Molecular structure and ring distortions of p-dicyano-benzene in the gas phase and in the crystal

Marcello Colapietro, Aldo Domenicano, Gustavo Portalone, György Schultz, I. Hargittai

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

The molecular structure of p-dicyanobenzene has been accurately determined in the gas phase (by electron diffraction) and in the solid state (by X-ray crystallography). The benzene ring deviates significantly from D6h symmetry. The most appreciable distortion is an increase from 120° of the internal angle at the ipso carbon, α, as expected with a highly polar substituent. There appears to be a small difference in the values of α in the two phases. In the gas phase α is 122.1 ± 0.2°, while in the crystal it is 121.2(1)° [121.6(1)° when only high-θ reflexions are used in the refinement]. The gas versus crystal difference is consistent with an attenuation of the polar character of the substituent in the crystal, caused by intermolecular interactions that involve adjacent, antiparallel cyano groups. A less pronounced distortion of the benzene ring is a ca. 0.005 Å shortening of the central CC bonds, as compared with the CipsoCortho bonds. Other important bond distances from the electron diffraction study are: rg(CC)mean 1.397 ± 0.0003 Å, rg(CCN) 1.454 ± 0.005 Å, rg(CN) 0.002 Å. The corresponding figures from the X-ray diffraction study are 1.388(1), 1.441(1) and 1.145(2)Å, respectively. The differences with gas phase results arise in part from the different physical meaning of the bond length determined by the two techniques, and in part from thermal motions in the crystal. If these effects are accounted for, the aforementioned bond distances become 1.400(2), 1.445(2) and 1.169(2) Å, respectively, in agreement with gas phase results.

Original languageEnglish
Pages (from-to)141-157
Number of pages17
JournalJournal of Molecular Structure
Volume112
Issue number1-2
DOIs
Publication statusPublished - 1984

Fingerprint

Benzene
Molecular Structure
Molecular structure
molecular structure
Gases
benzene
vapor phases
Crystals
rings
crystals
electron diffraction
Electron diffraction
Electrons
crystallography
X ray crystallography
X Ray Crystallography
Bond length
x rays
X-Ray Diffraction
attenuation

ASJC Scopus subject areas

  • Structural Biology
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Materials Science (miscellaneous)
  • Atomic and Molecular Physics, and Optics

Cite this

Molecular structure and ring distortions of p-dicyano-benzene in the gas phase and in the crystal. / Colapietro, Marcello; Domenicano, Aldo; Portalone, Gustavo; Schultz, György; Hargittai, I.

In: Journal of Molecular Structure, Vol. 112, No. 1-2, 1984, p. 141-157.

Research output: Contribution to journalArticle

Colapietro, Marcello ; Domenicano, Aldo ; Portalone, Gustavo ; Schultz, György ; Hargittai, I. / Molecular structure and ring distortions of p-dicyano-benzene in the gas phase and in the crystal. In: Journal of Molecular Structure. 1984 ; Vol. 112, No. 1-2. pp. 141-157.
@article{b85649e78ba24631a7b870141a73575b,
title = "Molecular structure and ring distortions of p-dicyano-benzene in the gas phase and in the crystal",
abstract = "The molecular structure of p-dicyanobenzene has been accurately determined in the gas phase (by electron diffraction) and in the solid state (by X-ray crystallography). The benzene ring deviates significantly from D6h symmetry. The most appreciable distortion is an increase from 120° of the internal angle at the ipso carbon, α, as expected with a highly polar substituent. There appears to be a small difference in the values of α in the two phases. In the gas phase α is 122.1 ± 0.2°, while in the crystal it is 121.2(1)° [121.6(1)° when only high-θ reflexions are used in the refinement]. The gas versus crystal difference is consistent with an attenuation of the polar character of the substituent in the crystal, caused by intermolecular interactions that involve adjacent, antiparallel cyano groups. A less pronounced distortion of the benzene ring is a ca. 0.005 {\AA} shortening of the central CC bonds, as compared with the CipsoCortho bonds. Other important bond distances from the electron diffraction study are: rg(CC)mean 1.397 ± 0.0003 {\AA}, rg(CCN) 1.454 ± 0.005 {\AA}, rg(CN) 0.002 {\AA}. The corresponding figures from the X-ray diffraction study are 1.388(1), 1.441(1) and 1.145(2){\AA}, respectively. The differences with gas phase results arise in part from the different physical meaning of the bond length determined by the two techniques, and in part from thermal motions in the crystal. If these effects are accounted for, the aforementioned bond distances become 1.400(2), 1.445(2) and 1.169(2) {\AA}, respectively, in agreement with gas phase results.",
author = "Marcello Colapietro and Aldo Domenicano and Gustavo Portalone and Gy{\"o}rgy Schultz and I. Hargittai",
year = "1984",
doi = "10.1016/0022-2860(84)80251-3",
language = "English",
volume = "112",
pages = "141--157",
journal = "Journal of Molecular Structure",
issn = "0022-2860",
publisher = "Elsevier",
number = "1-2",

