Multi-temperature Möossbauer data and C–N/O stretching frequencies of [K(222)][Fe(TPP)(CN)], two forms of [K(222)]2[Fe(TPP)(CN)2], [K(222)] 2[Fe(TTP)(CN) 2] and [K(222)][Fe(TPP)(CN)(1-MeIm)], and the comparable values for [Fe(OEP)(CO)],[20] [Fe(OEP)(CO) 2],[20] [Fe(OEP)(CO)(1-MeIm)][24] and [Fe(TPP)(CO)(1-MeIm)].[24] ΔEq and δ values in mm/s.