title: Photochemical ligand substitution reactions of fac-[Re(bpy)(CO)3Cl] and derivatives.
abstract: Excitation by high-energy light, such as that of 313 nm wavelength, induces a photochemical ligand substitution (PLS) reaction of fac-[Re(bpy)(CO)3Cl] (1a) to give the solvento complexes (OC-6-34)- and (OC-6-44)-[Re(bpy)(CO)2(MeCN)Cl] (2 and 3) in good yields. The disappearance quantum yield of 1a was 0.01+/-0.001 at 313 nm. The products were isolated, and X-ray crystallographic analysis was successfully performed for 2. Time-resolved IR measurements clearly indicated that the CO ligand dissociates with subpicosecond rates after excitation, leading to vibrationally hot photoproducts, which relax within 50-100 ps. Detailed studies of the reaction mechanism show that the PLS reaction of 1a does not proceed via the lowest vibrational level in the 3MLCT excited state. The PLS reaction gives 2 and (OC-6-24)-[Re(bpy)(CO)2(MeCN)Cl] (5) as primary products, and one of the products, 5, isomerizes to 3. This type of PLS reaction is more general, occurring in various fac-rhenium(I) diimine tricarbonyl complexes such as fac-[Re(X2bpy)(CO)3Cl] (X2bpy=4,4'-X2-bpy; X=MeO, NH2, CF3), fac-[Re(bpy)(CO)3(pyridine)]+, and fac-[Re(bpy)(CO)3(MeCN)]+. The stable photoproducts (OC-6-44)- and (OC-6-43)-[Re(bpy)(CO)2(MeCN)(pyridine)]+ and (OC-6-32)- and (OC-6-33)-[Re(bpy)(CO)2(MeCN)2]+ were isolated. The PLS reaction of rhenium tricarbonyl-diimine complexes is therefore applicable as a general synthetic method for novel dicarbonyls.
authors: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1, E1-9, Meguro-ku, Tokyo 152-8551, Japan.
authors: Shunsuke
authors: S
authors: Sato
authors: Akiko
authors: A
authors: Sekine
authors: Yuji
authors: Y
authors: Ohashi
authors: Osamu
authors: O
authors: Ishitani
authors: Ana Maria
authors: AM
authors: Blanco-Rodríguez
authors: Antonín
authors: A
authors: Vlcek
authors: Taiju
authors: T
authors: Unno
authors: Kazuhide
authors: K
authors: Koike
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010777:Photochemistry; D012211:Rhenium / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D008024:Ligands; D002713:Chlorine; D012211:Rhenium; D002248:Carbon Monoxide