Journal of the Chemical Society, Faraday Transactions
Journal of the Chemical Society, Faraday Transactions; was published from 1990 - 1998. In 1999 it merged with a number of European chemical society physical Chemistry journals to become Physical Chemistry Chemical Physics.
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J. Chem. Soc., Faraday Trans., 1995, 91, 1891 - 1900, DOI: 10.1039/FT9959101891
The b
.a
complex C2H2
Cl2 characterised by rotational spectroscopy as an intermediate in a reactive mixture of ethyne and chlorineH. I. Bloemink, S. A. Cooke, K. Hinds, A. C. Legon and J. C. Thorn
An intermediate C2H2
Cl2 belonging to the b
.a
class of complex defined by Mulliken has been isolated in a reactive mixture of ethyne and molecular chlorine and characterised by means of its ground-state rotational spectrum, as observed with a fast-mixing nozzle incorporated in a pulsed-nozzle, Fourier-transform microwave spectrometer. Rotational constants A0, B0 and C0, quartic centrifugal distortion constants 
J, JK and 
J, and Cl-nuclear quadrupole coupling constants 
aa(Clx) and bb(Clx)–cc(Clx)(where x= i for inner or o for outer) were determined for the four isotopomers C2H235Cl2, C2H237Cl35Cl, C2H235Cl37Cl and C2D235Cl2. Detailed analyses of the spectroscopic constants established unambiguously that the observed complex has a planar, T-shaped geometry of C2v symmetry with Cl2 as the stem of the T, that the extent of electric charge redistribution within Cl2 on formation of the complex is equivalent to a transfer of only 0.02e from Cli to Clo, and that the binding strength, as measured by the intermolecular stretching force constant k
, is very small. The systematic shortening of the BCl distance from BHCl to BCl2 identified previously was also observed for B = C2H2 and has been attributed to the 
snub-nosed
nature of molecular chlorine.
