Albright Thomas A, Drissi Rima, Gandon Vincent, Oldenhof Sander, Oloba-Whenu Oluwakemi A, Padilla Robin, Shen Hao, Vollhardt K Peter C, Vreeken Vincent
Department of Chemistry, University of Houston, Houston, TX 77204-5003 (USA).
Chemistry. 2015 Mar 16;21(12):4546-50. doi: 10.1002/chem.201406211. Epub 2015 Feb 2.
Low-temperature irradiation of linear [3]- and [4]phenylene cyclopentadienylcobalt complexes generates labile, fluxional η(4)-arene complexes, in which the metal resides on the terminal ring. Warming induces a haptotropic shift to the neighboring cyclobutadiene rings, followed by the previously reported intercyclobutadiene migration. NMR scrutiny of the primary photoproduct reveals a thermally accessible 16-electron cobalt η(2)-triplet species, which, according to DFT computations, is responsible for the rapid symmetrization of the molecules along their long axes. Calculations indicate that the entire haptotropic manifold along the phenylene frame is governed by dual-state reactivity of alternating 18-electron singlets and 16-electron triplets.
线性[3] - 和[4]亚苯基环戊二烯基钴配合物的低温辐照产生不稳定的、易变的η(4)-芳烃配合物，其中金属位于末端环上。升温会引发向相邻环丁二烯环的迁移异构化，随后是先前报道的环丁二烯间迁移。对初级光产物的核磁共振研究揭示了一种热可及的16电子钴η(2)-三重态物种，根据密度泛函理论计算，该物种负责分子沿其长轴的快速对称化。计算表明，沿亚苯基骨架的整个迁移异构化体系由交替的18电子单重态和16电子三重态的双态反应性控制。