}

TY - JOUR

T1 - Molecular structure and ring distortions of p-dicyano-benzene in the gas phase and in the crystal

AU - Colapietro, Marcello

AU - Domenicano, Aldo

AU - Portalone, Gustavo

AU - Schultz, György

AU - Hargittai, I.

PY - 1984

Y1 - 1984

N2 - The molecular structure of p-dicyanobenzene has been accurately determined in the gas phase (by electron diffraction) and in the solid state (by X-ray crystallography). The benzene ring deviates significantly from D6h symmetry. The most appreciable distortion is an increase from 120° of the internal angle at the ipso carbon, α, as expected with a highly polar substituent. There appears to be a small difference in the values of α in the two phases. In the gas phase α is 122.1 ± 0.2°, while in the crystal it is 121.2(1)° [121.6(1)° when only high-θ reflexions are used in the refinement]. The gas versus crystal difference is consistent with an attenuation of the polar character of the substituent in the crystal, caused by intermolecular interactions that involve adjacent, antiparallel cyano groups. A less pronounced distortion of the benzene ring is a ca. 0.005 Å shortening of the central CC bonds, as compared with the CipsoCortho bonds. Other important bond distances from the electron diffraction study are: rg(CC)mean 1.397 ± 0.0003 Å, rg(CCN) 1.454 ± 0.005 Å, rg(CN) 0.002 Å. The corresponding figures from the X-ray diffraction study are 1.388(1), 1.441(1) and 1.145(2)Å, respectively. The differences with gas phase results arise in part from the different physical meaning of the bond length determined by the two techniques, and in part from thermal motions in the crystal. If these effects are accounted for, the aforementioned bond distances become 1.400(2), 1.445(2) and 1.169(2) Å, respectively, in agreement with gas phase results.

AB - The molecular structure of p-dicyanobenzene has been accurately determined in the gas phase (by electron diffraction) and in the solid state (by X-ray crystallography). The benzene ring deviates significantly from D6h symmetry. The most appreciable distortion is an increase from 120° of the internal angle at the ipso carbon, α, as expected with a highly polar substituent. There appears to be a small difference in the values of α in the two phases. In the gas phase α is 122.1 ± 0.2°, while in the crystal it is 121.2(1)° [121.6(1)° when only high-θ reflexions are used in the refinement]. The gas versus crystal difference is consistent with an attenuation of the polar character of the substituent in the crystal, caused by intermolecular interactions that involve adjacent, antiparallel cyano groups. A less pronounced distortion of the benzene ring is a ca. 0.005 Å shortening of the central CC bonds, as compared with the CipsoCortho bonds. Other important bond distances from the electron diffraction study are: rg(CC)mean 1.397 ± 0.0003 Å, rg(CCN) 1.454 ± 0.005 Å, rg(CN) 0.002 Å. The corresponding figures from the X-ray diffraction study are 1.388(1), 1.441(1) and 1.145(2)Å, respectively. The differences with gas phase results arise in part from the different physical meaning of the bond length determined by the two techniques, and in part from thermal motions in the crystal. If these effects are accounted for, the aforementioned bond distances become 1.400(2), 1.445(2) and 1.169(2) Å, respectively, in agreement with gas phase results.

UR - http://www.scopus.com/inward/record.url?scp=0001249195&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001249195&partnerID=8YFLogxK

U2 - 10.1016/0022-2860(84)80251-3

DO - 10.1016/0022-2860(84)80251-3

M3 - Article

AN - SCOPUS:0001249195

VL - 112

SP - 141

EP - 157

JO - Journal of Molecular Structure

JF - Journal of Molecular Structure

SN - 0022-2860

IS - 1-2

ER -