88563-13-7Relevant academic research and scientific papers
Electron-transfer and ligand-addition reactions of (TPP)CrClO4 and (TPP)Cr(NO) in nonaqueous media
Kelly,Kadish
, p. 679 - 687 (2008/10/08)
The electron-transfer and ligand-addition reactions of the chromium porphyrin complexes (TPP)CrClO4 and (TPP)Cr(NO) were studied in 11 nonaqueous solvents. Studies of (TPP)CrClO4 in noncoordinating solvents reveal a counterion dependence for the first reduction and first oxidation, suggesting metal-centered reactions. Spectrophotometric and electrochemical studies of (TPP)CrClO4 in mixed-solvent systems provide clear evidence for the presence of the novel species [(TPP)Cr(L)2]+ in solution, where L = DMF, Me2SO, and pyridine, and stepwise formation constants for the addition of pyridine and Me2SO are determined. Conductometric studies combine with the mixed-solvent studies to suggest that the axial environment about the central metal determines the nature of the metal-centered reduction for (TPP)CrX. Electrochemical studies of (TPP)Cr(NO) show that nitrosylation stabilizes the divalent state by over 1.0 V, and metal-centered oxidation occurs via an EC mechanism. Studies in mixed-solvent systems provide formation constants for the addition of one coordinating base to (TPP)Cr(NO) and [(TPP)Cr(NO)]-. Solvent dependences for the various redox reactions of (TPP)CrClO4 and (TPP)Cr(NO) were correlated to solvent polarity scales and suggest that different solvent-solute interactions predominate for the two complexes.
