Step Complex Formation in the Dichloro(5,10,15,20-tetraphenylporphinate)hafnium(IV)—Pyridine—Toluene System

Abstract

The thermodynamic characteristics and kinetics of step reactions between dichloro(5,10,15,20-tetraphenylporphinate)hafnium(IV) (Cl)2HfTPP and a “small” organic base, pyridine (Py), in toluene were studied. The coordination of the Py molecule (K1 = 1.50 × 104 l/mol) was determined. The slow irreversible displacement of Cl− in (Cl)2(Py)HfTPP into the second coordination sphere (k1 = 9.74 × 10si−4 s−1), the substitution of the second Py molecule for Cl− in (Cl)2(Py)HfTPP (K2 = 14.15 l/mol), subsequent irreversible displacement of the second Cl− ion into the outer sphere (k2 = 6.05 × 10−4 s−1), and the coordination of the third Py molecule as a result of the replacement of Cl− with the formation of [(Py)3HfTPP]2+ 2Cl− (K3 = 0.23 l/mol) at the first, second, and third stages, respectively, were observed. Prospects for the use of the metalloporphyrin as a receptor of organic N-bases were considered.