SURFACE LOCAL IONIZATION ENERGIES AND ELECTROSTATIC POTENTIALS OF THE CONJUGATE BASES OF A SERIES OF CYCLIC HYDROCARBONS IN RELATION TO THEIR AQUEOUS ACIDITIES

• We have computed surface local ionization energies [IBAR(s)(r)] and electrostatic potential minima (V(min)) for the conjugate bases of a series of cyclic hydrocarbons, using an ab initio self-consistent field-molecular orbital approach. Our IBAR(s)(r) and V(min) results are discussed in relation to the acidities of the parent hydrocarbons. A good correlation exists between experimentally determined pK(a) values and the lowest surface IBAR(r) values [IBAR(s,min)], providing a predictive capability for estimating unknown pK(a)'S. The electrostatic potential minima, V(min), do not relate as well to pK(a) as does IBAR(s,min). Using our IBAR(s,min) versus pK(a) correlation, we predict the pK(a)'s of the strained cage polyhedranes cubane, triprismane, and tetrahedrane to be 36, 32, and 26, respectively.

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NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

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