pH control of the photophysical properties of ruthenium complexes containing 3-(pyrazin-2-yl)-1,2,4-triazole ligands

Photochemistry of the metal-metal-bonded complexes [(CO)5MnRu(Me)(CO)2(α-diimine)]. Crystal structure of the photoproduct [(CO)4Mn-μ-(σ(N),σ(N′),ν2(CN)-iPr-PyCa)Ru(Me)(CO)2]

“…The emission lifetime of this state has recently been measured for MnRuDAB and MnRuPyCa in a 2-MeTHF glass at 77 K [19]. The lifetime of 10 /zs measured for MnRuDAB agrees with that of a few microseconds at room temperature derived from the transient absorption spectra in hexane [ Fig.…”

“…In contrast, the emission of these [(CO)hMn-Ru(MeXCO)z(a-diimine)] complexes in a 2-MeTHF glass at 77 K had a much longer lifetime and lower quantum yield than might be expected for a lowest MLCT state [19]. These long lifetimes and low quantum yields pointed to the presence of a lowest 3 o%~-* state, from which radiative transfer to the ground state is overlap-forbidden, and which has become occupied by surface crossing from the MLCT state(s).…”

“…A similar excited-state process was found for population of the D ~ a-diimine excited state of the chromophore-quencher complexes [Re(D)(CO)3(a-diimine)] + (D = electron donor) [15-171. We have recently prepared two complexes [(CO) 5-Mn-Ru(Me)(CO)2(a-diimine)] [a-diimine = pyridine-2-carbaldehyde-N-isopropylimine (ipr-PyCa) or N,N'-diisopropyl-l,4-diaza-l,3-butadiene (ipr-DAB)] (see Fig. 1) and studied their spectroscopic properties [18] and emission spectra at low temperature [19]. By the use of resonance Raman spectroscopy, the visible ab-....... co\ ./ CO---Mn Ru …”

Synthesis and spectroscopic properties of Re(R)(CO)3(α-diimine) (R  alkyl; α-diimine  R′-pyCa, R′-DAB) complexes. Crystal structure of Re(Me) (CO)3 (iPr-DAB)

“…The spectroscopic, photophysical and photochemical properties of the first set of complexes have been described elsewhere [12][13][14], while the synthesis, structural and spectroscopic properties of the second set are reported here. A preliminary account of the photochemistry of these Re complexes has appeared [15].…”

Synthesis, structure and spectroscopic properties of novel metal-metal bonded manganese-ruthenium complexes with α-diimine ligands. X-ray structure of [(CO)5MnRu(Me)(CO)2(σ(N′)-iPr-PyCa)] (iPr-PyCa = pyridine-2-carbaldehyde-N-isopropylimine)

“…The homolytic splitting of the Mn-Ru bond, observed for these complexes [31], must therefore proceed from a state, presumably 3~r~r*, which is not directly occupied by visible excitation but only indirectly via non-reactive MLCT states. Although the absorption and rR spectra clearly show that the o-b ~ ~-* transition does not contribute to the visible absorption band, the presence of a 3o'b~r* state at rather low energy has recently been established for these complexes by a weak and long lived emission in an MeTHF glass at 77 K [32]. The consequences of these absorption, rR and emission data for the photochemical behaviour of these complexes will be discussed in a forthcoming article [311.…”