Theoretical studies on hydrogen activation by iridium dimers

Abstract

The basic and fundamental mechanisms governing the catalytic reaction of small iridium clusters with H2 are presented here with the purpose to determine its behavior in hydrogenation reactions. The iridium dimer/s lowest states in interaction with H2 potential energy surface were obtained using ab initio multiconfigurational self-consistent-field calculations (MC–SCF), with relativististic pseudopotentials. The electronic correlation contribution was included by configurations interaction (CI) calculations, which considered a variational part plus a second-order perturbative part. The Ir2+H2 reactions were developed in the C2v symmetry. The Ir2's five lowest electronic states were determined, 5Πg, 3Πg, 1Σg+, 3Σu+, and 5Σg, and studied when reacted with H2. It was found that the iridium dimer, in these five states, might capture and break the HH bond, spontaneously in certain cases and after surmounting activation barriers in other cases. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 1029–1035, 1998