Mechanism of associative photoinduced ligand substitution in tetracarbonyl(phenanthroline)tungsten under metal-to-ligand charge-transfer excitation: subnanosecond transient spectra and solvent and wavelength dependence evidence for rapid primary processes

Photochemistry of fac‐[Re(bpy)(CO)3Cl]

“…As described later, time-resolved UV/Vis absorption spectroscopic results also indicate that the formation of 2 a is complete within 100 ps. This is in striking contrast to the photochemical ligand substitution reaction of [W(phen)(CO) 4 ] (phen=1,10-phenanthroline) with PR 3 (R=Me, Ph, and so on), which requires a few nanoseconds for completion 21. The latter proceeds by means of the associative mechanism (i.e., nuclear attack of the phosphane on the lowest 3 m LCT excited state of the complex), as shown in Equation (5), which is similar to the process used for the formation of 2 a .…”

Origin of electronic absorption spectra of MLCT-excited and one-electron reduced 2,2′-bipyridine and 1,10-phenanthroline complexes

“…1) that shows only moderate shifts of m(CO) bands to lower energies upon reduction (Table 1), indicating that the Re atom in the anionic complexes keeps its formal oxidation state I while it is exposed to a stronger electron donation from the reduced N,N ÅÀ ligand. , which exhibits a broad absorption feature in the 560-760 nm range with a resolved vibronic structure and a maximum at 604 nm, together with a strong absorption below 500 nm steadily increasing into the UV [15]. The UV-Vis spectra of the reduced complexes are compared in Figs.…”

“…Indeed, comparison of UV-Vis absorption as well as resonance Raman and IR spectra of reduced and excited states is used to assign and characterize the lowest excited state as MLCT [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. This kind of experiments helped to establish that both reduction and MLCT excitation of [ …”

“…For example, observation of dpp ÅÀ (dpp = 2,3-bis(2-pyridyl)pyrazine) UV-Vis features in the excited-state spectrum of a dinuclear complex [(bpy) 2 Ru(l-dpp)Ru(bpy) 2 ] 2+ provided an evidence that MLCT excitation is directed to the bridging ligand instead of bpy [19]. The similarities between UV-Vis spectroscopic effects of reduction and MLCT excitation are less obvious in complexes of 1,10-phenanthroline (phen) such as [Ru(phen) 3 ] 2+ [20] and [W(CO) 4 (phen)] [15]. The very notion of the analogy between excited-and reducedstate spectra is based on the assumption that the same N,N ÅÀ chromophore is present in both states.…”

Reatividade química e fotoquímica de complexos nitrosilos de rutênio do tipo [Ru(terpy)(L)NO]n+

“…Logo, a incidência de irradiação de energia correspondente a cada uma destas transições pode conduzir a diferentes reações e propriedades fotoquímicas (LINDSAY et al, 1993). A Figura 6 ilustra, de forma simplificada, o diagrama de orbitais moleculares de um complexo de rutênio (II) e suas possíveis transições eletrônicas.…”