Syntheses and Electrochemistry of Monosubstituted Carbonyl Complexes of Low Valent Ruthenium

Author

Nor Azowa Ibrahim, Eastern Illinois University

Degree Name

Master of Science (MS)

Semester of Degree Completion

1986

Thesis Director

Richard L. Keiter

Abstract

The reactions of Ph₂MeP and PhMe₂P with (PPh₃)₄RuCl₂ yield (PPh₂Me)₄RuCl₂ and (PPhMe₂)₄RuCl₂, respectively. These complexes have been shown by conductivity studies to be dissociated in acetonitrile and exist as [(PPh₂Me)₄RuCl(CH₃CN)]Cl and [(PPhMe₂)₄RuCl(CH₃CN)]Cl. When carbon monoxide was bubbled into these solutions, monocarbonyl complexes were obtained. Elemental analyses, ¹H NMR, ³¹P NMR, infrared spectroscopy, conductivity measurements, and polarography were used to analyse the products, (PPh₂Me)₂RuCO(CH₃CN)Cl₂ and (PPhMe₂)₃RuCOCl₂. The structures of the complexes were elucidated and in each case two phosphine ligands were trans and two chloride ligands were cis.

Conductivity measurements established that the chloride ligands remain coordinated in acetonitrile.

The redox properties of (PPh₂Me)₄RuCl₂, (PPhMe₂)₄RuCl₂, (PPh₂Me)₂RuCO(CH₃CN)Cl₂ and (PPhMe₂)₃RuCOCl₂ in acetonitrile indicated that these compounds were reduced irreversibly with the uptake of two electrons. Phosphine ligand exchange with the solvent led to the presence of at least two electroactive species in solution. The exchange of phosphine ligands decreased the ease of the reduction of the complexes by 300- 350 mV. The half-wave potentials in solution indicate that the electron density around the metal was not changed appreciably by substituting PPh₂Me and PPhMe₂.

Attempts to reduce (PPh₂Me)₂RuCO(CH₃CN)Cl₂ and (PPhMe₂)₃RuCOCl₂ with 1 % Na-Hg amalagam yielded mixtures of compounds that appeared as a brown powder and an intractable oil, respectively. Characterization of these zerovalent products was not accomplished.

The electrochemical synthesis of (PPh₃)₄Ru(η²-CH₃CN)⋅CH₃CN was carried out electrochemically. When the complex was heated under reflux in hexane, an air-sensitive unsaturated compound, identified as (PPh₃)₄Ru was obtained. The exact nature of the complex was not established.

Recommended Citation

Ibrahim, Nor Azowa, "Syntheses and Electrochemistry of Monosubstituted Carbonyl Complexes of Low Valent Ruthenium" (1986). Masters Theses. 2646.
https://thekeep.eiu.edu/theses/2646