Rhenium diimine complex mononuclear

It has been also reported that Re—R bond homolysis can be promoted by the photoexcitation of mononuclear rhenium(I) complexes with a Re—alkyl bond, /ac-[Re(CO)3(a-diimine)R] (R = alkyl ligand). This type of the reaction also proceeds via a state, which is produced by the relaxation from the MLCT excited state. In the cases of R = ethyl (Et) and benzyl (Bz), the homolysis reaction proceeds efficiently. However, the reaction efficiency is much lower in the case R = methyl (Me) because the transition from MLCT to requires extra energy (Scheme 1). Using transient absorption spectroscopy, the state was... 

All these polymers, A (39), B (40), C (41,42), D (43), showed distinctive absorption and emission due to the MLCT transition of the rhenium(I) diimine complexes. Among these rhenium-containing polymers, polymer C has the most notable emission properties, with an emission quantum yield and a lifetime ( e = 0.132, Te = 2019ns in a deaerated CH2CI2 solution) comparable to those of the corresponding mononuclear complex (0e = O.181, Te = 2200 ns) (43). 

Z)-Stilbene]Cr(CO)3 showed three optically accessible excited states. One of these excited states caused (E)-(Z) isomerization and the other resulted in a slow release of carbon monooxide. " Tetranuclear rhenium(I) tricarbonyl diimine complexes (20) with a stilbene-like bridging ligand showed efficient photoswitching properties. The accurate quantum yields of the photoisomerization of the mononuclear rhenium(I) tricarbonyl diimine complex could be determined readily by the H NMR technique in eombination with absorption spectroscopy. ... 

The last section describes rmique and high photocatal5rtic activities of the rheniiun(I) diimine carbonyl complexes, especially for CO2 reduction. The photocatalyses of mononuclear rhenium complexes, multicomponent systems, supramolecular systems with a Ru(II) complex as a photosensitizer, and a rhenium complex with periodic mesoporous organosilica as a light-harvesting system. 

The robustness of the rhenium(i) diimine alkynyl systems and rich photophysical behavior have rendered them suitable as metalloligands for the synthesis of mixed-metal complexes. It is well-known that organometallic alkynes exhibit rich coordination chemistry with Cu(i), Ag(i) and Au(i) [214-218], however, photophysical properties of these r-coordinated compounds are rare. Recent work by Yam and coworkers has shown that luminescent mixed-metal alkynyl complexes could be synthesized by the metalloligand approach using the rhenium(i) diimine alkynyl complexes as the z -ligand. Reaction of the rhenium(i) diimine alkynyl complex [Re(bpy)(CO)3C=CPh] with [M(MeCN)4]PF6 in THF at room temperature in an inert atmosphere afforded mixed-metal Re(i)-Cu(i) or -Ag(i) alkynyl complexes (Scheme 10.31) [89]. Their photophysical properties have also been studied. These luminescent mixed-metal complexes were found to emit from their MLCT[d7i(Re) —> 7i (N N)] manifolds with emission bands blue-shifted relative to their mononuclear precursors (Table 10.5). This has been attributed to the stabilization of the dTi(Re) orbital as a consequence of the weaker t-donating ability of the alkynyl unit upon coordination to the d metal centers. 

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