Local Oxidation States in {FeNO}^6-8 Porphyrins: Insights from DMRG/CASSCF-CASPT2 Calculations.

ABSTRACT: A first DMRG/CASSCF-CASPT2 study of a series of paradigmatic {FeNO}⁶, {FeNO}⁷, and {FeNO}⁸ heme-nitrosyl complexes has led to substantial new insight as well as uncovered key shortcomings of the DFT approach. By virtue of its balanced treatment of static and dynamic correlation, the calculations have provided some of the most authoritative information available to date on the energetics of low- versus high-spin states of different classes of heme-nitrosyl complexes. Thus, the calculations indicate low doublet-quartet gaps of 1-4 kcal/mol for {FeNO}⁷ complexes and high singlet-triplet gaps of ≳20 kcal/mol for both {FeNO}⁶ and {FeNO}⁸ complexes. In contrast, DFT calculations yield widely divergent spin state gaps as a function

SUBMITTER: Phung QM 

PROVIDER: S-EPMC10716898 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature