The Mössbauer spectrum of an intermediate spin (S= 1) four-co-ordinated (protoporphyrinato IX)iron(II) complex in a frozen aqueous solution of cetyltrimethylammonium bromide

Abstract

The Mössbauer spectrum of the four-co-ordinated haem, (protoporphyrinato IX)iron(II) monodispersed in an aqueous detergent solution of 5% cetyltrimethylammounium bromide (CTAB), is that of a typical intermediate spin (S= 1) system [the isomer shift is 0.57(2) mm s–1 and the quadrupole splitting (ΔEQ) is 1.44(2) mm s–1]; the results are comparable to those found in synthetic (porphyrinato)iron(II) analogues, the ΔEQ values follows the σ donating ability (basicity) of the porphyrin ligands and the two lines of the quadrupole doublet are of unequal intensity at 78 K.