Investigation of the electrochemical reactivity and axial ligand binding reactions of tetraphenylporphyrin carbonyl complexes of ruthenium(II)

Article abstract of DOI:10.1021/ic00140a008

Stability constants for nitrogenous base addition to (TPP)Ru(CO) and [(TPP)Ru(CO)]⁺ were calculated. Spectrophotometric methods were utilized for stability constant determinations of the five-coordinate neutral complex while a combination of spectrophotometric and electrochemical techniques was utilized to calculate values for ligand addition to the cation radical. Twenty different nitrogenous bases were investigated. For (TPP)Ru(CO)(L) values of log β₁ ranged from 3.62 to 5.63 and generally increased as a function of the ligand pK_a. Values of log β₁ for formation of [(TPP)Ru(CO)(L)]⁺ ranged from 2.40 to 6.63 and also increased with the ligand pK_a. Comparisons were made between the measured values of log β₁ and reversible potentials for the electrode reaction (TPP)Ru(CO)(L) ? [(TPP)Ru(CO)(L)]⁺.