Trans effect in β-diketone complexes of rhodium(I)

✍ Scribed by J.G. Leipoldt; L.D.C. Bok; S.S. Basson; T.I.A. Gerber

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 112 KB
• Volume: 34
• Category: Article
• ISSN: 0020-1693
• DOI: 10.1016/s0020-1693(00)94664-4

✦ Synopsis

It is well known that the carbonyl groups in compounds of the type[Rh@diketone)(CO)J can be substituted by olefines and partially substituted by triphenylphosphine and -arsine [l] . The two car-bony1 groups in symmetrical fldiketones are chemically equivalent. In the case of non-symmetrical Pdiketones it is however necessary to have a knowledge about the relative reactivities of the two carbonyl groups and thus of the relative tnzns effects of the two oxygen atoms of the fl-diketone. This paper deals with the truns effect in complexes of the type [Rh@diketone)(CO)Z] and [Rh(jldiketone)(CO)(PPhh3)1.

The crystal structure determination of [Rh(TTA)-(CO)(PPh,)] , I, prepared by the reaction between [Rh(TTA)(CO),] and triphenylphosphine, PPhJ [l] , showed that the carbonyl group tram to the oxygen atom nearest to the thenoyl group has been displaced [2] (TTA = thenoyltrifluoroacetone). According to this result O(2), in I, has a larger frans effect than O(1). This is in agreement with the polarization theory [3] since the oxygen atom nearest to the CF3-group will be least polarizable as a result of the electron-attracting power of the CF3group.