X-ray structure and crystal packing analysis of triphenylchloromethane

Abstract

IntroduetlonC19H15C1 is trigonal, space group P3, with a = 13.998 (2), c = 13.202 (4)/k, V = 2240.2 A 3, Z = 6, Dm= 1.26, D x = 1.240 Mg m -3, F(000) = 876,/~ = 0.225 mm-k The final R and R w, based on 905 reflections, are 0.038 and 0.025 respectively. The molecules lie in special positions on the crystallographic threefold axes. They are associated in pairs and form two distinct Ph3C-C1...CI-CPh 3 head-to-head arrangements characterized by long C-C1 bonds and short C1... CI contacts. The shortest C1... C1 distance (3.210 A) is about 0.3/k smaller than the sum of the van der Waals radii. For the sake of comparison, the lattice energy was computed using two different sets of Buckingham potential functions. The effects of including electrostatic terms were also investigated. These calculations account satisfactorily for all the salient features of the crystal packing. Analysis of the thermal motion showed that the rigid-body approximation holds reasonably well for the triphenylchloromethane molecule.

Chlorinated Derivatives of C78‐Fullerene Isomers with Unusually Short Intermolecular Halogen–Halogen Contacts

“…[17] To our knowledge, no other crystal structures of chlorinated hydrocarbons with such short Cl···Cl separations between chlorine atoms involved in highly elongated C À Cl bonds (above 1.85 ) have ever been reported. Recently, we have found that the chlorine atoms in the structure of C 76 Cl 18 form a number of extremely short Cl···Cl contacts of about 3.14-3.21 , [3] which are about 0.45 shorter than the sum of the van der Waals radii.…”

X-ray structure and crystal packing analysis of triphenylbromomethane, C19H15Br

“…Crystallographically equivalent TPBM and TPCM molecules have very similar overall geometries; in particular, the distortions from tetrahedral angular symmetry at the central Cc atom are equal within experimental error (average C-Cc-C and Ci-Cc-X angle values 112.3 and 106-5 °, respectively). The internal steric interactions already detailed for TPCM (Dunand & Gerdil, 1982) are equally operative in TPBM. The dihedral angles between the phenyl mean planes and the plane through the C-C-Br fragment are 51.1, 46.6 and 44.0 °, respectively.…”

“…The present study is a natural extension to our recent investigation of the crystal structure and crystal packing of triphenylchloromethane (Dunand & Gerdil, 1982). Triphenylchloromethane (TPCM) and triphenylbromomethane (TPBM) crystallize in isomorphous systems and both structures display linear head-to-head C-X.…”

Connectivity of the Chiral D2‐Symmetric Isomer of C76 through a Crystal‐Structure Determination of C76Cl18⋅TiCl4

“…Moreover, such short Cl···Cl contacts cannot be explained by the close packing of anisotropic building units. [14] We regard the short contacts as evidence of unconventional attractive interaction between the chlorine atoms.…”