Unimolecular Double Photoionization-Induced Processes in Iron Pentacarbonyl.
Ontology highlight
ABSTRACT:
SUBMITTER: Linguerri R
PROVIDER: S-EPMC8653154 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Iron pentacarbonyl (Fe(CO)5) is a versatile material that is utilized as an inhibitor of flame, shows soot suppressibility, and is used as a precursor for focused electron-beam-induced deposition (FEBID). X-ray absorption near-edge structure (XANES) of the K edge, which is a powerful technique for monitoring the oxidation states and coordination environment of metal sites, can be used to gain insight into Fe(CO)5-related reaction mechanisms in in situ experiments. We use a finite difference method (FDM) and molecular-orbital-based time-dependent density functional theory (TDDFT) calculations to clarify the Fe K-edge XANES features of Fe(CO)5. The two pre-edge peaks P1 and P2 are mainly the Fe(1s) ? Fe-C(?*) and Fe(1s) ? Fe-C(?*) transitions, respectively. When the geometry transformed from D 3h to C 4v symmetry, a ?30% decrease of the pre-edge P2 intensity was observed in the simulated spectra. This implies that the ? bonding of Fe and CO is sensitive to changes in geometry. The following rising edge and white line regions are assigned to the Fe(1s) ? Fe(4p)(mixing C(2p)) transitions. Our results may provide useful information to interpret XANES spectra variations of in situ reactions of metal-CO or similar compounds with ? acceptor ligandlike metal-CN complexes.
| S-EPMC7081404 | biostudies-literature
Project description:The open-shell iron pentacarbonyl cation [Fe(CO)5 ].+ was isolated by deelectronation, i.e., the single-electron oxidation of the parent neutral Fe(CO)5 using [phenazineF ].+ as the [Al(ORF )4 ]- and [F-{Al(ORF )3 }2 ]- salt (RF =C(CF3 )3 ; phenazineF =perfluoro-5,10-bis(perfluorophenyl)-5,10-dihydrophenazine). [Fe(CO)5 ].+ [Al(ORF )4 ]- was fully characterized (scXRD analysis, IR, NMR, EPR, 57 Fe spectroscopy, CV and SQUID magnetization study) and, apart from being a compound of fundamental interest, may serve as a precursor for low-valent iron coordination chemistry.
| S-EPMC9401057 | biostudies-literature
Project description: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.
| S-EPMC9523711 | biostudies-literature
Project description:We present the phase diagram of Fe(CO)5, consisting of three molecular polymorphs (phase I, II and III) and an extended polymeric phase that can be recovered at ambient condition. The phase diagram indicates a limited stability of Fe(CO)5 within a pressure-temperature dome formed below the liquid- phase II- polymer triple point at 4.2 GPa and 580 K. The limited stability, in turn, signifies the temperature-induced weakening of Fe-CO back bonds, which eventually leads to the dissociation of Fe-CO at the onset of the polymerization of CO. The recovered polymer is a composite of novel nm-lamellar layers of crystalline hematite Fe2O3 and amorphous carbon-oxygen polymers. These results, therefore, demonstrate the synthesis of carbon-oxygen polymer by compressing Fe(CO)5, which advocates a novel synthetic route to develop atomistic composite materials by compressing organometallic compounds.
| S-EPMC4601022 | biostudies-literature
Project description:Inferences we make about underlying cognitive processes can be jeopardized in two ways due to problematic forms of aggregation. First, averaging across individuals is typically considered a very useful tool for removing random variability. The threat is that averaging across subjects leads to averaging across different cognitive strategies, thus harming our inferences. The second threat comes from the construction of inadequate research designs possessing a low diagnostic accuracy of cognitive processes. For that reason we introduced the systems factorial technology (SFT), which has primarily been designed to make inferences about underlying processing order (serial, parallel, coactive), stopping rule (terminating, exhaustive), and process dependency. SFT proposes that the minimal research design complexity to learn about n number of cognitive processes should be equal to 2 (n) . In addition, SFT proposes that (a) each cognitive process should be controlled by a separate experimental factor, and (b) The saliency levels of all factors should be combined in a full factorial design. In the current study, the author cross combined the levels of jeopardies in a 2 × 2 analysis, leading to four different analysis conditions. The results indicate a decline in the diagnostic accuracy of inferences made about cognitive processes due to the presence of each jeopardy in isolation and when combined. The results warrant the development of more individual subject analyses and the utilization of full-factorial (SFT) experimental designs.
| S-EPMC4204447 | biostudies-literature
Project description:When small quantum systems, atoms or molecules, absorb a high-energy photon, electrons are emitted with a well-defined energy and a highly symmetric angular distribution, ruled by energy quantization and parity conservation. These rules are based on approximations and symmetries which may break down when atoms are exposed to ultrashort and intense optical pulses. This raises the question of their universality for the simplest case of the photoelectric effect. Here we investigate photoionization of helium by a sequence of attosecond pulses in the presence of a weak infrared laser field. We continuously control the energy of the photoelectrons and introduce an asymmetry in their emission direction, at variance with the idealized rules mentioned above. This control, made possible by the extreme temporal confinement of the light-matter interaction, opens a road in attosecond science, namely, the manipulation of ultrafast processes with a tailored sequence of attosecond pulses.
