Oxygen binding to iron–porphyrin: A density functional study using both LSD and LSD+GC schemes
✍ Scribed by Carme Rovira; Michele Parrinello
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 201 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
Equilibrium structures of iron᎐porphyrin FeP and its O complex, 2 computed with Car᎐Parrinello molecular dynamics, are in excellent agreement with experimental data on synthetic heme models. Geometry optimization can affect significantly the relative energies among spin states of these systems. The Fe-O bond, best described as Fe III -O y , increases its strength from 9 to 15 kcalrmol upon binding an 2 Ž . imidazole axial ligand Im . Our results are consistent with an open-shell singlet as the Ž .Ž . ground state of FeP Im O , in competition with a low-lying closed-shell singlet state 2 and, as the FeOO angle increases, with a triplet state. The conformation in which the imidazole plane and the O-O axis projection lie in the same N-Fe-N porphyrin quadrant is found to be stable, although easy rotation of the O molecule around the 2 Fe-O axis at room temperature is predicted. Comparison of the performance between Ž .
Ž the local spin density approximation LSD and the gradient-corrected scheme LSD q . GC is provided.