Fullerénvegyületek Mössbauer-spektroszkópiája

Research output: Article

Abstract

We have measured the 193Ir Mössbauer spectrum of the adduct of chlorocarbonylbis(triphenylphosphine)iridium (IrCl(CO)(PPh3)2) with buckminsterfullerene (C60) and, for comparison, remeasured the spectra of both the parent compound and its adduct with tetracyanoethylene, (TCNE). In an other series of measurements di-μ-chloro-bis (1,5-cyclooctadiene) diridium, Ir2Cl2(1,5-COD)2 and its adduct with C60 were studied. The values of the isomer shifts of the d8s0 configuration would give an isomer shift of about -4mm s-1. The large positive shift to the observed value around 0 - -1 mm s-1 must be attributed to a significant population of 6s orbitals which can be rationalized in terms of a hybridization of 5dz2 with 6s. The relatively large quadrupole splittings measured in IrCl(CO)(PPh3)2 and [Ir2Cl2(1.5 COD)2]2C60-2C6H6 (6.52 mm s-1 and 6.18 mm s-1 respectively) were attributed to the (dz2)2(dx2 .y2)0 electronic configuration and the small splittings in IrCl(CO)(PPh3)22-TCNE), IrCl(CO)(PPh3)22-C60)-C 6H6 and Ir2Cl2(1.5-COD)2 were explained with (dz2)1 (dx2-y2)1 triplet structure. 57 Fe Mössbauer measurements were carried out over the range 8060(ferrocene)2. Ferrocene was also measured at room temperature. The obtained Mössbauer parameters showed that there is no measurable chemical interaction between C60 and ferrocene but the slightly decreased isomer shift of decamethyl-ferrocene (compared to that of ferrocene) demonstrated that the donor character of the methyl groups can have an effect on the electronic structure of iron (through the cp rings), as well. The asymmetry of the Mössbauer lines were explained by both Goldanskii - Karyagin effect and texture of the samples. The texture was found to be dominant in decamethyl-ferrocene and the Goldanskii-Karyagin effect results in the major part of asymmetry in fullerene(ferrocene)2. Eu3C60 and RbEu2C60 were prepared and 151Eu Mössbauer spectra were recorded on these samples. It has been found that the ratio of the intensities of the Mössbauer lines belonging to the Eu2+/Eu3+ was about 2/1 in both samples. A heat treatment at 400°C in a two weeks period increased the concentration of Eu2+.

Original languageHungarian
Pages (from-to)99-108
Number of pages10
JournalMagyar Kemiai Folyoirat, Kemiai Kozlemenyek
Volume105
Issue number3
Publication statusPublished - márc. 1999

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Fullerenes
Carbon Monoxide
Isomers
Textures
Iridium
ferrocene
Electronic structure
Iron
Heat treatment

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Fullerénvegyületek Mössbauer-spektroszkópiája. / Vértes, A.

In: Magyar Kemiai Folyoirat, Kemiai Kozlemenyek, Vol. 105, No. 3, 03.1999, p. 99-108.

