TY - JOUR
T1 - Theoretical analysis of the structural and electronic properties of metalloporphyrin π-cation radicals
AU - Hirao, Hajime
AU - Shaik, Sason
AU - Kozlowski, Pawel M.
PY - 2006/5/11
Y1 - 2006/5/11
N2 - A method for analyzing the A 1u/A 2u contents of metalloporphyrin π-cation radicals is developed and applied to a series of unsubstituted planar metalloporphines (MPs) (M = Cr, Mn, Fe, Co, Ni, Cu, and Zn). The structures and electronic properties of the MPs and their cation radicals were calculated by density functional theory (DFT) and subsequently analyzed. It was found that the MPs with small core sizes have a tendency to form A 1u-type radicals, while the MPs with large core size have a preference for an A 2u-type. Neither of these pure-state species, however, is stable under the D 4h symmetry, and both radical cation types are subject to pseudo-Jahn - Teller (pJT) distortion. The pJT distortion leads to structures with lower symmetry and states that have mixed character with respect to the A 1u and A 2u components. The degree of mixing could be estimated by employing orbital projection technique or a complementary spin density decomposition. Both techniques produce very similar results, pointing out that the frontier orbital, which becomes empty upon electron removal, plays a critical role in determining electronic properties.
AB - A method for analyzing the A 1u/A 2u contents of metalloporphyrin π-cation radicals is developed and applied to a series of unsubstituted planar metalloporphines (MPs) (M = Cr, Mn, Fe, Co, Ni, Cu, and Zn). The structures and electronic properties of the MPs and their cation radicals were calculated by density functional theory (DFT) and subsequently analyzed. It was found that the MPs with small core sizes have a tendency to form A 1u-type radicals, while the MPs with large core size have a preference for an A 2u-type. Neither of these pure-state species, however, is stable under the D 4h symmetry, and both radical cation types are subject to pseudo-Jahn - Teller (pJT) distortion. The pJT distortion leads to structures with lower symmetry and states that have mixed character with respect to the A 1u and A 2u components. The degree of mixing could be estimated by employing orbital projection technique or a complementary spin density decomposition. Both techniques produce very similar results, pointing out that the frontier orbital, which becomes empty upon electron removal, plays a critical role in determining electronic properties.
UR - http://www.scopus.com/inward/record.url?scp=33744821370&partnerID=8YFLogxK
U2 - 10.1021/jp0558066
DO - 10.1021/jp0558066
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C2 - 16671680
AN - SCOPUS:33744821370
SN - 1089-5639
VL - 110
SP - 6091
EP - 6099
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 18
ER -