THEORETICAL-STUDIES OF THE PT2-H-2 INTERA CTION

The capture and activation of molecular hydrogen by the platinum dimer has been studied by perturbative and variational MRCI calculations, u sing relativistic pseudopotentials. Both singlet and triplet A1 states are found to be efficients in the activation of the H-H bond. The res ults are compared with those previously obtained for the Pt monomer, f or which only the singlet states are active. A Pt/H=1/1 relationship i s obtained, in agreement with the experimental chemisorption results o f H-2 in Pt catalysts. Also it is found that the reaction channel for the H-Pt dissociation is closed since the systems present large energi es barriers. At the minimum the hydrogen molecule is dissociated and f orms a weak Pt-H bond.