Importance of Pd and Pt excited states in N 2 O capture and activation: A comparative study with Rh and Au atoms

Nitrous oxide (N 2 O) is an intermediate compound formed during catalysis occurring in automobile exhaust pipes. In this work, the N 2 O capture and activation by Pt and Pd atoms in the ground and excited states of many multiplicities are studied. Pt and Pd + N 2 O reactions are studied at multireference second‐order perturbation level of theory using C s symmetry. The PtN 2 O ( 1 A′, 5 A′, and 5 A″) species are spontaneously created from excited states. Only the 5 A′ and 5 A″ states exhibit N 2 O activation reaction paths when N 2 O approaches Pt end‐on by the N or O atoms side or side‐on yielding NO or N 2 as products, respectively. Pt + cations ground and excited states, capture N 2 O, although only Pt + ( 6 A′ and 6 A″) states show N 2 O activation yielding O and N 2 as products. In the Pd atom case, PdN 2 O ( 1 A′ and 5 A″) species are also spontaneously created from excited states. The 5 A″ state exhibits N 2 O activation yielding N 2 + O as products. Pd + cations in both ground and excited states capture N 2 O; however, only the [PdN 2 O] + ( 4 A′, 4 A″, 6 A′, and 6 A″) states in side‐on approaches and ( 6 A′) in end‐on approach activate the N 2 O and yield the N 2 bounded to the metal and O as product. The results obtained in this work are discussed and compared with previous calculations of Rh and Au atoms. The reaction paths show a metal–gas dative covalent bonding character. Löwdin charge population analyses for Pt and Pd active states show a binding done through charge donation and retrodonation between the metals and N 2 O. © 2013 Wiley Periodicals, Inc.