Molecular Structure, Spin Density Distribution, and Hyperfine Coupling Constants of theη1{CuNO}11Adduct in the ZSM-5 Zeolite:  DFT Calculations and Comparison with EPR Data

What is it about?

DFT calculations of the molecular structure of intrazeolite h1{CuNO}11 adduct, 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 previous analysis of the experimental data and the character of 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. Global repartition of the spin density over Cu (0.11), N (0.58) and O (0.34) atoms determined from the Mulliken population analysis compared well with the experiment. The 14N hyperfine tensor was succesfuly reproduced with the LanL2DZ basis and BPW91 functional, while in the case of 63Cu superhyperfine dipolar tensor T the agreement, except of the Tzz component, was less satisfactory due to an overestimated polarization of the 3dyz orbital, regardless of the computation level. For the calculation of aiso (Cu), since LanL2DZ treats inner electrons with the effective core potential, a 6–311G(df) basis set appeared to be the most appropriate, leading to an excellent accordance between the experimental and calculated values.

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