Fluorides of N, P, S, Se, and As

Fluorides of N, P, S, Se, and As. Extended-basis-set near-HF calculations on the. Y3E- a1 A, and 61E+ states of NF and the 2I1 states of NF+ and NF- were reported by O Hare and Wahl in 1971.350 NF is isoelectronic with O2 and has similar low-lying excited states. The calculations were carried out at R xp for the neutral molecules. Values of De derived with the use of semi-empirical correlation energies were in excellent agreement with experiment. The dipole moments of the low-lying states are different, unlike the case of NH, because of variations in bond length. The NF bond is slightly more ionic than the NH bond. Results for PF and its ions were also discussed.380 Little is known about this species experimentally. 

and AsF. These diatomics have only recently been synthesized, and there have been no calculations prior to 1970, when Wahl and co-workers reported near-HF wavefunctions.852 In the light of the known accuracy of these, it is suggested that the experimental appearance potentials are too high by 2eV. Thermodynamic calculations suggest that SF- and SeF- might be moderately stable. A later, more extensive study of the PE curves of SF has appeared.349 A large number of predictions were made for the spectroscopic constants. A very recent PE curve has been computed for SeF and its ions.353 The value of Do is estimated to be 3.2 0.1 eV. The computed fi is significantly different from the experimental value. The AsF mole- 

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