p-Carborane Conjugation in Radical Anions of Cage-Cage and Cage-Phenyl Compounds

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388963%3A_____%2F18%3A00489518" target="_blank" >RIV/61388963:_____/18:00489518 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1021/acs.jpca.7b10885" target="_blank" >http://dx.doi.org/10.1021/acs.jpca.7b10885</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.jpca.7b10885" target="_blank" >10.1021/acs.jpca.7b10885</a>

Jazyk výsledku

angličtina

Název v původním jazyce

p-Carborane Conjugation in Radical Anions of Cage-Cage and Cage-Phenyl Compounds

Popis výsledku v původním jazyce

Optical electron transfer (intervalence) transitions in radical anions of p-carborane oligomers attest to delocalization of electrons between two p-carboranes cages or a p-carborane and a phenyl ring. Oligomers of the 12 vertex p-carborane (C2B10H12) cage, [12], with up to 3 cages were synthesized, as well as p-carboranes with one or two trimethylsilylphenyl groups, [6], attached to the carbon termini. Pulse radiolysis in tetrahydrofuran produced radical anions, determined redox potentials by equilibria and measured their absorption spectra. Density functional theory computations provided critical insight into the optical electron transfer bands and electron delocalization. One case, [6-12-6], showed both Robin Day class II and III transitions. The class III transition resulted from a fully delocalized excess electron across both benzene rings and the central p-carborane, with an electronic coupling H-ab = 0.46 eV between the cage and either benzene. This unprecedented finding shows that p-carborane bridges are not simply electron withdrawing insulators. In other cases with more than similar to 1/2 of the excess electron localized on a [12], large cage distortions were triggered, producing a partially open cage with a nido-like structure. This resulted in class II transitions with similar H-ab but massive reorganization energies. The computations also predicted delocalization in radical cations, but complexities in cation formation allowed only tentative experimental support of the predictions. The results with anions provide clear evidence for carborane conjugation that might be exploited in molecular wire materials, which are classically composed of all pi-conjugated molecules.

Název v anglickém jazyce

p-Carborane Conjugation in Radical Anions of Cage-Cage and Cage-Phenyl Compounds

Popis výsledku anglicky

Optical electron transfer (intervalence) transitions in radical anions of p-carborane oligomers attest to delocalization of electrons between two p-carboranes cages or a p-carborane and a phenyl ring. Oligomers of the 12 vertex p-carborane (C2B10H12) cage, [12], with up to 3 cages were synthesized, as well as p-carboranes with one or two trimethylsilylphenyl groups, [6], attached to the carbon termini. Pulse radiolysis in tetrahydrofuran produced radical anions, determined redox potentials by equilibria and measured their absorption spectra. Density functional theory computations provided critical insight into the optical electron transfer bands and electron delocalization. One case, [6-12-6], showed both Robin Day class II and III transitions. The class III transition resulted from a fully delocalized excess electron across both benzene rings and the central p-carborane, with an electronic coupling H-ab = 0.46 eV between the cage and either benzene. This unprecedented finding shows that p-carborane bridges are not simply electron withdrawing insulators. In other cases with more than similar to 1/2 of the excess electron localized on a [12], large cage distortions were triggered, producing a partially open cage with a nido-like structure. This resulted in class II transitions with similar H-ab but massive reorganization energies. The computations also predicted delocalization in radical cations, but complexities in cation formation allowed only tentative experimental support of the predictions. The results with anions provide clear evidence for carborane conjugation that might be exploited in molecular wire materials, which are classically composed of all pi-conjugated molecules.

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

2018

Kód důvěrnosti údajů

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

Název periodika

Journal of Physical Chemistry A

ISSN

1089-5639

e-ISSN

—

Svazek periodika

122

Číslo periodika v rámci svazku

3

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

13

Strana od-do

798-810

Kód UT WoS článku

000423653100007

EID výsledku v databázi Scopus

2-s2.0-85041180410