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|Title:||Part One: Catalytic Reactions of Anion-Exchange Resin Bound Dodecarhodium Triacontacarbonyl Dianion and Its Derivatives and Part Two: Properties and Reactions of Neutral Non-Polar Solvent Soluble Binuclear Complexes|
|Author(s):||Desmond, Michael Joseph|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||In Part One, anion exchange resin supported Rh(,12) (CO)(,30)('2-) and its derivatives are investigated for their catalytic activity. Exchange of the Rh(,12) cluster into the resin under various conditions leads to alteration of the rhodium species.
The resin support was the Dowes 1-X8 anion exchange resin in the chloride form. Exchange of the cluster at room temperature under an inert atmosphere leads to intact Rh(,12) (CO)(,30)('2-) being bound. This material exhibits only limited activity for the hydroformylation of of 1-hexene, accompanied by extensive isomerization of the substrate to 2-hexene, at 100 C and 8 atm of H(,2)/CO.
Exchange of Rh(,12) (CO)(,30)('2-) into the resin at temperatures between 60 and 80 C may have resulted in chloride derivatives of the cluster being bound. Hexene isomerization proceeded at 100 C under hydroformylation conditions. The catalyst was also active in hydrogenating unsaturated hydrocarbons between 25 and 100 C.
In-situ reaction of the resin bound rhodium species with one equivalent of tritolylphosphine produced an active hydroformylation catalyst. The hydroformylation of 1-hexene at 100 C produced 2-methylhexanal as the dominant product. The isolated resin catalyst could be recycled and continued to exhibit significant acitivity without further addition to phosphine. The phosphinated catalyst was also a good hydrogenation catalyst, including the room temperature conversion of nitrobenzene to aniline.
In Part Two, the properties and reactions of metal complexes of the binucleating ligand, 4-tert-butyl-bis-2,6-(N-(S-heptyldithiocarbamate)-formimidoyl)phenol (abbreviated BB), are studied. Binuclear complex formation with two divalent metals requires, in addition to the binucleating ligand, an anion which bridges the two metal centers.
The complexes of first-row transition metals were found to have good solubility in many non-polar or mildly polar organic solvents. These complexes represent the first examples of neutral binuclear complexes which have good solubility in non-basic solvents.
Cyclic voltammetry of the copper and nickel complexes in DMF and CH(,2)Cl(,2) electrolyte solutions exhibited one electron reductions. The reduction potentials for the copper complexes were separted by 400-700 mV indicating the presence of a strong interaction between the metal centers. Investigation of the one electron reduction products of the copper complexes by EPR spectroscopy showed the Cu(I)-Cu(II) to be "locked valence" indicating a physical or chemical process was occurring which results in making the two copper sites nonequivalent. The EPR spectrum of the one electron reduction product of Ni(,2)BB(OEt) indicates the presence of Ni(I) and not a ligand radical.
The mixing of two homonuclear ethoxide bridged complexes in solvents such as toluene or methylene chloride resulted in the production of mixed metal complexes in solution.
The binuclear complexes of nickel undergo reaction with Lewis bases to produce high-spin nickel centers. The reactions could be followed by NMR spectroscopy (contact shift) or by observing changes in magnetism. Monodenate bases reacted readily with one nickel center in the complex, however a synergistic reduction of the Lewis acid strength reduced the reactivity of the second nickel. Bidentate ligands reacted to produce two high spin nickel centers which then undergo a strong antiferromagnetic interaction.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
|Date Available in IDEALS:||2014-12-13|