COVALENT AND NONCOVALENT INTERACTIONS BETWEEN BORON AND ARGON: AN INFRARED PHOTODISSOCIATION SPECTROSCOPIC STUDY OF ARGON-BORON OXIDE CATION COMPLEXES

Although a wide range of compounds of the heavy rare-gas elements are experimentally known, very few chemically bound molecules have been experimentally observed for the lighter noble gases. Here we report a combined infrared photodissociation spectroscopic and theoretical study on a series of argon-boron oxide cation complexes prepared via a laser vaporization supersonic ion source in the gas phase. Infrared spectroscopic combined with state-of-the-art quantum chemical calculations indicate that the chem{[ArB_3O_{4,5}]^+}, chem{[ArB_4O_{5-7}]^+} and chem{[ArB_5O_7]^+} cation complexes have planar structures each involving an aromatic boroxol ring and an argon-boron covalent bond formed between the in-plane 2p atomic orbitals of Ar and boron. In contrast, the chem{[ArB_3O_4]^+} cation complex is characterized to be a weakly bound complex with a BO chain structure