Wang Jin, Burdzinski Gotard, Zhu Zhendong, Platz Matthew S, Carra Claudio, Bally Thomas
Department of Chemistry, The Ohio State University, Columbus, OH 43210, USA.
J Am Chem Soc. 2007 Jul 4;129(26):8380-8. doi: 10.1021/ja071325j. Epub 2007 Jun 13.
p-biphenylyl, o-biphenylyl, and 1-naphthyl azides were deposited in argon at low temperature in the presence and absence of HCl. In the absence of HCl, the known electronic and vibrational spectra of the corresponding triplet nitrenes, azirines, and didehydroazepines were observed, whereas in the presence of HCl, photolysis of these azides produces new electronic spectra assigned to the corresponding nitrenium cations. For p-biphenylyl azide the resulting spectrum of the nitrenium ion is very similar to the previously observed solution-phase spectrum of this species. The vibrational spectrum of this cation was recorded for the first time. Spectroscopic evidence for the previously unknown o-biphenylylnitrenium cation and 1-naphthylnitrenium cation are provided. The spectra of p- and o-biphenylylnitrenium cations and 1-naphthylnitrenium cation are well reproduced by CASSCF and CASPT2 calculations. The same nitrenium cations were detected in solution by femtosecond time-resolved laser flash photolysis of the appropriate azides in 88% formic acid. The transient spectra of the nitrenium cations recorded in solution are in good agreement with the spectra obtained in HCl matrices. The rates of formation of these cations equal the rates of decay of the singlet nitrenes in 88% formic acid and are as follows: p-biphenylyl (taugrowth = 11.5 ps), o-biphenylyl (taugrowth = 7.7 ps), and 1-naphthylnitrenium cations (taugrowth = 8.4 ps). The decay lifetimes of p- and o-biphenylylnitrenium cations are 50 and 27 ns, respectively. The decay lifetimes of 1-naphthylnitrenium cation is 860 ps in 88% formic acid.
对 - 联苯基叠氮化物、邻 - 联苯基叠氮化物和1 - 萘基叠氮化物在有和没有HCl存在的情况下于低温氩气中沉积。在没有HCl的情况下，观察到了相应三线态氮烯、氮丙环和二脱氢氮杂卓的已知电子光谱和振动光谱，而在有HCl存在的情况下，这些叠氮化物的光解产生了归属于相应氮鎓阳离子的新电子光谱。对于对 - 联苯基叠氮化物，所得氮鎓离子的光谱与该物种先前观察到的溶液相光谱非常相似。首次记录了该阳离子的振动光谱。提供了关于先前未知的邻 - 联苯基氮鎓阳离子和1 - 萘基氮鎓阳离子的光谱证据。对 - 和邻 - 联苯基氮鎓阳离子以及1 - 萘基氮鎓阳离子的光谱通过CASSCF和CASPT2计算得到了很好的再现。通过在88%甲酸中对适当叠氮化物进行飞秒时间分辨激光闪光光解，在溶液中检测到了相同的氮鎓阳离子。溶液中记录的氮鎓阳离子的瞬态光谱与在HCl基质中获得的光谱吻合良好。这些阳离子的形成速率等于88%甲酸中单线态氮烯的衰减速率，具体如下：对 - 联苯基（τ增长 = 11.5 ps）、邻 - 联苯基（τ增长 = 7.7 ps）和1 - 萘基氮鎓阳离子（τ增长 = 8.4 ps）。对 - 和邻 - 联苯基氮鎓阳离子的衰减寿命分别为50和27 ns。1 - 萘基氮鎓阳离子在88%甲酸中的衰减寿命为860 ps。