Research output: Article

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title = "Fuller{\'e}nvegy{\"u}letek M{\"o}ssbauer-spektroszk{\'o}pi{\'a}ja",
abstract = "We have measured the 193Ir M{\"o}ssbauer spectrum of the adduct of chlorocarbonylbis(triphenylphosphine)iridium (IrCl(CO)(PPh3)2) with buckminsterfullerene (C60) and, for comparison, remeasured the spectra of both the parent compound and its adduct with tetracyanoethylene, (TCNE). In an other series of measurements di-μ-chloro-bis (1,5-cyclooctadiene) diridium, Ir2Cl2(1,5-COD)2 and its adduct with C60 were studied. The values of the isomer shifts of the d8s0 configuration would give an isomer shift of about -4mm s-1. The large positive shift to the observed value around 0 - -1 mm s-1 must be attributed to a significant population of 6s orbitals which can be rationalized in terms of a hybridization of 5dz2 with 6s. The relatively large quadrupole splittings measured in IrCl(CO)(PPh3)2 and [Ir2Cl2(1.5 COD)2]2C60-2C6H6 (6.52 mm s-1 and 6.18 mm s-1 respectively) were attributed to the (dz2)2(dx2 .y2)0 electronic configuration and the small splittings in IrCl(CO)(PPh3)2(η2-TCNE), IrCl(CO)(PPh3)2(η2-C60)-C 6H6 and Ir2Cl2(1.5-COD)2 were explained with (dz2)1 (dx2-y2)1 triplet structure. 57 Fe M{\"o}ssbauer measurements were carried out over the range 8060(ferrocene)2. Ferrocene was also measured at room temperature. The obtained M{\"o}ssbauer parameters showed that there is no measurable chemical interaction between C60 and ferrocene but the slightly decreased isomer shift of decamethyl-ferrocene (compared to that of ferrocene) demonstrated that the donor character of the methyl groups can have an effect on the electronic structure of iron (through the cp rings), as well. The asymmetry of the M{\"o}ssbauer lines were explained by both Goldanskii - Karyagin effect and texture of the samples. The texture was found to be dominant in decamethyl-ferrocene and the Goldanskii-Karyagin effect results in the major part of asymmetry in fullerene(ferrocene)2. Eu3C60 and RbEu2C60 were prepared and 151Eu M{\"o}ssbauer spectra were recorded on these samples. It has been found that the ratio of the intensities of the M{\"o}ssbauer lines belonging to the Eu2+/Eu3+ was about 2/1 in both samples. A heat treatment at 400°C in a two weeks period increased the concentration of Eu2+.",
author = "A. V{\'e}rtes",
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AB - We have measured the 193Ir Mössbauer spectrum of the adduct of chlorocarbonylbis(triphenylphosphine)iridium (IrCl(CO)(PPh3)2) with buckminsterfullerene (C60) and, for comparison, remeasured the spectra of both the parent compound and its adduct with tetracyanoethylene, (TCNE). In an other series of measurements di-μ-chloro-bis (1,5-cyclooctadiene) diridium, Ir2Cl2(1,5-COD)2 and its adduct with C60 were studied. The values of the isomer shifts of the d8s0 configuration would give an isomer shift of about -4mm s-1. The large positive shift to the observed value around 0 - -1 mm s-1 must be attributed to a significant population of 6s orbitals which can be rationalized in terms of a hybridization of 5dz2 with 6s. The relatively large quadrupole splittings measured in IrCl(CO)(PPh3)2 and [Ir2Cl2(1.5 COD)2]2C60-2C6H6 (6.52 mm s-1 and 6.18 mm s-1 respectively) were attributed to the (dz2)2(dx2 .y2)0 electronic configuration and the small splittings in IrCl(CO)(PPh3)2(η2-TCNE), IrCl(CO)(PPh3)2(η2-C60)-C 6H6 and Ir2Cl2(1.5-COD)2 were explained with (dz2)1 (dx2-y2)1 triplet structure. 57 Fe Mössbauer measurements were carried out over the range 8060(ferrocene)2. Ferrocene was also measured at room temperature. The obtained Mössbauer parameters showed that there is no measurable chemical interaction between C60 and ferrocene but the slightly decreased isomer shift of decamethyl-ferrocene (compared to that of ferrocene) demonstrated that the donor character of the methyl groups can have an effect on the electronic structure of iron (through the cp rings), as well. The asymmetry of the Mössbauer lines were explained by both Goldanskii - Karyagin effect and texture of the samples. The texture was found to be dominant in decamethyl-ferrocene and the Goldanskii-Karyagin effect results in the major part of asymmetry in fullerene(ferrocene)2. Eu3C60 and RbEu2C60 were prepared and 151Eu Mössbauer spectra were recorded on these samples. It has been found that the ratio of the intensities of the Mössbauer lines belonging to the Eu2+/Eu3+ was about 2/1 in both samples. A heat treatment at 400°C in a two weeks period increased the concentration of Eu2+.

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