The infrared absorption of KH2F3 and KD2F3in the solid state was measured between 4 000 and 200 cm−1 The observed bands can be assigned to the stretching and bending modes of the bent H2F3− ion. A normal coordinate analysis was carried out to determine the Urey–Bradley force constants. The results suggest that the hydrogen atoms are not exactly halfway between two fluorine atoms, contrary to the case of the HF2− ion.Les spectres infrarouges de KH2F3 et KD2F3 à l'état solide ont été mesurés entre 4 000 et 200 cm−1 afin d'identifier les vibrations fondamentales de l'anion H2F3−. Les constantes de forces de rappel selon le modèle de Urey–Bradley ont pu être déterminées par analyse des coordonnées normales. Les résultats indiquent que les atomes d'hydrogène ne sont pas exactement à mi-chemin entre deux atomes de fluor, contrairement au cas de l'ion HF2−.

Acid 743 our calculation (~10 kcal/mol) and the experimental value (~20 kcal/mol) of Zittel et al. In any case, the results of the calculations presented here cannot be reconciled with a singlet-triplet separation in methylene of 19.5 ± 0.7 kcal/mol deduced by Zittel et al. from their experiments. VI. ConclusionThe use of the two-configuration singlet reference state is shown to produce results in agreement with those of the oneconfiguration singlet, if the estimated quadruple excitations corrections are taken into account. A trend is observed which indicates that the 3P carbon atom, the 2 CH radical, and 1Ai methylene are all related, while 5S carbon, 4 ~CH, and 3Bj CH2 are also related. Accurate calculations for C and CH show C(3P) and CH(2n) too high by ~2 kcal/mol relative to C(5S) and € (4 ~), respectively. This indicates that the computed large-basis 1A1 state of methylene is still too high relative to 3B|. Therefore, the correct separation is most likely somewhat smaller than our lowest computed value of 10.6 kcal/mol, and may possibly be as low as 9 kcal/mol.

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19, P. Box 380, Yugoslavia) Summary Using a minimal basis Hartree-Fock crystal orbital formalism for five structurally different infinite polyene (polyacetylene) models i t is concluded that, besides the all-trans configuration, other structures may be energetically equal or even more probable.

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