Photochemical Formation of Mononuclear Bis and Tris Ethylene Complexes from Irradiation of Iron Pentacarbonyl or Triruthenium Dodecarcarbonyl: Species Involved in Catalytic Alkene Isomerization.
Interim technical rept.,
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF CHEMISTRY
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In alkane or CF3C6F11 solutions which contain excess C2H4, near-UV irradiation of RuCO4C2H4, formed quantitatively in situ from visible flight wavelength 420nm irradiation of Ru3CO12, yields RuCO3C2H42 at 298K. At temperatures below 253K further substitution can be effected photochemically to give trans-RuCO2C2H43. Near-UV irradiation of RuCO4C2H4 in rigid, C2H4-saturated, 3-methylpentane glasses at 90K yields RuCO3C2H42, but further CO loss to give cis-RuCO2C2H4 is observed after only approx. 5 consumption of RuCO4C2H4. Isomerization of photogenerated cis-RuCO2C2H43 to trans-RuCO2C2H43 is only observed on warming the glass above 210K. Prolonged irradiation of photogenerated cis-RuCO2C2H43 at 90K yields loss of additional CO to give a monocarbonyl complex, formulated as RuCOC2H44, which reacts on warming with photoreleased CO to initially regenerate cis-RuCO2C2H43. The photochemistry of FeCO2C2H43 could only be detected by IR spectroscopy at temperatures below 210K. The new results show that species previously formulated as Fe2CO6alkene2 are in fact FeCO3alkene2. In solution, the MCO3C2H42 M Fe, Ru and RuCO2C2H43 are substitutionally labile and may serve as versatile reagents in preparative chemistry.
- Radiation and Nuclear Chemistry