N-亚硝基吲哚系列化合物及其自由基负离子在乙腈介质中N—NO键断裂能的测定

Determination of N—NO Bond Dissociation Energies of N-Nitrosoindoles and Their Radical Anions in Acetonitrile

利用滴定量热技术并结合适当的热力学循环测定了乙腈溶液中7个取代的N-亚硝基吲哚化合物中N—NO键的异裂能和均裂能,能量范围分别为206.1～246.2 kJ/mol和119.1～124.6 kJ/mol.表明N-亚硝基吲哚均裂释放NO自由基（NO.）比异裂释放NO正离子（NO^＋）要容易得多,通过热力学循环得到的相应自由基负离子中N—NO键的异裂能和均裂能的能量范围分别为25.5～34.4和5.0～40.5 kJ/mol,表明所研究化合物的自由基负离子在室温下很不稳定.

The heterolytic and homolytic N—NO bond dissociation energies of seven N-nitrosoindole derivatives were evaluated by using titration calorimetry and relative thermodynamic cycles. The energetic scales of the heterolytic and homolytic N—NO bond dissociation energies of N-nitrosoindoles cover the ranges from 206. 1 to 246.2 kJ/mol and from 119.1 to 124. 6 kJ/mol, respectively, which indicates that N-nitrosoindoles are much easier to release a NO radical（NO^＋） rather than a NO cation（NO^＋）. The estimation of the hetero- lytic and homolytic （N—NO） ^- ＋ bond dissociation energies of the N-nitrosoindoles radical anions gives the energetic ranges from 25.5 to 33.4 k J/tool and from 5.0 to 40.5 k J/tool for the （N-NO） ^- ＋ bond homolysis and heterolysis, respectively, which means that N-nitrosoindole radical anions are unstable at room temperature.