Five iron complexes of the Fe(PDP) family, giving rise to the low-spin (S = 1/2) and high-spin (S = 3/2) perferryl oxygentransferring intermediates, have been screened in the CÀ H oxidation of the bulky steroidal substrate (3aR)-(+)-sclareolide with H 2 O 2 . The regioselectivity of oxidation (preferentially at the C2 methylenic site) increases when passing from the catalyst systems exhibiting more reactive, low-spin perferryl oxygentransferring species to those featuring their less reactive, highspin counterparts. Furthermore, the C2 hydroxylation chemoselectivity increases in the same order, being the highest for the least reactive intermediate in the series; this observation is explained in terms of the more product-like transition state.