41697-90-9Relevant academic research and scientific papers
Spectrophotometric and resonance Raman studies on the formation of phenolate and thiolate complexes of (octaethylporphinato)iron(III)
Uno, Tadayuki,Hatano, Keiichiro,Nishimura, Yoshifumi,Arata, Yoji
, p. 2803 - 2807 (2008/10/08)
Reactions of (octaethylporphinato)iron(III) methoxide, Fe(OEP)(OMe), with a series of phenols, carboxylic acids (ROH), and thiols (RSH) were monitored by spectrophotometric techniques. The equilibrium constants for addition of ROH to Fe(OEP)(OMe) were measured, and it was found that increased acidity of the ROH moiety caused the equilibrium constant to increase. The reaction of Fe(OEP)(OMe) with RSH proceeded significantly slowly at 20°C. The second-order rate constants were obtained and were found to increase with the increase of RSH acidity. These indicate that dissociation of a proton from an ROH or RSH moiety will promote the formation of the product species Fe(OEP)(OR) or Fe(OEP)(SR). By the use of resonance Raman spectroscopy, both product species were found to be five-coordinate ferric high-spin complexes. The Fe(OEP)(OPh) complex showed the ν(Fe-OPh) stretching Raman line at 607 cm-1. The visible absorption maxima of the porphyrin π to iron dπ transitions (CT band) of Fe(OEP)(OR) and Fe(OEP)(SR) were a linear function of the pKa of ROH and RSH, and the hypsochromic shift with the increasing pKa was explained in terms of the electron-donating ability of the OR and SR ligands. The absorption maxima of Fe(OEP)(SR) were generally shifted to longer wavelength than those of Fe(OEP)(OR).
