Equilibrium constants for the metalation of zinc porphyrins

Journal Article · Tue Nov 01 04:00:00 EST 1977 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic50177a073· OSTI ID:5219499

Hambright, P

The equilibrium for the general equation m/sup 2 +/ + PH/sub 2/ = MP + 2H/sup +/ for reaction of divalent metal ions and free base porphyrins (PH/sub 2/) to form metalloporphyrins (MP) was studied using Zn/sup 2 +/ and tetra(2-N-methylpyridyl)porphine. Studies were conducted by equilibrating LiNO/sub 3//HNO/sub 3/, mixtures of PH/sub 2/, ZnP, HNO/sub 3/, and Zn(NO/sub 3/)/sub 2/ in the dark at 25.5/sup 0/C and ..mu.. = 1 for periods of up to 3 weeks. At constant total porphyrin concentrations, isobestic points were found in the visible region indicating that PH/sub 2/ and ZnP were the major species. The value of the equilibrium constant for the formation of ZnP by the proposed reaction was 188 +- 11 M. Some other data are presented which indicate that the less basic is the porphyrin ligand, the more stable is the corresponding metal-porphyrin complex. (BLM)

• Research Organization: Howard Univ., Washington, DC
• OSTI ID: 5219499
• Journal Information: Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 16:11; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CARBOXYLIC ACIDS
CHEMICAL REACTION KINETICS
COMPLEXES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
KINETICS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PORPHYRINS
REACTION KINETICS
ZINC COMPLEXES