Schilt, Alfred Ayars, 1927-
M.S. (Master of Science)
Department of Chemistry
Organonitrogen compounds; Organoiron compounds; Complex compounds
The acid dissociations constants of 2,4,6-tris(2-pyridyl)- 1,3,5-triazine, TPTZ, and 2,6-bis(2-pyridyl)-pyridine, terpy, were reevaluated using successive approximations to match calculated with experimental curves of absorbance vs. pH. The results are pKa₁=2.10 and pKa₂=3.40 for TPTZ, and pKa₁=3.60 and pKa₂=4.62 for terpy. The formation constants of the bis-complexes of TPTZ with iron(II) and of terpy with iron(II) were redetermined based on the above pKa's. The results are log K[sub f]=11.00 with a standard derivation of 0.04 for Fe(TPTZ)₂⁺² and log K[sub f]=21.00 with a standard derivation of 0.24 for Fe(terpy)₂⁺². For the ternary complex, Fe(TPTZ)(terpy)⁺², four different approaches were explored to determine the equilibrium constants, but only one proved successful. A value of 0.394 with a standard derivation of 0.06 was obtained for the mixing constant, K[sub M], determined photometrically by the method of continuous variations applied to mixtures of the binary complexes. The other ternary constants, K[sub f] K(+B-A)₁₁, K(+A-B)₁₁, and K[sub S], were calculated from K[sub M] and the formation constants of the binary complexes. The results indicate that formation of the mixed ligand complex involves a small loss in stabilization energy, due perhaps to some interaction between the dissimilar ligands or to a loss in solvation energy.
Wong, Sy-Wen, "Protonation and complexation constants for 2, 6-bis (2-pyridyl)-pyridine and 2, 4, 6-tris (2-pyridyl)-1,3,5-triazine and their binary and ternary complexes of iron(II )" (1983). Graduate Research Theses & Dissertations. 4570.
viii, 58 pages
Northern Illinois University
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