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A Terminal, Fluxional η 4 ‐Benzene Complex with a Thermally Accessible Triplet State is the Primary Photoproduct in the Intercyclobutadiene Haptotropism of (CpCo)phenylenes
Author(s) -
Albright Thomas A.,
Drissi Rima,
Gandon Vincent,
Oldenhof Sander,
OlobaWhenu Oluwakemi A.,
Padilla Robin,
Shen Hao,
Vollhardt K. Peter C.,
Vreeken Vincent
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201406211
Subject(s) - cyclobutadiene , chemistry , ring (chemistry) , cobalt , molecule , crystallography , benzene , reactivity (psychology) , photochemistry , stereochemistry , organic chemistry , medicine , alternative medicine , pathology
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.