SCF molecular orbitals and the photoelectron spectrum of 5,5-dimethyl-Δ3-1,3,4-oxadiazolin-2-one Academic Article uri icon

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abstract

  • CNDO/2 Frontier molecular orbital densities, ionization potentials (IP's), and electronic transition energies were calculated for the title compound (2b) and the 5,5-diprotio (2a), and 5,5-difluoro (2d) analogs. Bond lengths and angles were not optimized but rather taken from a crystal structure of the 2-imino System 3, with an assumed carbonyl bond length of Rco = 1.19 Å. This value is supported by a high infrared stretching frequency (1835 cm−1), X-ray crystal data of 3, and the effect of Rco variation on calculated IP's. The first three bands of the photoelectron spectrum of 2b were assigned as nN (10.20 eV), π1 (11.52eV), and nco (13.26 eV) (vertical IP's). This unusually large nco IP is attributed to an inductive effect of the neighbouring strongly electron withdrawing azo group. The IP's obtained by CNDO/2 calculation (12.81, 13.37, and 15.15) are 1.5 to 2.5 eV higher than the experimental values, well within the predictive capability of the method, establishing that this theoretical treatment gives a good representation of the MO's of 2b.

publication date

  • May 15, 1978