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Characterisation of the Intermediate C 2 H 4 …︁Cl 2 in a Gaseous Mixture of Ethene and Chlorine by Rotational Spectroscopy: A Weak π‐Type Complex
Author(s) -
Bloemink Hannelore I.,
Hinds Kelvin,
Legon Anthony C.,
Thorn Joanna C.
Publication year - 1995
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19950010107
Subject(s) - chemistry , isotopomers , quadrupole , rotational spectroscopy , crystallography , isotopes of chlorine , coupling constant , spectroscopy , spectral line , analytical chemistry (journal) , atomic physics , chlorine , molecule , physics , organic chemistry , particle physics , quantum mechanics , astronomy , chromatography
A complex of ethene and Cl 2 has been characterised in the gas phase. Rotational spectra of the isotopomers C 2 H 4 … 35 Cl 2 , C 2 H 4 … 35 Cl 37 Cl and C 2 H 4 … 37 Cl 35 Cl were recorded by using a fast‐mixing nozzle in an FT microwave spectrometer. Rotational constants, centrifugal distortion constants and Cl nuclear quadrupole coupling constants. χ gg (Cl) are reported in each case. The complex is of the π‐donor–acceptor type and has a C 2 v geometry in which Cl 2 lies along the C 2 axis perpendicular to the plane of the C 2 H 4 nuclei. The binding is weak, and only small changes in the χ gg (Cl) attend complex formation. A simple model attributes these changes to a transfer of around 0.02 e from the inner to the outer Cl nucleus, thus confirming that the complex is of the Mulliken outer type. Similarities in the properties of C 2 H 4 … Cl 2 and C 2 H 4 … HCl indicate that the angular geometry is in both cases determined mainly by the electrostatic part of the interaction. The distance from the π‐bond midpoint to Cl decreases from C 2 H 4 … HCl to C 2 H 4 … Cl 2 ; this suggests that Cl 2 is “snub‐nosed”.