Infrared spectrum of matrix-isolated Fe(CO)5 in the FeC stretching region

Brown, J. D.; Tevault, David E.; Cormier, Alan D.; Nakamoto, Kazuo

doi:10.1016/0584-8539(75)80120-6

Cited by 6 publications

(5 citation statements)

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“…In systems such as ours, the ambient oxidizing environment gives rise to the oxidation of the active Fe fragments to form nanoclusters consisting mainly of Fe 2 O 3 . This can be summarized as follows: The kinetics of cluster formation are determined by following the symmetric and asymmetric CO stretching bands of Fe(CO) 5 at 1996 and 2019 cm -1 , respectively, the CO stretching bands of Fe 3 (CO) 12 (the most dominant intermediate) at 2046 cm -1 , and Fe−O stretch of iron oxide at 520 cm -1 . − Monitoring can also be done by following the stretching and bending of the Fe−CO equatorial ligands using the 641 cm -1 absorption band, − but this one has a weak absorbance and gives the exact same result.…”

Section: Resultsmentioning

confidence: 99%

“…Fe "active" fragments or "metallomers" . [51][52][53] Monitoring can also be done by following the stretching and bending of the Fe-CO equatorial ligands using the 641 cm -1 absorption band, [54][55][56][57] but this one has a weak absorbance and gives the exact same result. As shown in Figure 4, the Fe(CO) 5 infrared absorbance peak clearly decays, as expected, with decomposition time.…”

Section: Nfe(co)mentioning

confidence: 99%

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Nanocluster Nucleation and Growth in Polymeric Media Below the Glass Transition

2008

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The synthesis of metal nanoclusters in a polymeric environment has been shown to yield nearly monodisperse particles, whose size is controlled by the strength of the polymer/metal interactions. Although the phenomenon is quite general, little is known regarding the mechanism by which the polymer controls nanocluster size. Previous studies of the kinetics of nanocluster growth in polymeric melts above the glass transition temperature (T g) suggest that the nanoparticle size is set by the critical cluster size (nucleation stage) rather than the rate of metal precursor transport, namely, growth. In this paper, we examine the kinetics of iron oxide (Fe2O3) nanocluster formation below the glass temperature (T g) in two polymer melts: polystyrene (PS) and poly(methyl methacrylate) (PMMA). We find that the morphology of the nanoclusters formed below T g is highly sensitive to the system temperature and differs significantly from the morphology above T g. However, the kinetics of cluster formation is exponential with time in both PS and PMMA, both above and below T g. The glass transition does not significantly affect the rate constant in PS, thereby suggesting that the cluster formation mechanism is largely insensitive to the polymer state (glassy or melt). However, we find a significant difference in in the kinetics of PMMA above (where the rate constant increases exponentially with T) and below (where it is nearly constant) the T g.

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Section: Resultsmentioning

confidence: 99%

Section: Nfe(co)mentioning

confidence: 99%

Nanocluster Nucleation and Growth in Polymeric Media Below the Glass Transition

2008

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“…Brown et al studied the absorption spectrum of IPC in the region of Fe-C stretches (400-500 cm -1 ) in Ar and N2 matrices and they observed similarly at least 7 bands in Ar and 6 in N2 while only two bands are present in the gas phase. 55 We rationalize the features observed in matrices in terms of families of sites. Even the non-degenerate A2" band can be decomposed in several narrow bands.…”

