In situ NMR observations of the photolysis of cymantrene and methylcymantrene in supercritical fluids. A new technique using high-pressure NMR

John Linehan, Scott L. Wallen, Clement R. Yonker, Thomas E. Bitterwolf, J. Timothy Bays

Research output: Contribution to journalArticle

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Abstract

The in situ photolytic exchange of ethylene and hydrogen for carbon monoxide on cymantrene (cpMn-(CO)3, Cp = η5-cyclopentadienyl) and methylcymantrene (MeCpMn(CO)3, MeCp = monomethyl-η5-cyclopentadienyl) dissolved in subcritical and supercritical solvents (CO2 and ethylene) was investigated by high-resolution, high-pressure 1H NMR over the temperature range from -40 to 150°C and a pressure range from 35 to 2600 bar. Photolytic substitution of ethylene for CO proceeded to completion under all conditions investigated, and only one ethylene was observed to substitute for CO on the manganese complexes even in neat ethylene under extreme conditions of pressure and temperature. Only small amounts of dihydrogen were observed to substitute for CO on cymantrene at 35°C in a binary solvent mixture of CO2/H2 during photolysis. The 1H chemical shifts of the manganese complexes and their ethylene substituted products were found to be linearly dependent on density with temperature and solvent dependence also observed. The spin-lattice relaxation times (T1) of all the solvent and solute species were observed to be inversely proportional to the density of the solvent over the range of conditions investigated. Temperature and concentration dependent phase behavior and solute saturation were also determined for the methylcymantrene and MeCpMn(CO)22-C2H4) solutes in SCF ethylene. These results represent the first NMR detected in situ photolysis study of organometallics in SCF and demonstrate the utility of this technique.

Original languageEnglish
Pages (from-to)10170-10177
Number of pages8
JournalJournal of the American Chemical Society
Volume119
Issue number42
DOIs
Publication statusPublished - 1997

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Supercritical fluids
Photolysis
Carbon Monoxide
Ethylene
Nuclear magnetic resonance
Pressure
Temperature
Manganese
Spin-lattice relaxation
Chemical shift
Organometallics
Phase behavior
manganese cyclopentadienyl tricarbonyl
ethylene
Carbon monoxide
Relaxation time
Hydrogen
Substitution reactions

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

In situ NMR observations of the photolysis of cymantrene and methylcymantrene in supercritical fluids. A new technique using high-pressure NMR. / Linehan, John; Wallen, Scott L.; Yonker, Clement R.; Bitterwolf, Thomas E.; Timothy Bays, J.

In: Journal of the American Chemical Society, Vol. 119, No. 42, 1997, p. 10170-10177.

Research output: Contribution to journalArticle

Linehan, John ; Wallen, Scott L. ; Yonker, Clement R. ; Bitterwolf, Thomas E. ; Timothy Bays, J. / In situ NMR observations of the photolysis of cymantrene and methylcymantrene in supercritical fluids. A new technique using high-pressure NMR. In: Journal of the American Chemical Society. 1997 ; Vol. 119, No. 42. pp. 10170-10177.
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