On the Order-Disorder Phase Transformation of Anilinium Halides. III.

Fecher, Gerhard H.; Weiß, Alarich; Joswig, W.; Fueß, H.

doi:10.1515/zna-1981-0906

Cited by 19 publications

(3 citation statements)

References 13 publications

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“…The room tem perature data belong in all cases to the high tem perature phase I of the compounds. From the crystal structure determination of C6H5NH®Ie (phase I and phase II) [2][3][4] and from the crystal structures of 4-FC6H4N H l r (phase I and phase II) [10] we find, that in phase I of these compounds the group -NH® performs a hindered rotation, occu pying thereby two distinct positions in the lattice. From the 127I NQR study of all other compounds we conclude that a similar mechanism is valid for them in phase I too.…”

Section: -(Ch3)c6h4nd®316mentioning

confidence: 99%

“…In case of R=C6Hs a ferroelastic phase transition occurs for both the anilinium bromide and the anilinium iodide and this transition was followed up by 9 slBr and 12 I nuclear quadrupole resonance (NQR) [1]. The crystal structures of both the high and low temperature phases of C6H5N H 3X (X = Br, I) were studied by X-ray and neutron diffraction [2][3][4] by NQR [5], In detail we have studied the influence of a substituent at the para position of the anilinium ion. Phase transitions have been observed in 4-ClC6H4N H fle [6], and in 4-FC6H4N H ?X e , 4-(C2H5)C6H4N H ?X e (X = Br.…”

Section: Introductionmentioning

confidence: 99%

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Phase Transition in 4-(CH₃)C₆H₄NH^⊕ ₃X^⊖ (X = Br, I)

Bai

Weiß

1984

Zeitschrift Für Naturforschung A

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Bv 79-81 Br apd ,27I NQR spectroscopy 4-(CH3)C6H4NHf Xe , X = Br and I, and 4-(CH3)C6H4ND f 19 were studied in the temperature range' 77 S 7VK ^ 340. The three compounds experience phase transitions, most likely of higher order. Two reversible transitions are observed for the para-toluidinium iodide. 7~i-n being in the temperature range 247 ^ T/K ^ 258. Tn^m in the range 174 § 77K $ 179. The deuterated compound shows slight shift of the transition temperatures compared to the protonated one. whereas the l27I-NQR resonance frequencies are considerably lowered as is the nuclear quadrupole coupling constant. The asymmetry parameter tj, however, increases through deuteration of the NH3 group. The room temperature phase of the iodide crystallizes with an orthorhombic space group (Pmmn or Pmn2,.Z = 2). Temperature dependence of the 7vBrNQR spectrum of p-toluidinium bromide indicates a phase transition near t = 281 K. P h a s e T r a n s itio n in 4 -( C H 3) C 6H 4N H | X 9 (X = B r , I) Introduction © The ammonium ion. N H 4 , plays an important role in solid state phase transitions. It behaves like an alkali ion by its electronegativity and its radius, but due to its nonspherical symmetry and the ability to form hydrogen bonds, various packings and co ordinations are possible which promote phase transitions. Replacement of one hydrogen atom of the ion by a group R lowers the symmetry of the ion but the possibility of hydrogen bonding to the anions in the crystal lattice and the ease of rotation of the group -N H 3 around the bond R -NH 3 offers a variety of phases in the solid state which differ only little in lattice energy.In recent years we have studied several crystalline halides RNH?Xe (X = Br, CI) where R is the benzene ring or a substituted benzene ring. In case of R=C6Hs a ferroelastic phase transition occurs for both the anilinium bromide and the anilinium iodide and this transition was followed up by 9 slBr and 12 I nuclear quadrupole resonance (NQR) [1]. The crystal structures of both the high and low temperature phases of C6H5N H 3X (X = Br, I) were studied by X-ray and neutron diffraction In order to study the isotope effect, 4-(CH3)-C6H4N H 3I was dissolved in D20 and the solu tion was concentrated over P2Os in a dessicator.0340-4811 / 84 / 0400-380 S 01.3 0/0. -Please order a reprint rather than making your own copy.

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Section: -(Ch3)c6h4nd®316mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase Transition in 4-(CH₃)C₆H₄NH^⊕ ₃X^⊖ (X = Br, I)

Bai

Weiß

1984

Zeitschrift Für Naturforschung A

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“…In the foregoing paper [9] the crystal structure of the orthorhombic high temperature phase I of anilinium bromide is described, including the positional parameters of the hydrogen atoms and the disorder of the whole cation C6H5NH3®. There is a very recent determination of the monoclinic structure of the low temperature phase II by Sakai and Terauchi [10].…”

Section: Introductionmentioning

confidence: 99%