Photoaquation Mechanism of Hexacyanoferrate(II) Ions: Ultrafast 2D UV and Transient Visible and IR Spectroscopies

Reinhard, Marco; Auböck, Gerald; Besley, Nicholas A.; Clark, Ian P.; Greetham, Gregory M.; Hanson‐Heine, Magnus W. D.; Horvath, Raphael; Murphy, Thomas S.; Penfold, Thomas J.; Towrie, Michael; George, Michael W.; Chergui, Majed

doi:10.1021/jacs.7b02769

Cited by 46 publications

(40 citation statements)

References 88 publications

(210 reference statements)

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“…Herington and Kynaston 15 found this molecule to absorb at 2043 ± 10 cm −1 . Furthermore, in a very recent investigation of the ultrafast photochemistry of ferrocyanide 7 , a very similar product band near 2049 cm −1 was observed after 400 nm excitation, which was assigned to the ferrous photoaquated species. It is a known product of UV-vis irradiation of [Fe(CN) 6 ] 4− in water and it is formed after the dissociation of a cyanide ion:…”

Section: Photochemical Reactionsmentioning

confidence: 73%

“…As an example, while the ferrous species has a charge transfer to solvent (CTTS) band in the UV-VIS spectral region 2,3 , this transition is not observed for the ferric complex. Whereas the behavior of ferrocyanide under photo excitation is starting to be understood (there is a marked wavelength dependence of the branching ratio of photo aquation vs photo oxidation) [4][5][6][7] , several questions remain open regarding the photochemistry of ferricyanide. Its relaxation pathways following photo excitation of a ligand-to-metal charge transfer (LMCT) transition have not been fully determined yet.…”

Section: Introductionmentioning

confidence: 99%

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Charge-transfer and impulsive electronic-to-vibrational energy conversion in ferricyanide: ultrafast photoelectron and transient infrared studies

Ojeda

Arrell

Longetti

et al. 2017

Phys. Chem. Chem. Phys.

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The photophysics of ferricyanide in HO, DO and ethylene glycol was studied upon excitation of ligand-to-metal charge transfer (LMCT) transitions by combining ultrafast photoelectron spectroscopy (PES) of liquids and transient vibrational spectroscopy. Upon 400 nm excitation in water, the PES results show a prompt reduction of the Fe to Fe and a back electron transfer in ∼0.5 ps concomitant with the appearance and decay of a strongly broadened infrared absorption at ∼2065 cm. In ethylene glycol, the same IR absorption band decays in ∼1 ps, implying a strong dependence of the back electron transfer on the solvent. Thereafter, the ground state ferric species is left vibrationally hot with significant excitation of up to two quanta of the CN-stretch modes, which completely decay on a 10 ps time scale. Under 265 nm excitation even higher CN-stretch levels are populated. Finally, from a tiny residual transient IR signal, we deduce that less than 2% of the excited species undergo photoaquation, in line with early flash photolysis experiments. The latter is more significant at 265 nm compared to 400 nm excitation, which suggests photodissociation in this system is an unlikely statistical process related to the large excess of vibrational energy.

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Section: Photochemical Reactionsmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Charge-transfer and impulsive electronic-to-vibrational energy conversion in ferricyanide: ultrafast photoelectron and transient infrared studies

Ojeda

Arrell

Longetti

et al. 2017

Phys. Chem. Chem. Phys.

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“…In this respect, CTTS states are ideal objects to investigate the process of purely electronic solvation dynamics. CTTS states are not limited to atomic ions, but also occur in molecules, and the case of aqueous ferrous cyanide [Fe(CN) 6 ] 4+ is the most famous example, with its CTTS states lying in the 260–295 nm range and therefore, easily accessible 236 . Here, we focus on the studies of aqueous iodide and ferrous hexacyanide by the Chergui group.…”

Section: Charge Transfer To Solventmentioning

confidence: 99%

Charge migration and charge transfer in molecular systems

Wörner

Arrell

Banerji

et al. 2017

Structural Dynamics

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181

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The transfer of charge at the molecular level plays a fundamental role in many areas of chemistry, physics, biology and materials science. Today, more than 60 years after the seminal work of R. A. Marcus, charge transfer is still a very active field of research. An important recent impetus comes from the ability to resolve ever faster temporal events, down to the attosecond time scale. Such a high temporal resolution now offers the possibility to unravel the most elementary quantum dynamics of both electrons and nuclei that participate in the complex process of charge transfer. This review covers recent research that addresses the following questions. Can we reconstruct the migration of charge across a molecule on the atomic length and electronic time scales? Can we use strong laser fields to control charge migration? Can we temporally resolve and understand intramolecular charge transfer in dissociative ionization of small molecules, in transition-metal complexes and in conjugated polymers? Can we tailor molecular systems towards specific charge-transfer processes? What are the time scales of the elementary steps of charge transfer in liquids and nanoparticles? Important new insights into each of these topics, obtained from state-of-the-art ultrafast spectroscopy and/or theoretical methods, are summarized in this review.

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“…The aim of this work was to envisage direct NCMe coordination on the 3 considered to be involved in such mechanisms via intersystem crossing (ISC) through a neighboring minimum energy crossing point (MECP), allowing the system to populate an electrophilic, coordinatively unsaturated, and closed-shell species. The final coordination of a molecule of incoming ligand is thought to be an efficient process [43][44][45][46][47] and yields a κ 1 -bound intermediate product that requires the absorption of a second photon to fully release the departing bidentate ligand [48,49]. However an alternative pathway can also be envisaged, overall requiring only one photon, namely the direct reaction between the incoming ligand and the complex in its distorted 3 MC state, to form a new complex with triplet spin multiplicity according to Wigner rules.…”

Section: Resultsmentioning

confidence: 99%

On the Possible Coordination on a 3MC State Itself? Mechanistic Investigation Using DFT-Based Methods

et al. 2020

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Understanding light-induced ligand exchange processes is key to the design of efficient light-releasing prodrugs or photochemically driven functional molecules. Previous mechanistic investigations had highlighted the pivotal role of metal-centered (MC) excited states in the initial ligand loss step. The question remains whether they are equally important in the subsequent ligand capture step. This article reports the mechanistic study of direct acetonitrile coordination onto a 3MC state of [Ru(bpy)3]2+, leading to [Ru(bpy)2(κ1-bpy)(NCMe)]2+ in a 3MLCT (metal-to-ligand charge transfer) state. Coordination of MeCN is indeed accompanied by the decoordination of one pyridine ring of a bpy ligand. As estimated from Nudged Elastic Band calculations, the energy barrier along the minimum energy path is 20 kcal/mol. Interestingly, the orbital analysis conducted along the reaction path has shown that creation of the metallic vacancy can be achieved by reverting the energetic ordering of key dσ* and bpy-based π* orbitals, resulting in the change of electronic configuration from 3MC to 3MLCT. The approach of the NCMe lone pair contributes to destabilizing the dσ* orbital by electrostatic repulsion.

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Photoaquation Mechanism of Hexacyanoferrate(II) Ions: Ultrafast 2D UV and Transient Visible and IR Spectroscopies

Cited by 46 publications

References 88 publications

Charge-transfer and impulsive electronic-to-vibrational energy conversion in ferricyanide: ultrafast photoelectron and transient infrared studies

Charge-transfer and impulsive electronic-to-vibrational energy conversion in ferricyanide: ultrafast photoelectron and transient infrared studies

Charge migration and charge transfer in molecular systems

On the Possible Coordination on a 3MC State Itself? Mechanistic Investigation Using DFT-Based Methods

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