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Ultrafast Photochemistry of the [Cr(NCS)6]3- Complex in Dimethyl Sulfoxide and Dimethylformamide upon Excitation into Ligand-Field Electronic State

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Yksityiskohdat

AlkuperäiskieliEnglanti
Sivut3724-3733
Sivumäärä10
JulkaisuJournal of Physical Chemistry B
Vuosikerta124
Numero18
DOI - pysyväislinkit
TilaJulkaistu - 2020
OKM-julkaisutyyppiA1 Alkuperäisartikkeli

Tiivistelmä

The ultrafast photochemistry of the [Cr(NCS)6]3- complex upon excitation to the 4T2 ligand-field (LF) state was studied in dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) in a wide temporal range (100 fs to 9 ms) by a combination of femtosecond and nanosecond transient absorption spectroscopy techniques and supported by quantum-chemical DFT/TD-DFT calculations. The initially excited 4T2 state undergoes intersystem crossing to the vibrationally hot 2E state with time constants of 1.1 ± 0.2 and 1.8 ± 0.1 ps in DMSO and DMF, respectively. Vibrational relaxation occurs in the same time scale and takes 1-5 ps. A major part of the [Cr(NCS)6]3- complex in the 2E state undergoes intersystem crossing to the ground state with time constants of 65 ± 5 and 85 ± 5 ns in DMSO and DMF, respectively. A minor part of electronically excited [Cr(NCS)6]3- undergoes irreversible photochemical decomposition. In DMSO, the photolysis of the [Cr(NCS)6]3- complex results in single or double isothiocyanate ion release followed by the coordination of the solvent molecules with a time constant of 1 ± 0.2 ms.

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