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Title: Communication: Direct evidence for sequential dissociation of gas-phase Fe(CO)5 via a singlet pathway upon excitation at 266 nm

Authors:
ORCiD logo [1];  [1]; ORCiD logo [2];  [3]; ORCiD logo [1];  [4]; ORCiD logo [1];  [4];  [4];  [3];  [5];  [3]; ORCiD logo [2];  [4]
  1. Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
  2. Department of Physics, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden
  3. European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
  4. Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany; Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany
  5. Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1369401
DOE Contract Number:
AC02-76SF00515
Resource Type:
Journal Article
Resource Relation:
Journal Name: The Journal of Chemical Physics; Journal Volume: 146; Journal Issue: 21
Country of Publication:
United States
Language:
English

Citation Formats

Wernet, Ph., Leitner, T., Josefsson, I., Mazza, T., Miedema, P. S., Schröder, H., Beye, M., Kunnus, K., Schreck, S., Radcliffe, P., Düsterer, S., Meyer, M., Odelius, M., and Föhlisch, A. Communication: Direct evidence for sequential dissociation of gas-phase Fe(CO)5 via a singlet pathway upon excitation at 266 nm. United States: N. p., 2017. Web. doi:10.1063/1.4984774.
Wernet, Ph., Leitner, T., Josefsson, I., Mazza, T., Miedema, P. S., Schröder, H., Beye, M., Kunnus, K., Schreck, S., Radcliffe, P., Düsterer, S., Meyer, M., Odelius, M., & Föhlisch, A. Communication: Direct evidence for sequential dissociation of gas-phase Fe(CO)5 via a singlet pathway upon excitation at 266 nm. United States. doi:10.1063/1.4984774.
Wernet, Ph., Leitner, T., Josefsson, I., Mazza, T., Miedema, P. S., Schröder, H., Beye, M., Kunnus, K., Schreck, S., Radcliffe, P., Düsterer, S., Meyer, M., Odelius, M., and Föhlisch, A. Fri . "Communication: Direct evidence for sequential dissociation of gas-phase Fe(CO)5 via a singlet pathway upon excitation at 266 nm". United States. doi:10.1063/1.4984774.
@article{osti_1369401,
title = {Communication: Direct evidence for sequential dissociation of gas-phase Fe(CO)5 via a singlet pathway upon excitation at 266 nm},
author = {Wernet, Ph. and Leitner, T. and Josefsson, I. and Mazza, T. and Miedema, P. S. and Schröder, H. and Beye, M. and Kunnus, K. and Schreck, S. and Radcliffe, P. and Düsterer, S. and Meyer, M. and Odelius, M. and Föhlisch, A.},
abstractNote = {},
doi = {10.1063/1.4984774},
journal = {The Journal of Chemical Physics},
number = 21,
volume = 146,
place = {United States},
year = {Fri Jun 02 00:00:00 EDT 2017},
month = {Fri Jun 02 00:00:00 EDT 2017}
}
  • The quantitative photochemistry of ({eta}{sup 5}-C{sub 5}H{sub 5})Fe(CO){sub 2}I in room-temperature solution involving the heterolytic cleavage of iodide to form ({eta}{sup 5}-C{sub 5}H{sub 5})Fe(CO){sub 2}({eta}{sup 1}-N-pyrrolyl) has been investigated following irradiation at several wavelengths in the 488--647 nm region. The most effective photoconversions were found to take place with excitation at long wavelengths (580--647 nm) into weak low-lying absorption bands; the absolute quantum efficiency for the photoreaction of ({eta}{sup 5}-C{sub 5}H{sub 5})Fe(CO){sub 2}I in room-temperature toluene has been determined to be 0.38 ({+-} 0.02) upon Kr{sup +} laser photolysis at 647 nm. The photochemical results are in accordance with recentmore » assignments for the HOMO orbitals in ({eta}{sup 5}-C{sub 5}H{sub 5})Fe(CO){sub 2}I and demonstrate that long-wavelength irradiation provides a valuable way of effecting heterolytic Fe-I dissociation, facilitating a synthetic pathway to azaferrocene.« less
  • Gas-phase photodissociation of metal carbonyls to metal atoms and CO is well-known. Multiphoton ionization experiments have shown that dissociation of the carbonyls to ground- and excited-state metal atoms is unexpectedly efficient relative to competing ionization processes. Because the mechanisms behind metal atom formation are not entirely clear, they have investigated the KrF* laser (248 nm) multiple-photon dissociation of Cr(CO)/sub 6/ to Cr* and CO in the gas phase. They present evidence that Cr* is formed by two processes: (1) a direct process, where Cr(CO)/sub 6/ is excited into a dissociative continuum, and (2) a sequential process, where a Cr(CO)/sub 4/more » intermediate photoproduct absorbs an additional photon to produce Cr*. They monitored formation of Cr* by detecting the emission obtained upon unfocused KrF* laser irradiation of approx. 20 mtorr of Cr(CO)/sub 6/ contained in a flow cell. Laser fluences ranged from 3 to 40 mJ cm/sup -2/. Emission normal to the laser beam was dispersed by a monochromator (resolution 0.5-2 A) and detected by a photomultiplier tube in conjunction with a boxcar integrator. Standard lamps were used to calibrate the optical system.« less
