Iodine and chlorine nuclear quadrupole coupling in the rotational spectra of Ar⋯ICl and ICl: intramolecular charge transfer induced in ICl by Ar

Accurate values of the ground-state spectroscopic constants B0, DJ, χaa(I), χaa(Cl) and Mbb(I) were determined for the two isotopomers Ar⋯I35Cl and Ar⋯I37Cl of a linear complex of argon and iodine monochloride from analyses of their rotational spectra. Interpretation of the changes in the nuclear quadrupole coupling constants χaa(I) and χaa(Cl) of Ar⋯ICl from those χ0(I) and χ0(Cl), respectively, of the free molecule shows that the electric charge redistribution within ICl when Ar⋯ICl is formed is equivalent to the transfer of 5.4×10−3 e from I to Cl. The intermolecular distance r(Ar⋯I) and stretching force constant kσ were determined to be 3.576 Å and 3.20 N m−1, respectively.