Synthetic and mechanistic aspects of a new method for ruthenium-metalation of porphyrins and Schiff-bases.
A new method is presented for metalation of a wide range of free-base, neutral, cationic, and anionic porphyrins in refluxing dimethylformamide (DMF) using an easily prepared [Ru(DMF) 6](OTf) 3 complex, and comparisons are made with the more familiar metalation procedure using Ru 3(CO) 12. Both procedures generate Ru (II)(porp)(CO)L complexes (L = solvent); use of the Ru (III)-triflate precursor gives yields comparable to, or greater than, those obtained with the carbonyl, and generates no Ru-chlorin impurities. Mechanistic studies on the meso-tetraphenylporphyrin system reveal that the DMF furnishes the CO, which in the presence of essential water reduces the metal, and metalation likely occurs via a Ru (II)-CO species. Corresponding metalation of tetradentate Schiff-bases gives trans-[Ru (III)(Schiff- base)(DMF) 2]OTf complexes in yields of approximately 50%, a limitation being the accompanying hydrolysis of the Schiff-base through the presence of trace water.
Rebouças
Júlio S
JS
Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.
Cheu
Elizabeth L S
EL
Ware
Caroline J
CJ
James
Brian R
BR
Skov
Kirsten A
KA
D009682:Magnetic Resonance Spectroscopy; D008665:Metalloporphyrins / Q000138:chemical synthesis* / Q000737:chemistry* / Q000302:isolation & purification; D012428:Ruthenium / Q000737:chemistry*; D012545:Schiff Bases / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
D008665:Metalloporphyrins; D012545:Schiff Bases; D012428:Ruthenium