  • The proton affinity (PA) and site of protonation of ((C/sub 5/H/sub 5/)(CO)Fe)/sub 2/(/mu/-CO)(/mu/-C/double bond/CH/sub 2/) (2), as well as the decomposition processes for ((C/sub 5/H/sub 5/)(CO)Fe/sub 2/(/mu/-CO)(/mu/-C/double bond/CH/sub 2/)H/sup +/ (7), are studied in the gas phase by using Fourier transform mass spectroscopy (FTMS). The PA of 2 is assigned as 232.5 /plus minus/ 2 kcal/mol (relative to PA(NH/sub 3/) = 204.0 kcal/mol) by using the bracketing technique. The site of protonation was determined by labeling studies to be the /beta/-carbon of the /mu/-ethenylidene group of 2 yielding 3 in accord with the known solution chemistry. The decomposition processes formore » collisionally activated 3 were studied in detail and compared with that for the non-protonated analogue ((C/sub 5/H/sub 5/)(CO)Fe)/sub 2/(/mu/-CO)(/mu/-C/double bond/CH/sub 2/)/sup +/. 3 decomposes by initial elimination of the three carbonyls followed by sequential C/sub 2/H/sub 2/ and H/sub 2/ eliminations yielding respectively ((C/sub 5/H/sub 5/)Fe)/sub 2/H/sup +/ and Fe/sub 2/C/sub 10/H/sub 9//sup +/. Hydrogen migration in the above fragment ions was investigated by monitoring H/D exchange with D/sub 2/ and ethene-d/sub 4/. No exchange occurs for any of the ions ((C/sub 5/H/sub 5/)(CO)Fe)/sub 2/(/mu/-CO)(/mu/-C/double bond/CH/sub 2/)H/sup +/ through ((CC/sub 5/H/sub 5/)Fe)/sub 2/H/sup +/) with D/sub 2/. With ethene-d/sub 4/, one H/D exchange is observed with ((C/sub 5/H/sub 5/)Fe)/sub 2/H/sup +/, with no exchange for any of the larger fragment ions.« less
  • Kinetic, spectroscopic, and structural analysis tested the hypothesis that a chain of residues connecting the 4{prime}-aminopyrimidine N1{prime} atoms of thiamin diphosphates (ThDPs) in the two active centers of the Escherichia coli pyruvate dehydrogenase complex E1 component provides a signal transduction pathway. Substitution of the three acidic residues (Glu{sup 571}, Glu{sup 235}, and Glu{sup 237}) and Arg{sup 606} resulted in impaired binding of the second ThDP, once the first active center was filled, suggesting a pathway for communication between the two ThDPs. (1) Steady-state kinetic and fluorescence quenching studies revealed that upon E571A, E235A, E237A, and R606A substitutions, ThDP binding inmore » the second active center was affected. (2) Analysis of the kinetics of thiazolium C2 hydrogen/deuterium exchange of enzyme-bound ThDP suggests half-of-the-sites reactivity for the E1 component, with fast (activated site) and slow exchanging sites (dormant site). The E235A and E571A variants gave no evidence for the slow exchanging site, indicating that only one of two active sites is filled with ThDP. (3) Titration of the E235A and E237A variants with methyl acetylphosphonate monitored by circular dichroism suggested that only half of the active sites were filled with a covalent predecarboxylation intermediate analog. (4) Crystal structures of E235A and E571A in complex with ThDP revealed the structural basis for the spectroscopic and kinetic observations and showed that either substitution affects cofactor binding, despite the fact that Glu{sup 235} makes no direct contact with the cofactor. The role of the conserved Glu{sup 571} residue in both catalysis and cofactor orientation is revealed by the combined results for the first time.« less
  • The results of the studies of the reactions of the transition metal carbenes demonstrate that: (1) The reactions of CpFe(CO)/sub 2/(CH/sub 2/)/sup +/ in the gas phase, specifically methylene transfer to cyclohexene, hydride abstraction to yield CpFe(CO)/sub 2/H/sub 3/, and addition of n-donor bases to the metylene carbon, are entirely in accord with the postulated solution reactions of this species and consistent with its formulation as a metal carbene. (2) The novel complex CpFe (CO)(CH/sub 2/)/sup +/ does not exhibit the carbene chemistry of the dicarbonyl species. Reaction of both cyclohexene and n-donor bases results in displacement of CH/sub 2/COmore » from the metal center, strongly suggesting the formulation of this species as a metal ketene complex. The question arises as to whether ketene is present as a structural moiety in the complex CpFe(CO)(CH/sub 2/) or whether it is formed in the intermediate which results from binding a ..pi..- or n-donor base to the coordinately unsaturated metal center. 17 references.« less