. The angle varies from about 90 in disordered phase I to 60 in well ordered phase (III).The dielectric spectroscopy measurements were performed on the polycrystalline sample with HP-4291A impedance analyser in the frequency range 1 MHz-1 GHz. The dielectric measurements reveal that two phase transitions occur at T 1 ¼ 287 K and at T 2 ¼ 217 K. The phase transition at T 2 ¼ 287 K is of the first order with the thermal hysteresis of 10 K at cooling and heating. The phase transition at 217 K is of the second order and the dielectric anomaly suggests the ferroelectric-paraelectric phase transition. The dielectric relaxation observed below T 2 are caused by the pyridinium cation reorientation. The dielectric relaxation time changes with the temperature according to Arrhenius low and the activation energy of the relaxation process is about 14 kJ/mol.

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Section: Introductionmentioning

confidence: 99%

Structure, phase transitions and dielectric properties of a new inclusion compound of bis-thiourea pyridinium nitrate salt

Małuszyńska¹,

Czarnecki²

2006

Zeitschrift Für Kristallographie - Crystalline Materials

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“…[4][5][6][7] Thiourea is known to form inclusion compounds with different organic molecules, e.g., cycoalkanes, branched hydrocarbons, cyclohexane, and substituted benzene rings. [7][8][9][10][11][12][13][14][15][16] But much less is known about thiourea with certain organic salts. These complexes are ionic-molecular systems held by van der Waals and Coulomb interactions as well as hydrogen bonds.…”

Section: Discovery Of An Intermediate Phase In Bis-thiourea Pyridiniumentioning

confidence: 99%

Discovery of an intermediate phase in bis-thiourea pyridinium chloride inclusion compound

Pajzderska

Wąsicki

Czarnecki

et al. 2009

The Journal of Chemical Physics

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This paper reports the occurrence of a new phase for bis-thiourea pyridinium chloride inclusion compound, which is intermediate to the high- and low-temperature ones already reported. The structure of the intermediate phase was determined by the x-ray diffraction and the following sequence of space groups was obtained: Cmcm-->(237 K)Cmc2(1)-->(206 K)Pbca. The triplication of the lattice a parameter in the intermediate phase was observed. Detailed investigations of its phase transitions were performed by differential scanning calorimetry, x-ray diffraction, and dielectric spectroscopy methods. The phase transition at T(1)=237 K is continuous while at T(2)=206 K is discontinuous. Both phase transitions have been classified as of order-disorder type. The high- and low-temperature phases are nonpolar in contrast to the intermediate phase, for which we could not found ferroelectric ordering.

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“…1,2 The host lattice of these adducts was first described by Hermann 3 and Lenne ´4 who found a structure made of hexagonal channels with an approximate diameter of 6.1 Å. These channels can accommodate small molecules such as CCl 4 , 5 chloroform, larger molecules such as the long-branched hydrocarbons, 6,7 cycloalkanes, 8-10 some substituted aromatic ring systems, 11,12 and even some organometallic compounds. [13][14][15] Thiourea inclusion compounds have attracted a great deal of interest for their structural similarities to the zeolite.…”

Section: Introductionmentioning

confidence: 99%

“…Thiourea is known from 1947 to form inclusion compounds with a variety of organic guest molecules. , The host lattice of these adducts was first described by Hermann and Lenné who found a structure made of hexagonal channels with an approximate diameter of 6.1 Å. These channels can accommodate small molecules such as CCl 4 , chloroform, larger molecules such as the long-branched hydrocarbons, , cycloalkanes, − some substituted aromatic ring systems, , and even some organometallic compounds. − …”

Section: Introductionmentioning

confidence: 99%

Investigations of the Phase Transitions in Thiourea Inclusion Compounds with Cycloheptane, Cyclooctane, and Cyclooctanone

Maris¹,

Henson²,

Heyes³

et al. 2001

Chem. Mater.

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Variable temperature single-crystal X-ray diffraction and solid-state NMR experiments have been performed on the thiourea cycloheptane (TC7), cyclooctane (TC8), and cyclooctanone (TCO8) inclusion compounds. Three different phases have been evidenced for TC7 and four for TC8, while only one phase change at high temperature has been found for TCO8. At room temperature, the cyclooctane and cycloheptane adducts exhibit the classical rhombohedral lattice (space group R3̄c). In these structures, the well-resolved host thiourea structure is composed of one-dimensional nonintersecting channels running along the c axis. The guest molecules, located in the center of the channels, are highly disordered as confirmed by the solid-state 13C NMR spectra. Lowering temperature leads to a monoclinic phase resulting from the distortion of the room-temperature lattice where the guest molecules still have some degrees of disorder. Refinement has been performed with a model involving two cycloalkane rings. For TC8, a supplementary phase with a doubling of the b axis is observed below 200 K, having two apparently ordered cyclooctane rings with the same conformation. The cyclooctanone adduct, TCO8, is already monoclinic at room temperature with an ordered guest molecule stabilized within the thiourea channels by a hydrogen bond. Upon heating, a phase change can be detected by solid-sate NMR and X-ray powder diffraction just before decomposition.

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Carbon tetrachloride–thiourea (1/3) adduct at 170 K

Cited by 14 publications

References 10 publications

Structure, phase transitions and dielectric properties of a new inclusion compound of bis-thiourea pyridinium nitrate salt

Structure, phase transitions and dielectric properties of a new inclusion compound of bis-thiourea pyridinium nitrate salt

Discovery of an intermediate phase in bis-thiourea pyridinium chloride inclusion compound

Investigations of the Phase Transitions in Thiourea Inclusion Compounds with Cycloheptane, Cyclooctane, and Cyclooctanone

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