| S-EPMC7245115 | biostudies-literature
Project description:BACKGROUND:Lung cancer is the most common adult malignancy accounting for the largest proportion of cancer related deaths. Iron (Fe) is an essential trace element and is a component of several major metabolic pathways playing an important role in many physiological processes. In this study we evaluated the association between Fe concentration in serum, iron metabolism parameters and genetic variaton in 7 genes involved in iron metabolism and anti-oxidative processes with the incidence of lung cancer in Poland. MATERIALS AND METHODS:The study included 200 lung cancer patients and 200 matched healthy control subjects. We analyzed serum iron concentration and iron metabolism parameters (TIBC, UIBC, serum ferritin and transferrin saturation), and genotyped seven variants in seven genes: HFE, TFR1, HAMP, TF, SOD2, CAT and GPX1. RESULTS:Lung cancer patients compared to their matched controls had significantly higher mean serum iron level (p = 0.01), ferritin level (p = 0.007) and TIBC (p = 0.006). Analysis revealed that higher concentration of iron and ferritin (IVth quartile) compared to the lower concentration (Ist quartile) was associated with over 2-fold increased lung cancer incidence. We also found that higher transferrin saturation (p = 0.01) and lower TIBC (p<0.01) are associated with better survival of lung cancer patients. The analysis of polymorphisms in iron related genes did not reveal a significant difference between lung cancer patients and controls. However, rs10421768 in HAMP showed a borderline statistically significant correlation with lung cancer risk (OR = 2.83, p = 0.05). CONCLUSIONS:The results of this case control study indicate that higher body iron represented by higher Fe and ferritin levels may be associated with lung cancer incidence. Rs10421768 in HAMP may be associated with about 3-times higher lung cancer risk. Higher Fe body content may be associated with better survival of lung cancer patients.
| S-EPMC6331102 | biostudies-literature
Project description:The ability to regulate oxygen consumption evolved in ancestral animals and is intrinsically linked to iron metabolism. The iron pathways have been intensively studied in mammals, whereas data on distant invertebrates are limited. Sea sponges represent the oldest animal phylum and have unique structural plasticity and capacity to reaggregate after complete dissociation. We studied iron metabolic factors and their expression during reaggregation in the White Sea cold-water sponges Halichondria panicea and Halisarca dujardini. De novo transcriptomes were assembled using RNA-Seq data, and evolutionary trends were analyzed with bioinformatic tools. Differential expression during reaggregation was studied for H. dujardini. Enzymes of the heme biosynthesis pathway and transport globins, neuroglobin (NGB) and androglobin (ADGB), were identified in sponges. The globins mutate at higher evolutionary rates than the heme synthesis enzymes. Highly conserved iron-regulatory protein 1 (IRP1) presumably interacts with the iron-responsive elements (IREs) found in mRNAs of ferritin (FTH1) and a putative transferrin receptor NAALAD2. The reaggregation process is accompanied by increased expression of IRP1, the antiapoptotic factor BCL2, the inflammation factor NF?B (p65), FTH1 and NGB, as well as by an increase in mitochondrial density. Our data indicate a complex mechanism of iron regulation in sponge structural plasticity and help to better understand general mechanisms of morphogenetic processes in multicellular species.
| S-EPMC7034838 | biostudies-literature
Project description:Fibrous erionite-Na from Rome (Oregon, USA) was K-exchanged and characterized from the structural point of view. In addition, the modifications experienced after contact with a Fe(II) source were investigated for evaluating if the large potassium ions, blocking off nearly all the erionite cavity openings, might prevent the Fe(II) binding process, which is currently assumed to be one of the reasons of the toxicity of erionite. The K-exchanged sample had a 95% reduction of the BET surface area indicating that it behaves as a mesoporous material. Exchanged K is segregated at K2 and at OW sites commonly occupied by H2O. The latter K cations provide a relevant contribution to the reduction of the surface area. Surprisingly, despite the collapse of its surface area the sample preserves the tendency to bind Fe(II). Therefore, yet in the case of a peculiar and potentially hostile structural environment the Fe(II) ion-exchange process has essentially the same kinetics observed in a typical erionite sample. This is a clear evidence of the very limited effect of the chemical composition of erionite on the Fe(II) binding process and reasonably it does not play a significant role in its toxicity.
| S-EPMC5431018 | biostudies-literature
Project description:The hydrocarboxyl radical (HOCO) is an important species in combustion and astrochemistry because it is easily converted to CO2 after hydrogen reduction. In this study, the formation mechanism of the HOCO radical in a CO-H2O system was investigated by direct ab initio molecular dynamics calculations. Two reactions were examined for HOCO formation. First, the reaction dynamics of the CO-H2O cluster cation, following the ionization of the neutral parent cluster CO(H2O) n (n = 1-4), were investigated. Second, the bimolecular collision reaction between CO and (H2O) n + was studied. In the ionization of the CO(H2O) n clusters (n = 3 and 4), proton transfer, expressed as CO(H2O) n + → CO-(OH)H3O+(H2O) n -2, occurred within the (H2O) n + cluster cation, and the HOCO radical was yielded as a product upon addition of CO and OH. This reaction proceeds under zero-point energy. Also, this radical was effectively formed from the collision reaction of CO with water cluster cation (H2O) n +, expressed as CO + OH(H3O+)(H2O) n -2 → HOCO-H3O+ + (H2O) n -2. If the intermolecular vibrational stretching mode is excited in the CO(H2O) n cluster (vibrational stretching between CO and the water cluster), the HOCO radical was detected after ionization when n = 2. The reaction mechanism was discussed based on the theoretical results.
| S-EPMC8246690 | biostudies-literature