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

DFT calculations of the molecular structure of the intrazeolite η 1 {CuNO} 11 adduct and the 14 N and 17 O hyperfine and 63 Cu 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 14 N hyperfine tensor was successfully reproduced with the LanL2DZ basis and BPW91 functional, whereas in the case of the 63 Cu superhyperfine dipolar tensor T the agreement, except for that of the T zz component, was less satisfactory because of an overestimated polarization of the 3d yz orbital, regardless of the computation level. For the calculation of a iso (Cu), because LanL2DZ treats inner electrons with the effective core potential, a 6-311G(df) basis set appeared to be the most appropriate, leading to excellent agreement between the experimental and calculated values.