82598-65-0Relevant articles and documents
Reactions of metalloporphyrin π radicals. 3. Solvent- and ligand-binding effects on the one-electron oxidation of 5,10,15,20-tetraphenylporphyrin d10 metal ions in nonaqueous media
Kadish,Shiue
, p. 3623 - 3630 (2008/10/08)
Stability constants for nitrogenous base addition to (TPP)MII and [(TPP)MII]+ were determined where M = Cd and Hg. Spectrophotometric methods were utilized for the determination of the five-coordinate neutral complexes (TPP)M(L) and comparisons made with earlier published values of (TPP)Zn(L) formation. For formation of (TPP)Hg(L) values of log β10 ranged from 0.25 to 4.34. Larger values were obtained for formation of (TPP)Cd(L). Positive correlations were obtained from plots of log β10 vs. the ligand pKa, indicating the complexations were dominated by σ-bond strength of the ligand. Reversible half-wave potentials of the (TPP)M(L)/[(TPP)M(L)]+ couple shifted in a cathodic or an anodic direction by -140 to +70 mV from that of (TPP)M/[(TPP)M]+ depending upon the bound ligand. Similar shifts in potential were seen upon changing from a nonbonding nonaqueous solvent to a bonding one. Values of log β10 were combined with electrochemical data to obtain stability constants (log β1+) for the complexation of [(TPP)M]+ with nitrogenous bases. Linear relationships with positive slopes were also seen for the correlation of log β1+ with pKa of the substituted pyridines. Finally, comparisons were made between the spectral properties and reactivity of each (TPP)M(L) series.
