|Name||Mr. Will Smith|
|Organization||University of Tampa|
Quantum mechanical investigation of the inner sphere reduction mechanism of the [(NSSSN)Co(III)Cl2+], [(NSNSN)Co(III)Cl3+], and their nitrogen analog [(NNNNN)Co(III)Cl4+], cations by iron(II)
Will Smith, Thomas Jackman, Olaseni Sode
University of Tampa
The inner-sphere pathway is an electron transfer mechanism that utilizes a bridging ligand to covalently link oxidant and reductant centers. The reduction of chloro-N-methyl-bis(5-amino-3-thiapentyl)amine cobalt(III) [(NSNSN)Co(III)Cl+] and chloro(1,11-diamino-3,6,9-trithiaundecane)cobalt(III) cation [(NSSSN)Co(III)Cl+] by Iron(II) via inner-sphere electron transfer have been shown experimentally to occur with similar rate constants and more than 105 times faster than the nitrogen analog (NNNNN) It has been hypothesized that this is due to non-bridging ligand effects. To test this hypothesis, the role of ground state electronic effects by the sulphur-containing ligands on the electron transfer is investigated through the use of quantum chemistry methods. The non-bridging ligand effects were investigated through the geometry and vibrational frequencies of the precursor, transition state, and successor complexes using density functional theory (DFT) and multi-configurational self-consistent field (MCSF) methods to provide molecular orbital based evidence of the results. Rate constants for the electron transfer processes were determined utilizing Marcus theory and compared against experimental values.