Capturing the spin state diversity of iron(III)-aryl porphyrins OLYP is better than TPSSh

DFT calculations with a variety of exchange-correlation functionals including PW91 OLYP TPSSh B3LYP and B3LYP* have been carried out on the low-energy spin states of chloroiron(III) porphyrin and four aryliron(111) porphyrins viz Fe-III(P)Ph (S=1/2) Fe-III(P)C6F6 (S=5/2) Fe-III(P)(3 4 5 C6F3H2) (S=1/2) Fe-III(P)(2 4 6-C6F3H2) (S=5/2) where the expected spin states have been indicated within parentheses Qualitatively OLYP reproduces all the expected ground spin states B3LYP appears to have some difficulty yielding the observed sextet ground states B3LYP* TPSSh and PW91 all fall to reproduce the sextet ground states the latter two by rather large margins of energy As far as this study is concerned the overall performance of the functionals appears to be OLYP/OPBE>B3LYP>B3LYP*>> TPSSh>PW91/BLYP/BP86/TPSS (C) 2010 Elsevier Inc All rights reserved