TABLE 2: Values of ionisation energy (I), electron affinity (A) absolute electronegativity (chi) and absolute hardness (eta) used in the calculations of dN c and dE c .
a The alkene ionisation energies are from Masclet et al.33 apart from 3-fluoropropene, which was estimated by adding the calculated difference in ionisation energy between it and propene (using Mopac 6.0, using the AM1 Hamiltonian 34 ), to the experimental value for propene. b Experimental values from Jordan and Burrow 35 (except for 1-butene 36 ). c For the alkenes, a reasonable correlation was obtained between the energy of the lowest unoccupied molecular orbital (from Mopac 6.0, AM1 Hamiltonian 34 ) and experimentally determined electron affinities:35,36 A(eV) = 1.77xLUMO AM1 (eV) - 4.39(eV) (r = 0.93, standard error of the estimated affinities = 0.74 eV) which was used to estimate the unmeasured electron affinities via LUMO values calculated using Mopac 6.0. d The ionisation energies and electron affinities were calculated by Jonsson 37 using Mopac 6.0 at the RHF level with the AM1 Hamiltonian (with configuration interaction (C.I.) = 1),34 except for the values for i-C 3 H 7 O 2 , C 2 H 3 C(O)O 2 , HOC 3 H 6 O 2 , HOCH 2 O 2 and C 3 H 5 O 2 which were calculated by the same technique for this work. The electron affinities for the radicals were taken as the ionisation energy for the corresponding anions.
I (eV)a A (eV) chi (eV) eta (eV)
2,3-dimethyl-2-butene 8.271 -2.27b 3.00 5.27 2-methyl-2-butene 8.682 -2.24b 3.22 5.46 trans-2-hexene 8.969 -2.07c 3.45 5.52 cis-2-hexene 8.969 -2.07c 3.45 5.52 trans-2-pentene 9.036 -2.09c 3.48 5.56 cis-2-pentene 9.036 -2.08c 3.47 5.56 trans-2-butene 9.122 -2.22b 3.45 5.67 cis-2-butene 9.124 -2.10b 3.51 5.61 2-methyl-1-butene 9.148 -2.08b 3.53 5.62 2-methylpropene 9.239 -2.19c 3.52 5.71 1-hexene 9.478 -1.93c 3.78 5.70 1-pentene 9.524 -1.93c 3.80 5.73 3-methyl-1-butene 9.533 -1.93c 3.80 5.73 1-butene 9.625 -1.90b 3.86 5.76 propene 9.744 -1.99b 3.88 5.87 ethene 10.515 -2.50b 4.37 6.15 3-fluoropropene 10.045 -1.78c 3.77 6.27 CH3C(O)O2 11.58d 2.75d 7.16 4.42 CH3O2 11.18d 1.21d 6.19 4.98 HO2 11.69d 0.81d 6.25 5.44 i-C3H7O2 11.00d 1.40d 6.20 4.80 t-C4H9O2 10.92d 1.48d 6.20 4.72 C2H3C(O)O2 11.49d 2.90d 7.19 4.30 HOC3H6O2 10.86d 2.02d 6.44 4.42 HOCH2O2 11.43d 1.96d 6.70 4.73 C3H5O2 11.14d 1.60d 6.37 4.77