title: Pd(2)N(2), a proteiform molecule: Matrix isolation spectroscopy and density functional theory calculations.
abstract: The formation of Pd(2)N(2) from the cocondensation of effusive beams of Pd and N(2) in neon and argon matrices is evidenced by absorptions in the range of 2200-1800 cm(-1). In argon, selective irradiation in the near-infrared and visible ranges leads to interconversions between three structures, distinguished by the stretching frequency of the diatomic N(2): Bridged T-shaped (nu(NN) at 1990 cm(-1)), side on (nu(NN) at 2178 cm(-1)) and parallel (nu(NN) at 1823 cm(-1)). For the first two structures, the nu(NN) mode is also accompanied by another signal below 500 cm(-1). An extra feature close to 490 cm(-1), not sensitive to irradiation at lambda(irr)>400 nm and also assignable to a molecule with the same Pd:N(2) stoichiometry (2:1), corresponds to a centrosymmetrical Pd-N-N-Pd structure with an inactive nu(NN) mode close to 2141 cm(-1), as deduced from the observation of a weak signal close to 2630 cm(-1) associated with this species and assignable to the combination nu(NN)+nu(PdN). All these experimental data and their structural implications are fully supported by theoretical calculations [density functional theory (DFT)]. On the basis of this comparative study, we have obtained a reliable theoretical description of the spectroscopic data using the metageneralized gradient approximation functional within the unrestricted DFT (UDFT) formalism for all spin multiplets. We have also searched a stable electronic solution for each multiplet (particularly for the singlet state), in order to account for the nondynamic correlations.
authors.affiliation: Laboratoire de Dynamique, Interactions et Réactivité, UMR 7075 CNRS/UPMC, Université P. et M. Curie, Case courrier 49, bâtiment F74, 4, place Jussieu, 75252 Paris Cedex 05, France.
authors.forename: S M
authors.initials: SM
authors.lastname: Souvi
authors.forename: B
authors.initials: B
authors.lastname: Tremblay
authors.forename: J P
authors.initials: JP
authors.lastname: Perchard
authors.forename: M E
authors.initials: ME
authors.lastname: Alikhani
mesh_terms: D004583:Electrons; D009356:Neon / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D014732:Vibration
chemical_list: D009356:Neon; D010165:Palladium