An iron-catalyzed C-H/N-H alkyne annulation was realized by using a customizable clickable triazole amide under exceedingly mild reaction conditions. A unifying mechanistic approach combining experiment, spectroscopy, kinetics, and computation provided strong support for facile C-H activation by a ligand-to-ligand hydrogen transfer (LLHT) mechanism. Combined Mössbauer spectroscopic analysis and DFT calculations were indicative of high-spin iron(II) species as the key intermediates in the C-H activation manifold.
Keywords: C−H activation; Mössbauer spectroscopy; density functional calculations; iron; reaction mechanisms.
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