With the ensemble of vibrationally distorted structures in hand, the changes in Mössbauer parameters can be correlated to displacements along the normal coordinates of the [Fe(TPP)(2-MeHIm)] complex. Correlating these changes to individual normal coordinates does not deliver satisfactory results, and therefore, we turned to a multicomponent fitting procedure, in which the normal coordinates are used as basis functions to obtain collective motions that represent the observed changes. Methodological details are given in the SI, sections S3 and S4.