Isotope effect profiles in the N-demethylation of N,N-dimethylanilines: a key to determine the pK(a) of nonheme Fe(III)-OH complexes.

N-demethylation of N, N-dimethylanilines promoted by [(N4Py)Fe-IV=O](2+) occurs by an electron transfer-proton transfer (ET-PT) mechanism with a rate determining PT step. From the bell- shaped curve of the KDIE profile it has been estimated that the pK(a) of [(N4Py) Fe-III-OH](2+) is 9.7.