  A series of experiments demonstrate that strong light-matter coupling between
vibrational excitations in isotropic solutions of molecules and resonant
infrared optical microcavity modes leads to modified thermally-activated
kinetics. However, Feist and coworkers [\emph{Phys. Rev. X.}, \textbf{9},
021057(2019)] have recently demonstrated that, within transition state theory,
the effects of strong light-matter coupling with reactive modes are
electrostatic and essentially independent of light-matter resonance or even of
the formation of vibrational polaritons. To analyze this puzzling theoretical
result in further detail, we revisit it under a new light, invoking a normal
mode analysis of the transition state and reactant configurations for an
ensemble of an arbitrary number of molecules in a cavity, obtaining simple
analytical expressions that produce similar conclusions as Feist. While these
effects become relevant in optical microcavities if the molecular dipoles are
anisotropically aligned, or in cavities with extreme confinement of the photon
modes, they become negligible for isotropic solutions in microcavities. It is
concluded that further studies are necessary to track the origin of the
experimentally observed kinetics.

Chemical Physics;Mesoscale and Nanoscale Physics