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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Iminocyclohexadienylidenes: Carbenes or Diradicals? The Hetero-Wolff Rearrangement of Benzotriazoles to Cyanocyclopentadienes and 1H-Benzo[b]azirines
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Iminocyclohexadienylidenes: Carbenes or Diradicals? The Hetero-Wolff Rearrangement of Benzotriazoles to Cyanocyclopentadienes and 1H-Benzo[b]azirines

机译：Iminocyclohexadienylidenes：carbenes或diradicals？ 苯并二唑对氰基苯并二烯的杂交 - Wolff重排和1H-苯并[B] Azirines

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The thermal rearrangements of benzotriazole 1 to fulvenimine 4 and 1H-benzazirine 7 are investigated at DFT and CASPT2 levels of theory. Ring opening of benzotriazole 1 to 2-diazo-cyclohexadienimine 2 followed by N-2 elimination affords Z- and E-2-iminocyclohexadienylidenes 3, which have triplet ground states ((3)A ''). The open-shell singlet (OSS) ((1)A '') and closed-shell singlet (CSS) ((1)A') of 3 lie similar to 15 and 40 kcal/mol higher in free energy, respectively. The OSS 3 ((1)A '') is best described as a 1,3-diradical, whereas the CSS ((1)A') has the character of a carbene. A hetero-Wolff rearrangement of OSS 3 yields fulvenimine 4, which is a precursor of cyanocyclopentadiene 5, with a calculated activation barrier of 38 kcal/mol at the CASPT2(8,8) level, whereby there is a surface crossing from the OSS to the CSS near the transition state. The barrier for cyclization to 1H-benzo[b]azirine 7 is only similar to 13 kcal/mol. Therefore, reaction paths involving the singlet iminocyclohexadienylidene diradicals 3 will necessarily cause equilibration with 1H-benzazirine 7 prior to ring contraction to iminofulvene 4 and cyanocyclopentadiene 5, in agreement with experimental observations based on C-13 labeling. The thermolysis of 1-acetylbenzotriazole 7 leads to the analogous N-acetyl-diazocyclo-hexadienimines 8, N-acetyliminocyclohexadienylidene diradicals 9, and N-acetylfulvenimine 10. The E-N-acetyliminocyclohexadienylidene E9 ring closes to the N-acetyl-1H-benzazirine 11 prior to ring contraction to N-acetylfulvenimine 10, and the Z-N-acetyl-2-diazocyclohexadienimine Z8 ring closes to 2-methylbenzoxazole 12. 1H-benzazirines are predicted to be spectroscopically observable species.
机译：在DFT和CASPT2理论水平下研究了苯并三唑1至蜂鸣中4和1H-苯嗪7的热重排。苯并三唑1至2-二氮杂环己二烯亚胺2的环开口，然后得到N-2消除，得到Z-和E-2-酰上Clohexadi烯基约3，其具有三重态地（（3）A''）。 3位的开口壳体（（1）''）和闭合壳体（（1）'）和闭合壳体（（1）'）分别在自由能中的较高较高的15和40千卡/摩尔。 OSS 3（（1）A''）最好被描述为1,3-Diradical，而CSS（（1）A'）具有卡贝的特征。 OSS 3的杂湿度重排产生蜂鸣4，其是豆鳞型二烯5的前体，在Caspt2（8,8）水平上具有38千卡/摩尔的计算活化屏障，从而从OSS横穿过渡状态附近的CSS。环化至1H-苯并[B]亚嗪7的屏障仅类似于13千卡/摩尔。因此，涉及单次氨基环己二烯基二甲苯基的反应路径3将在与基于C-13标记的实验观察开始之前，在与咪福芳烯4和氰基氰化二烯5的收缩之前，必须导致与亚苯齐嗪7的平衡。 1-乙酰苯并二唑7的热解导致类似的N-乙酰基 - 二氮杂环-Hexadimines 8，N-乙酰嘧啶膦己二烯基二甲苯二，乙酰嘧啶嘧啶胺10.苯乙酰基嘧啶己二烯基乙烯e9环在先前闭合到N-乙酰基-1H-苯并嗪11将收缩到N-乙酰胆量10，并且Zn-乙酰基-2-二氮杂环己二烯Z8环关闭至2-甲基苯并恶唑12.预测1H-苯并吡啶是光谱可观察的物种。

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