Electric charge redistribution in BrCl resulting from interaction with Ar:the rotational spectrum of the linear complex Ar center dot center dot center dot BrCl

Ground-state rotational spectra of four isotopomers Ar . . . (BrCl)-Br-79-C l-35, Ar . . . (BrCl)-Br-81-Cl-35, Ar . . . (BrCl)-Br-79-Cl-37 and Ar . . . (BrCl)-Br-81-Cl-37 of a complex involving argon and bromine monochloride w ere observed. Spectroscopic constants were interpreted on the basis of a li near species Ar . . . BrCl, with atoms in the indicated order and r(Ar . . . Br) = 3.466 Angstrom. When intermolecular electron transfer was assumed n egligible, the Br and Cl nuclear quadrupole coupling constants were interpr eted to show that a fraction delta (Br --> Cl) = 3.5(5) x 10(-3) of an elec tron is transferred from Br to Cl on complex formation. The values k(sigma) = 2.79(l) N m(-1) and k(beta beta) = 4.7(2) x 10(-20) J rad(-2) were estab lished for the intermolecular stretching and bending quadratic force consta nts, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.