Degenerate Pathways for Metallacycle Ring Inversions: A Common Phenomenon Consistent with the Principle of Microscopic Reversibility

Competing degenerate pathways for ring inversion in organometallic complexes are proposed to be ubiquitous examples that adhere to the principle of microscopic reversibility. The NMR spectra for ring inversion of two chromium arene dicarbonyl pyridyl chelates ([Cr­{η⁶-C₆H₅(CH₂)_<i>n</i>(2-Py-κ<i>N)</i>}­(CO)₂]; 2-Py = 2-pyridyl, <i>n</i> = 2 (<b>1</b>), and 3 (<b>2</b>)) and a manganese cyclopentadienyl dicarbonyl methyl sulfide chelate ([Mn­{η⁵-C₅H₄COC­(SCH₃)₂(SCH₃-κ<i>S</i>)}­(CO)₂] (<b>3</b>)) were characterized via variable-temperature NMR spectroscopy and DFT theoretical calculations