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Chemical and electrochemical investigations of cobalt cyanide and ruthenium ammine complexes

Citation

Lim, Hong Sup (1972) Chemical and electrochemical investigations of cobalt cyanide and ruthenium ammine complexes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/PKKN-JV68. https://resolver.caltech.edu/CaltechTHESIS:05022016-145740021

Abstract

Part I.

The stoichiometry and kinetics of the reaction between Co(CN5H3- and HgX2 (X = CN, OH) have been investigated. The products of the reaction are two new complexes, [(NC)5Co-HgX]3- and [(NC)5Co-Hg-Co(CN)5]6-, whose spectra are reported. The kinetic measurements produced a value for the forward rate constant of the reaction Co(CN)5H3- + OH- k1/k-1 Co(CN)54- +H2O, k1 = (9.7 ± 0.8) x 10-2 M-1 sec-1 at 24°C, and an equilibrium constant for the reaction K = 10-6 M-1.

Part II.

Unusually large and sharp "adsorption waves" appear in cyclic voltammograms of Co(CN)53- and several cobalt(III) pentacyano complexes at stationary mercury electrodes. The nature of the adsorbed species and the reasons for the absence of the adsorption waves in polarograms taken with a d.m.e. have been examined. The data are compatible with the adsorption, in all cases, of a coordinatively unsaturated cobalt(II) complex, Co(CN)42-, by means of a cobalt-mercury bond. When the resulting adsorbed complex is reduced, a series of subsequent chemical and electrode reactions is initiated in which three faradays of charge are consumed for each mole of adsorbed complex. The adsorption of the anionic complex strongly retards the reduction of other negatively charged complexes.

Part III.

A number of formal redox potentials for RuIII (NH3)5L + e = RuII (NH3)5L and RuIII(NH3)4L2 + e = RuII (NH3)4L2 (where L is various ligands) has been measured by cyclic voltammetry, potentiometry, and polarography and are discussed in terms of the properties of the ligands, such as π-accepting capability. Reduction of coordinated pyrazine in the complexes, Ru(NH3)5 Pz2+, cis- and trans-Ru(NH3)4Pz22+, on a mercury electrode has been observed. The behavior of this reduction in various acidity of the solution as well as the reoxidation of the reduction products are discussed.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Anson, Fred C.
Thesis Committee:
  • Unknown, Unknown
Defense Date:27 July 1971
Funders:
Funding AgencyGrant Number
CaltechUNSPECIFIED
Record Number:CaltechTHESIS:05022016-145740021
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:05022016-145740021
DOI:10.7907/PKKN-JV68
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9698
Collection:CaltechTHESIS
Deposited By: Leslie Granillo
Deposited On:03 May 2016 16:23
Last Modified:21 Dec 2019 04:17

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