On a possible substitution of p-xylene by toluene in p-xylene crystals. The crystal structure of p-xylene, C₈H₁₀, at 180 K

Abstract

Mr=106.17, monoclinic, P21/n, a=5.806(2), b=

Neutron powder and ab initio structure of ortho-xylene: the influence of crystal packing on phenyl ring geometry at 2 K

“…Though the three isomers of xylene are familiar laboratory compounds, until recently little was known about their structure in the solid state. 2,4,5 We now describe the crystal structure of oxylene at low temperature which, in contrast to the other isomers, exhibits a strained ring conformation which we suggest may be attributed to weak intermolecular forces.A 2 g powder sample of perdeuterated o-xylene was prepared by the method described in ref. 6 and neutron powder diffraction data ‡ were collected at 2 K on the High Resolution Powder Diffractometer, HRPD, at the ISIS pulsed-neutron source, UK.…”

Hydrocarbon C—H Bond Activation with Tp'Pt Complexes

“…The average C-C bond lengths of the coordinated benzene (1.36 Â) are comparable to those of free benzene (1.39 Â) (85); in the p-xylene adduct the average C-C bond lengths (1.45 Â) are slightly longer than that for free p-xylene (1.39 Â) (86). The orientation of the arene plane relative to the square-plane of the metal is almost perdendicular in both complexes (17: 85.0 e and 19: 77.9°).…”

Thermodynamic properties of the methylpyridines. Part 1. Heat capacity measurements for 4-methylpyridine betweenT= 6.4 K andT= 18.6 K, resolution of low-temperature contributions, and reconciliation of calorimetrically and spectroscopically derived standard entropies

“…The structure was estimated with bond lengths listed by Draeger (22) for the pyridine ring. The C-H bond distances within the methyl group were assumed equal to those for methane, as reported by Bartell et al (23) The aromatic-carbon to methyl-carbon distance was estimated from a crystal structure of p-xylene reported by Koningsveld et al (24) The method of Lewis et al (25) was used to calculate the rotational energy levels using equation (2), and standard methods of statistical mechanics were used to calculate the heat capacity arising from their thermal population. The size of the three-fold rotation barrier V 3 was determined with the results of inelastic neutron scattering studies by Abed et al (2) and Alefeld et al (8) Alefeld et al (8) determined the splitting (4.19 ± 0.08) cm −1 between the ground and first excited state for the energy levels associated with rotation of the methyl group in 4-methylpyridine.…”