I. MECHANISTIC ASPECTS OF THE PHOTOCHEMICAL DECOMPOSITION OF DIPHENYLPERMETHYL TITANOCENE AND -ZIRCONOCENE. II. A POLYMER-SUPPORTED DICHLORO(CYCLOPENTADIENYL)RHODIUM(III) CATALYST. III. THERMOCHEMICAL DECOMPOSITION OF DINEOPENTYLPERMETHYL TITANOCENE. IV. HOMOGENEOUS REDUCTION OF CARBON-MONOXIDE.

摘要

I. Qualitative investigations of the mechanisms of photochemical decomposition of diphenylpermethyltitanocene and -zirconocene have been made. Reductive elimination as well as homolytic cleavage of metal-carbon (sigma)-bonds are the two major pathways for photodecomposition of the diphenylpermethylmetallocenes. When benzene-d(,6) was used as the solvent for photolysis of diphenylpermethyltitanocene, biphenyl-d(,0) and biphenyl-d(,5) were found in a ratio of 36/1, indicating that reductive elimination was the much more favorable process. But in the case of diphenylpermethylzirconocene, biphenyl-d(,0) and biphenyl-d(,5) were in a ratio of 1/3, suggesting that the homolytic photocleavage of the (sigma)-bonds was predominant.;Small amounts of N(,2) were absorbed by the photolyzed solution of the title compounds although the hydrogenation of olefins was not appreciable. Nitrogen-15 NMR measurement of the N(,2)-complexes as well as an ESR spin trapping experiment with the photolyzed complexes were also made in this study.;II. The insoluble dichloro(cyclopentadienyl)rhodium(III) complex was successfully anchored to 20% divinylbenzene crosslinked polystyrene by treating polymer-attached cyclopentadiene directly with rhodium trichloride trihydrate. Polymer-supported dichloro(cyclopentadienyl)rhodium(III) proved to be a good hydrogenation catalyst for olefins as well as arenes in the presence of excess triethylamine under 110 psig H(,2) and at 70(DEGREES)C. It could also catalyze the isomerization of allylbenzene in the absence of triethylamine at 85(DEGREES)C. Under 80 psig pressure of CO+H(,2) (1/1) in the presence of triethylamine, this polymer-supported catalyst can be easily converted into the polymer-supported dicarbonyl-(cyclopentadienyl)rhodium(I) catalyst. Mechanisms for the catalyst-preparation, hydrogenation and isomerization were also discussed.;III. Thermal decomposition of dineopentylpermethyltitanocene produced methane (5.1%), ethylene (4.2%), isobutylene (15%), neopentane (75%) and trace amounts of C(,3) and C(,4) hydrocarbons. A titanametallacycle and a titanium-carbene complexes are proposed as intermediates following (gamma)-hydrogen elimination. Deuterium tracer experiments indicated that the hydrogen-abstraction of the titanium-carbene complex to produce methane was from the solvent, and not from the cyclopentadienyl rings.;In the presence of carbon monoxide, moderately large amounts of the dicarbonylpermethylmetallocenes were found, suggesting that the permethylmetallocenes were the intermediates. The discovery of pentamethylcyclopentadiene and 2,3,4,5-tetramethylfulvene in the recovered solvent indicated further photodecomposition of permethylmetallocene. Consequently a more stable intermediate, {(C(,5)Me(,5))(C(,5)Me(,4)CH(,2))M}, is proposed. An oligomeric material was found to be the major final product after photolysis of the title compounds. Although the structure of the oligomeric material remained undetermined, it was believed to be mainly {(C(,5)Me(,5))(C(,5)Me(,4)CH(,2))M} as unit block, because of the finding of pentamethylcyclopentadiene and 2,3,4,5-tetramethylfulvene in a ratio of 1:1.3.;IV. Transition metal carbonyls were used as catalysts to hydrogenate carbon monoxide in the presence of a base under pressures of 40 to 960 psig at the various temperatures. Although the catalytic reaction was not achieved, some interesting reductions of carbonyl ligands on the metal carbonyls were discovered. An aluminum hydride derivative was found to reduce carbon monoxide rapidly at 90(DEGREES)C to produce methane. Sodium hydroxide could initiate the reduction of carbonyl ligands of hexacarbonyltungsten at 150(DEGREES)C under the pressure of CO and H(,2) in the presence of hexamethyldisiloxane. A mechanism is proposed for this reaction.