Document Type



Master of Science (MS)



First Advisor's Name

John T. Landrum

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Jeffrey Joens

Third Advisor's Name

Ramon Lopez de la Vega


Porphyrins, Ligand binding (Biochemistry)

Date of Defense



Phosphines and phosphites have been investigated as ligands to tetraphenylporphinato iron(II) (FeTPP) by spectrophotometric titration in tetrahydrofuran. A least squares method for determination of the equilibrium constants K1 and K2 (K1 and K2 correspond to the sequential binding constants for the formation of FeTPPL and FeTPPL2, respectively) was developed. This method eliminates the errors associated with fundamental assumptions intrinsic to the more conventional Hill plot. The visible spectrum of the 5-coordinate complex, FeTPPL, was also determined for each ligand. The equilibrium constants obtained are: {L(logK1, logK 2)}, PMe3 (5.53, 4.60); PEt3 (5.61, 4.30); P(n- Bu)3 (6.13, 5.02); P(OEt)3 (3.87, 2.82); P(O-i-Pr)3 (3.28, 1.13). The equilibrium constants are dependent upon steric bulk, σ-basicity and π-acidity.




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