Degree Name
Master of Science (MS)
Semester of Degree Completion
1986
Thesis Director
Edward O. Sherman
Thesis Committee Member
Richard L. Keiter
Abstract
The electrochemical oxidation of (OC)5MP-PM'(CO)5 (M=Cr, Mo, W; M'=Cr, Mo, W; M=M' or M≠M'; P-P=Ph2PCH2CH2PPh2) and the reduction of the oxidized products in a 0.1 M tetrabutyl-ammonium perchlorate methylene chloride solution at a platinum disc working electrode with a Ag/AgCl reference electrode have been studied. The number of electrons in the oxidation step was determined by comparison with the one electron oxidation of ferrocene which had a peak potential at +0.15 V.
The cyclic voltammograms of the homobimetallic and heterobimetallic complexes display two general chacteristics: quasi-reversible or irreversible one electron oxidation of each individual metal center. The chromium-chromium complex exhibits two oxidation peaks with peak potentials at +1.04 V and +1.35 V. The first oxidation peak coupled with a cathodic peak exhibits quasi-reversible behavior while the second oxidation peak exhibits irreversible behavior. The molybdenum and tungsten homobimetallic species each possess an irreversible oxidation peak at 1.06 V and 1.12 V, respectively. The heterobimetallics all exhibit irreversible behavior. The voltammograms have a single oxidation peak without a coupled cathodic peak. The anodic peak potentials occur at +0.94, +0.96, and +1.05 volts for the chromium-molybdeum, chromium-tungsten, and molybdenum-tungsten complex, respectively.
Cyclic voltammograms were also obtained for (OC)4W(Ph2P)2W(CO)4 (III) and HPh2P(OC)3W(Ph2P)2W(CO)3PPh2H (IV). The first oxidation step was coupled to a cathodic peak for each of the phosphido-bridged complexes. The peak to peak separations and peak ratios exhibit reversible behavior. The anodic peak potential for (III), corresponding to a two electron change, occurs at +0.75 V.
For complex (IV) the anodic peak potential, corresponding to a one electron change, was found at +0.19 V.
Complexes (III) and (IV) undergo second oxidation steps which are irreversible as shown by the absence of a cathodic peak. For complex (III), the second anodic peak potential was found at +1.02 V with a peak height equal to two electrons.
Complex (IV) loses a second electron at +0.72 V and a third electron at +1.4 V, accompanied by formation of metal-metal bonds of bond order 2 and 2 1/2, respectively.
Recommended Citation
Cooper, Dwayne Edward, "Electrochemical Studies of Transition Metal Carbonyls" (1986). Masters Theses. 2637.
https://thekeep.eiu.edu/theses/2637
