Molecular Structure, Spin Density Distribution, and Hyperfine Coupling Constants of the η{CuNO}11 Adduct in the ZSM-5 Zeolite: DFT Calculations and Comparison with EPR Data

Abstract

DFT calculations of the molecular structure of the intrazeolite η1{CuNO}11 adduct and the 14N and 17O hyperfine and 63Cu superhyperfine coupling constants were performed and compared with previous EPR results. The calculations confirmed the choice of signs adopted in the previous analysis of the experimental data and the character of the SOMO. The influence of the basis set and the exchange-correlation functional on the HFCC and the spin-density distribution was investigated and briefly discussed. The global repartition of the spin density over Cu (ρ = 0.11), N(ρ = 0.58), and O (ρ = 0.34) atoms determined from the Mulliken population analysis compared well with the experiment. The 14N hyperfine tensor was successfully reproduced with the LanL2DZ basis and BPW91 functional, whereas in the case of the 63Cu superhyperfine dipolar tensor T the agreement, except for that of the Tzz component, was less satisfactory because of an overestimated polarization of the 3dyz orbital, regardless of the computation level...