Very long-range isotope shifts in the proton NMR spectra of deuteriated haemins

Very long-range isotope shifts have been observed in the 500 MHz proton NMR spectra of several deuteriated haemins; these shifts are consistent with a redistribution of delocalised π spin density upon fractional resolution, owing to deuteriation, of the ground state orbital degeneracy of the low-spin iron(III) ion.