Multireference Ground and Excited State Electronic Structures of Free- versus Iron Porphyrin-Carbenes

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F20%3A00525077" target="_blank" >RIV/61388955:_____/20:00525077 - isvavai.cz</a>

Výsledek na webu

<a href="http://hdl.handle.net/11104/0309294" target="_blank" >http://hdl.handle.net/11104/0309294</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.inorgchem.0c00249" target="_blank" >10.1021/acs.inorgchem.0c00249</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Multireference Ground and Excited State Electronic Structures of Free- versus Iron Porphyrin-Carbenes

Popis výsledku v původním jazyce

Iron porphyrin carbenes (IPCs) are important reaction intermediates in engineered carbene transferase enzymes and homogeneous catalysis. However, discrepancies between theory and experiment complicate the understanding of IPC electronic structure. In the literature, this has been framed as whether the ground state is an open- vs closed-shell singlet (OSS vs CSS). Here we investigate the structurally dependent ground and excited spin-state energetics of a free carbene and its IPC analogs with variable trans axial ligands. In particular, for IPCs, multireference ab initio wave function methods are more consistent with experiment and predict a mixed singlet ground state that is dominated by the CSS (Fe(II) ← {:C(X)Y}0) configuration (i.e., electrophilic carbene) but that also has a small, non-negligible contribution from an Fe(III)–{C(X)Y}−• configuration (hole in d(xz), i.e., radical carbene). In the multireference approach, the “OSS-like” excited states are metal-to-ligand charge transfer (MLCT) in nature and are energetically well above the CSS-dominated ground state. The first, lowest energy of these “OSS-like” excited states is predicted to be heavily weighted toward the Fe(III)–{C(X)Y}−• (hole in d(yz)) configuration. As expected from exchange considerations, this state falls energetically above a triplet of the same configuration. Furthermore, potential energy surfaces (PESs) along the IPC Fe–C(carbene) bond elongation exhibit increasingly strong mixings between CSS/OSS characters, with the Fe(III)–{C(X)Y}−• configuration (hole in d(xz)) growing in weight in the ground state during bond elongation. The relative degree of electrophilic/radical carbene character along this structurally relevant PES can potentially play a role in reactivity and selectivity patterns in catalysis. Future studies on IPC reaction coordinates should evaluate contributions from ground and excited state multireference character.

Název v anglickém jazyce

Multireference Ground and Excited State Electronic Structures of Free- versus Iron Porphyrin-Carbenes

Popis výsledku anglicky

Iron porphyrin carbenes (IPCs) are important reaction intermediates in engineered carbene transferase enzymes and homogeneous catalysis. However, discrepancies between theory and experiment complicate the understanding of IPC electronic structure. In the literature, this has been framed as whether the ground state is an open- vs closed-shell singlet (OSS vs CSS). Here we investigate the structurally dependent ground and excited spin-state energetics of a free carbene and its IPC analogs with variable trans axial ligands. In particular, for IPCs, multireference ab initio wave function methods are more consistent with experiment and predict a mixed singlet ground state that is dominated by the CSS (Fe(II) ← {:C(X)Y}0) configuration (i.e., electrophilic carbene) but that also has a small, non-negligible contribution from an Fe(III)–{C(X)Y}−• configuration (hole in d(xz), i.e., radical carbene). In the multireference approach, the “OSS-like” excited states are metal-to-ligand charge transfer (MLCT) in nature and are energetically well above the CSS-dominated ground state. The first, lowest energy of these “OSS-like” excited states is predicted to be heavily weighted toward the Fe(III)–{C(X)Y}−• (hole in d(yz)) configuration. As expected from exchange considerations, this state falls energetically above a triplet of the same configuration. Furthermore, potential energy surfaces (PESs) along the IPC Fe–C(carbene) bond elongation exhibit increasingly strong mixings between CSS/OSS characters, with the Fe(III)–{C(X)Y}−• configuration (hole in d(xz)) growing in weight in the ground state during bond elongation. The relative degree of electrophilic/radical carbene character along this structurally relevant PES can potentially play a role in reactivity and selectivity patterns in catalysis. Future studies on IPC reaction coordinates should evaluate contributions from ground and excited state multireference character.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2020

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Inorganic Chemistry

ISSN

0020-1669

e-ISSN

—

Svazek periodika

59

Číslo periodika v rámci svazku

13

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

9

Strana od-do

8707-8715

Kód UT WoS článku

000548456300011

EID výsledku v databázi Scopus

2-s2.0-85087532519