Matrix-Isolation and Ab Initio Study of the HKrCl···HCl Complex

Abstract

The HKrCl complex with HCl is characterized by IR spectroscopy in a Kr matrix and by ab initio calculations. The HKrCl...HCl complex exhibits a strong blue shift of the H-Kr stretching mode in comparison with the HKrCl monomer, which indicates stabilization of the H-Kr bond upon complexation. The obtained maximal shift of ca. +300 cm(-1) is probably the largest blue shift experimentally observed for 1:1 molecular complexes. The HCl absorptions are found to be strongly red-shifted upon complexation with HKrCl (up to ca. -500 cm(-1)). In the HKrCl synthesis procedure, an HCl/Kr matrix was first photolyzed at 193 nm to yield H and Cl atoms in a Kr matrix and then annealed at about 30 K to activate mobility of H atoms and to promote the H + Kr + Cl reaction. The HKrCl...HCl complex is mainly formed from the Cl...HCl intermediate complex that is produced by photolysis of HCl dimers. Bands of the HKrCl...(HCl)(2) complex are tentatively identified with a very large shift of ca. +700 cm(-1) for the H-Kr stretching mode. These experimental observations are supported and explained by ab initio calculations.