Section: -Discussionmentioning

confidence: 77%

Vibrational dynamics of iron pentacarbonyl in cryogenic matrices

Thon

Chin

Chamma

et al. 2022

The Journal of Chemical Physics

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Iron pentacarbonyl is a textbook example of fluxionality. We trap the molecule in cryogenic matrices to study the vibrational dynamics of CO stretching modes involved in the fluxional rearrangement. The infrared spectrum in Ar and N2 is composed of about ten narrow bands in the spectral range of interest, indicating the population of various lattice sites and a lowering of the molecular symmetry in the trapping sites. The vibrational dynamics is explored by means of infrared stimulated photon echoes at the femtosecond scale. Vibrational dephasing and population relaxation times are obtained. The non-linear signals exhibit strong oscillations useful to disentangle the site composition of the absorption spectrum. The population relaxation involves at least two characteristic times. An evolution of the photon echo signals with the waiting time is observed. The behaviour of all the signals can be reproduced within a simple model that describes the population relaxation occurring in two-steps: relaxation of v=1 (population time T1 <100 ps) and return to v=0 (recovery time > 1ns). These two steps explain the evolution of the oscillations with the waiting time in the photon echo signals. These results discard fluxional rearrangement on the time scale of hundreds of ps in our samples. Dephasing times are of the same order of magnitude as T1: dephasing processes due to the matrix environment are rather inefficient. The photon echo experiments also reveal that intermolecular resonant vibrational energy transfers between guest molecules occur at the hundreds of ps timescale in concentrated samples (guest/host > 10 4 ).

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“…By default, the infrared band at 427 cm –1 must be ν 8 ( A 2 ″ ). Based on a matrix isolation study, the assignment of ν 8 and ν 13 was subsequently reversed and this has been adopted in the computational studies. − The justification was that under a specific set of conditions, the 477 cm –1 band was present as a doublet, while the 427 cm –1 band was always a singlet, suggesting that they were E and A modes, respectively. The INS shows that this is not tenable; there is insufficient intensity in an A -type mode to account for the INS band at 477 cm –1 .…”

Section: Resultsmentioning

confidence: 99%

“…The unusual symmetry has also meant that the vibrational spectroscopy of Fe(CO) 5 has been extensively investigated since the 1950s. − The most comprehensive study was carried out by Jones et al who measured the infrared spectra of the 12 C 16 O, 13 C 16 O, and 12 C 18 O isotopomers. Combined with the best Raman data available at the time, they derived a complete force field.…”

Section: Introductionmentioning

confidence: 99%

Structure and Spectroscopy of Iron Pentacarbonyl, Fe(CO)₅

Fortes

Parker

2022

J. Am. Chem. Soc.

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We have re-investigated the structure and vibrational spectroscopy of the iconic molecule iron pentacarbonyl, Fe(CO)5, in the solid state by neutron scattering methods. In addition to the known C2/c structure, we find that Fe(CO)5 undergoes a displacive ferroelastic phase transition at 105 K to a P1̅ structure. We propose that this is a result of certain intermolecular contacts becoming shorter than the sum of the van der Waals radii, resulting in an increased contribution of electrostatic repulsion to these interactions; this is manifested as a strain that breaks the symmetry of the crystal. Evaluation of the strain in a triclinic crystal required a description of the spontaneous strain in terms of a second-rank tensor, something that is feasible with high-precision powder diffraction data but practically very difficult using strain gauges on a single crystal of such low symmetry. The use of neutron vibrational spectroscopy (which is not subject to selection rules) has allowed the observation of all the fundamentals below 700 cm–1 for the first time. This has resulted in the re-assignment of several of the modes. Surprisingly, density functional theory calculations that were carried out to support the spectral assignments provided a poor description of the spectra.

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Infrared spectrum of matrix-isolated Fe(CO)5 in the FeC stretching region

Cited by 6 publications

References 5 publications

Nanocluster Nucleation and Growth in Polymeric Media Below the Glass Transition

Nanocluster Nucleation and Growth in Polymeric Media Below the Glass Transition

Vibrational dynamics of iron pentacarbonyl in cryogenic matrices

Structure and Spectroscopy of Iron Pentacarbonyl, Fe(CO)₅

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Infrared spectrum of matrix-isolated Fe(CO)5 in the FeC stretching region

Cited by 6 publications

References 5 publications

Nanocluster Nucleation and Growth in Polymeric Media Below the Glass Transition

Nanocluster Nucleation and Growth in Polymeric Media Below the Glass Transition

Vibrational dynamics of iron pentacarbonyl in cryogenic matrices

Structure and Spectroscopy of Iron Pentacarbonyl, Fe(CO)5

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Product

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Structure and Spectroscopy of Iron Pentacarbonyl, Fe(CO)₅