Date of Award
2000
Document Type
Honors Thesis (Open Access)
Department
Colby College. Chemistry Dept.
Advisor(s)
D. Whitney King
Second Advisor
Thomas Shattuck
Abstract
The complexation of metal ions in natural waters plays a critical role in defining the metal's biogeochemistry, Numerous investigators have used various experimental techniques to measure complexation constants in the laboratory, but many constants are still poorly undefined or have yet to be investigated due to the difficulty of some of the experiments. A computational approach to obtaining these constants for complexes of Fe(lII), Fe(D), Cr(lli), Cu(lI), Zn(II), and Cd(II) was explored with varying degrees of success. Calculated Gibbs Free Energies were compared to experimental stability constants. Calculations were performed using Spartan's DFT package at the pEP level and with the DN* and DN** basis sets. Convergence success was in the following order, with the most successful first: Fe(ill), Zn(II), Cd(II), Cr(III), Cu(II), Fe(ll). Calculated hydrolysis constants for Fe(IU) and Zn(TI) followed a linear trend with experimental data. Fe(III) complexation with F, cr, Br, and 6 CN' as ligands also formed a linear trend and had a slope (10.4) closer to RT (2.48) than that for Fe(l1I) hydrolysis (26.4). By accounting for the relative st.abilization by solvation of the ligands. about half of this difference was closed.
Keywords
Metal Ion, computational approach
Recommended Citation
St. Clair, Jason, "A Computational Approach to Determining Stability Constants for Transition Metal Ion Complexes" (2000). Honors Theses. Paper 480.https://digitalcommons.colby.edu/honorstheses/480
Copyright
Colby College theses are protected by copyright. They may be viewed or downloaded from this site for the purposes of research and scholarship. Reproduction or distribution for commercial purposes is prohibited without written permission of the author.