Solvation and stabilization of palladium nanoparticles in phosphonium-based ionic liquids: a combined infrared spectroscopic and density functional theory study.
Phys Chem Chem Phys
; 16(38): 20672-80, 2014 Oct 14.
Article
em En
| MEDLINE
| ID: mdl-25158763
ABSTRACT
Analysis of infrared spectra of palladium nanoparticles (NPs) immersed in the tri-tert-butyl-R-phosphonium-based ionic liquids (ILs) demonstrates that both cations and anions of the ILs interact with the NPs. According to quantum-chemical simulations of these interactions, the binding energy of anions to the Pd6 cluster, taken as a minimal-size model of the NPs, increases from â¼6 to â¼27 kcal mol(-1) in the order [PF6](-)≈ [BF4](-) < [Tf2N](-) < [OTf](-) < [Br](-)⪠[TFA](-). In contrast, the binding energy for all types of the [Bu(t)3PR](+) cations slightly varies at about â¼22 kcal mol(-1) only moderately depending on the choice of the R moiety (n-pentyl, 2-hydroxyethyl, 2-methoxyethyl, 2-ethoxy-2-oxoethyl). As a result, the energies of interaction between a Pd6 cluster and various ion pairs, formed by the abovementioned counter-ions, follow the order found for the anions and vary from â¼24 to â¼47 kcal mol(-1). These values are smaller than the energy of addition of a Pd atom to a Pdn cluster (â¼58 kcal mol(-1)), which suggests kinetic stabilization of the NPs in phosphonium-based ILs rather than thermodynamic stabilization. The results are qualitatively similar to the trends found earlier for interactions between palladium clusters and components of imidazolium-based ILs, in spite of much larger contributions of the London dispersion forces to the binding of the [Bu(t)3PR](+) cations to the cluster (up to 80%) relative to the case of 1-R-3-methylimidazolium cations (up to 40%).
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Paládio
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Fosfinas
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Espectrofotometria Infravermelho
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Líquidos Iônicos
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Nanopartículas Metálicas
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Modelos Químicos
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article