Photochemistry of acetylacetonato-, trifluoroacetylacetonato-, and hexafluoroacetylacetonato-dicarbonyl-rhodium and -iridium complexes in frozen gas matrices at 12 K. Infrared spectroscopic evidence for carbon monoxide dissociation and chelate ring-opening processes
- 1 January 1982
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 9,p. 1777-1782
- https://doi.org/10.1039/dt9820001777
Abstract
Infrared spectroscopic evidence, including 13CO labelling and energy-factored CO force-field fitting, is presented to show that on photolysis of [M(CO)2L](L = RCOCHCOR′; R,R′= CH3 or CF3; M = Rh or Ir) complexes at high dilution in CH4, Ar, CO, and N2 matrices at 12 K new species [M(CO)L], [M(CO)2(L*)](L*= unidentate form of L), and [M(CO)(N2)L] are produced. The results are discussed in relation to the mechanisms of thermal reactions in solution. In particular, the reversibility of the reaction [M(CO)2L][M(CO) L]+ CO and the dominance of this reaction indicates that the hitherto discounted dissociative pathway should be reconsidered. Some evidence is also found for the chelate ring opening to give [ M(CO)2(L*)] species, but no evidence was found for expanded-co-ordination-number species corresponding to the previously proposed associative mechanism for ligand-exchange and substitution reactions.Keywords
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