Observing the Formation and the Reactivity of an Octahedral Iron(V) Nitrido Complex in Real Time

Torres-Alacan, Joel; Das, Ujjal; Filippou, Alexander C.; Vöhringer, Peter

doi:10.1002/anie.201306621

Cited by 53 publications

(40 citation statements)

References 27 publications

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“…[40][41][42][43][44][45][46][47][48] Figure 3a displays transient IR spectra of tetrabenzylazodicarboxamide in chloroform (c = 6.6 mm)i nt he 1600-1775 cm À1 range associated with the carbonyl stretch region after excitation at 350 nm. [40][41][42][43][44][45][46][47][48] Figure 3a displays transient IR spectra of tetrabenzylazodicarboxamide in chloroform (c = 6.6 mm)i nt he 1600-1775 cm À1 range associated with the carbonyl stretch region after excitation at 350 nm.…”

Section: Switchingbetweentwoormorestatesonthemolecularlevelmentioning

confidence: 99%

“…To determine the light-triggered properties of the azodicarboxamide functional group,w eh ave performed picosecond time-resolved IR absorption spectroscopy,w hich has been shown to provide ah igh temporal resolution and structural sensitivity. [40][41][42][43][44][45][46][47][48] Figure 3a displays transient IR spectra of tetrabenzylazodicarboxamide in chloroform (c = 6.6 mm)i nt he 1600-1775 cm À1 range associated with the carbonyl stretch region after excitation at 350 nm. In agreement with our DFT calculations that show that the first electronic transition with nonzero oscillator strength is expected at around 340 nm, no transient signals could be observed upon excitation at longer wavelengths.T his transition corresponds to the S 3 !…”

Section: Switchingbetweentwoormorestatesonthemolecularlevelmentioning

confidence: 99%

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Photoinduced Pedalo‐Type Motion in an Azodicarboxamide‐Based Molecular Switch

et al. 2017

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Well-defined structural changes of molecular units that can be triggered by light are crucial for the development of photoactive functional materials.Herein, we report on anovel switch that has azodicarboxamide as its photo-triggerable element. Time-resolved UV-pump/IR probe spectroscopyi n combination with quantum-chemical calculations shows that the azodicarboxamide functionality,i nc ontrast to other azobased chromophores,does not undergo trans-cis photoisomerization. Instead, ap hotoinduced pedalo-type motion occurs, which because of its volume-conserving properties enables the design of functional molecular systems with controllable motion in aconfined space.

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Section: Switchingbetweentwoormorestatesonthemolecularlevelmentioning

confidence: 99%

Section: Switchingbetweentwoormorestatesonthemolecularlevelmentioning

confidence: 99%

Photoinduced Pedalo‐Type Motion in an Azodicarboxamide‐Based Molecular Switch

et al. 2017

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“…In addition the availability of time-dependent density functional theory (TDDFT) provides a method of describing excited state dynamics at a reasonable computational cost which can assist in explaining the results obtained in ps-TRIR experiments. [16][17][18] For the systems in this investigation these calculations provide a plausible explanation for the arrested CO-loss observed in the ps-TRIR experiments and can also help in the design of systems with specific photophysical and photochemical properties.…”

Section: Introductionmentioning

confidence: 96%

Excited state evolution towards ligand loss and ligand chelation at group 6 metal carbonyl centres

