Experimental and computational study of HXeY•••HX complexes (X, Y=Cland Br):: An example of exceptionally large complexation effect

The complexes of xenon hydrides HXeY (Y = Cl and Br) with hydrogen halides HX (X = Cl and Br) have been studied both computationally and experimentally in a xenon matrix. The experiments revealed three new complexes: HXeBr center dot center dot center dot HBr, HXeBr center dot center dot center dot HCl, and HXeCl center dot center dot center dot HCl. The experimental assignments were done on the basis of the strong H-Xe stretching absorption of HXeY (Y = Cl and Br) molecules and supported by theoretical results. We experimentally obtained monomer-to-complex blue-shifts of this vibrational mode for all the studied systems (up to similar to 150 cm(-1)). The electronic structure calculations revealed three local structures for each HNgY center dot center dot center dot HX complexes and their computed interaction energies varied between -460 and -2800 cm(-1). The computational estimates of the vibrational shifts were in agreement with the experimental values. We also found possible experimental absorption belonging to HXeBr center dot center dot center dot(HBr)(2) trimer and its vibrational shift (+245 cm(-1)) is similar to the computational estimate of a cyclic ternary complex (+252 cm(-1)).