Study On The Structure And Property Of Several Radicals

In recent years, radical has drawn an extensive attention, because it exists widely and its chemical property is quite active. As an important intermediate which participates numerous reductive reactions, it is important to study radical for the field of atmospheric chemistry, biology and medicine. In this paper, we studied aromatic ketone radicals ?? acetophenone with their substituent ramification of -fluorine, -methyl and -tert-butyl group and mercaptyl radicals CnH2n+1S·(n=2~5) and reported their structures of ground states, electron affinities, Vibrational frequencies, ionization affinities and proton affinities with G3 Theory and the Density Function Theory (B3LYP,BLYP,BP86 and BPW91). The basis sets are standard double-ζplus polarization adding a set of polarization and diffusing functions (denoted as DZP++).For aromatic ketone radicals, the ground states structure are Cs symmetry of 2A″electronic state, except for o-CH3 and o-C(CH3)3 with C1 symmetry of singlet electronic state. When the substitutional group is methyl or tert-butyl and the substituent position is meta- or para-, the structures of anion substitutional group have large changes compared with their corresponding neutrals. It is interesting to note that the energies of different position of substitutional groups are different. The energetic order for radicals is ortho-X >meta-X > para-X, and ortho-X?> para-X?> meta-X? for anions (X represents substituent groups of F, CH3, C(CH3)3). That is, the structures of para-position substituent for these radicals and the meta-position substituent for corresponding anions are more stable than those of other positions substituent. The predicted electron affinities by the B3LYP method has an excellent identical with available experimental data, the absolute average error is only 0.07 eV. The values obtained by the G3(MP3) method have worse results, the absolute average error is 0.33 eV.The ground states for all of mercaptyl radicals are Cs-symmetry except for b-C5H11S with C1 symmetry and t-C4H9S– with C3v symmetry. In bond parameters, the C-S bond length of CnH2n+1S·has confidential relation with the status of C atom which connected with S atom, when the C is primary carbon atom, the bond distance is 1.80 ? and secondary carbon atom correspond 1.81 ?, tertiary carbon atom correspond 1.82 ?. The theoretical electronic affinity compared with available experiment values, the method of G3, B3LYP and BP86 predicted the most reliable results, BPW91 and BLYP theory predicted worse reliable results.