et al. 2014

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The photochemistry and photophysics of three model "half-sandwich" complexes (η(6)-benzophenone)Cr(CO)3, (η(6)-styrene)Cr(CO)3, and (η(6)-allylbenzene)Cr(CO)3 were investigated using pico-second time-resolved infrared spectroscopy and time-dependent density functional theory methods. The (η(6)-benzophenone)Cr(CO)3 complex was studied using two excitation wavelengths (470 and 320 nm) while the remaining complexes were irradiated using 400 nm light. Two independent excited states were detected spectroscopically for each complex, one an unreactive excited state of metal-to-arene charge-transfer character and the other with metal-to-carbonyl charge transfer character. This second excited state leads to an arrested release of CO on the pico-second time-scale. Low-energy excitation (470 nm) of (η(6)-benzophenone)Cr(CO)3 populated only the unreactive excited state which simply relaxes to the parent complex. Higher energy irradiation (320 nm) induced CO-loss. Irradiation of (η(6)-styrene)Cr(CO)3, or (η(6)-allylbenzene)Cr(CO)3 at 400 nm provided evidence for the simultaneous population of both the reactive and unreactive excited states. The efficiency at which the unreactive excited state is populated depends on the degree of conjugation of the substituent with the arene π-system and this affects the efficiency of the CO-loss process. The quantum yield of CO-loss is 0.50 for (η(6)-allylbenzene)Cr(CO)3 and 0.43 for (η(6)-styrene)Cr(CO)3. These studies provide evidence for the existence of two photophysical routes to CO loss, a minor ultrafast route and an arrested mechanism involving the intermediate population of a reactive excited state. This reactive excited state either relaxes to reform the parent species or eject CO. Thus the quantum yield of the CO-loss is strongly dependent on the excitation wavelength. Time-dependent density functional theory calculations confirm that the state responsible for ultrafast CO-loss has significant metal-centred character while the reactive state responsible for the arrested CO-loss has significant metal-to-carbonyl charge-transfer character. The CO-loss product (η(6)-allylbenzene)Cr(CO)2 formed following irradiation of (η(6)-allylbenzene)Cr(CO)3 reacts further with the pendent alkenyl group to form the chelate product (η(6),η(2)-allylbenzene)Cr(CO)2.

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“…As pecific time-resolved IR spectroscopic methodf or the above-mentioned processes is step-scan FTIR spectroscopy.T his methodu ses an FTIR spectrometer with a configuration that does not move the interferometer mirror continuously but in as tepwise manner and is capable of collecting data from nanoseconds to milliseconds. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] One advantageo ft ime-resolved FTIR is that as ingle measurement can cover the whole mid-IR (or also near-IR) range. The main applicationso ft he step-scanF TIR methoda re, for example, biologically relevant systems [1,[3][4][5][10][11][12][13] such as bacteriorhodopsin, [3,4] photolabile compounds such as 2-nitrobenzyl methyl ether, [9] and transitionm etal complexes.…”

Section: Introductionmentioning

confidence: 99%

Solid‐State Step‐Scan FTIR Spectroscopy of Binuclear Copper(I) Complexes

et al. 2017

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The structure in the ground and excited electronic state of two binuclear Cu N-heterocyclic phosphine complexes that are promising for implementation in organic light-emitting diodes is investigated by a combination of the time-resolved step-scan FTIR technique and quantum chemical calculations at the DFT level of theory. In contrast to the usual application of step-scan FTIR spectroscopy in solution, the herein-presented analyses are performed in a solid phase, that is, the Cu complexes are embedded in a KBr matrix (KBr pellet). The application of solid-state time-resolved step-scan FTIR spectroscopy is of great importance for transition metal complexes, since their photophysical properties often change on moving from solid to dissolved samples. The efficient applicability of the solid-state step-scan technique in a KBr matrix is demonstrated on the chosen Cu reference systems on nano- and microsecond timescales with an excitation wavelength of 355 nm. By comparison with theoretical results, the structure of the complexes in the electronic ground and lowest-lying electronically excited state can be determined.

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Observing the Formation and the Reactivity of an Octahedral Iron(V) Nitrido Complex in Real Time

Abstract: Give me five: Time-resolved Fourier-transform IR spectroscopy is used to time-resolve the formation and the reaction dynamics of a fourfold symmetrical nitrido iron(V) complex (light blue C, red Fe, blue N) in liquid solution under physiological and technologically relevant conditions.

Cited by 53 publications

References 27 publications

Photoinduced Pedalo‐Type Motion in an Azodicarboxamide‐Based Molecular Switch

Photoinduced Pedalo‐Type Motion in an Azodicarboxamide‐Based Molecular Switch

Excited state evolution towards ligand loss and ligand chelation at group 6 metal carbonyl centres

Solid‐State Step‐Scan FTIR Spectroscopy of Binuclear Copper(I) Complexes

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