Matrix Isolation Infrared Spectroscopic and Theoretical Study of Transition Metal Dioxide−Acetylene Complexes

Abstract

The reactions of transition metal dioxides (MnO 2 and FeO 2 ) with acetylene molecules have been studied using matrix isolation infrared absorption spectroscopy. The metal dioxide molecules were prepared by the reactions of laser-ablated metal atoms with dioxygen. In solid argon, the MnO 2 and FeO 2 molecules reacted with C 2 H 2 to form the (η 2 -C 2 H 2 )MnO 2 and (η 2 -C 2 H 2 )FeO 2 complexes spontaneously on annealing. Both complexes were predicted to have low-spin ground states ( 1 A 1 for (η 2 -C 2 H 2 )FeO 2 , 2 A 1 for (η 2 -C 2 H 2 )MnO 2 ) with C 2 v symmetry. In addition, evidence is also presented for the formation of Mn(H)CCO and Fe(H)CCO molecules upon UV-visible irradiation. The product absorptions were identified by isotopic substitution as well as density functional calculations of isotopic frequencies.