Rh(TTA)(CO)(PPhs)]
[5] (TTA = thenoyltrifluoroacetone) and [Rh(ACA)(CO),]
[6] were published. Products of substitution reactions of CO by PPh3 and P(OPh)s in Rh@-diketone)(CO)z complexes (where @-diketone: acetylacetone, thenoyltrifluoroacetone, trifluoroacetone, benzoyltrifluoroacetone, naphthoyltrifluoroacetone)
were examined by IR and NMR. Reactions with PPhs produced the compounds containing one CO group, i.e. Rh@diketone)(CO)-(PPh3). In the case of asymmetric fl-diketones, two isomers were observed in solution. The presence of free phosphine caused labilization of the coordination sphere of complexes followed by fast exchange between the free and the coordinated phosphine. Reaction with P(OPh)s produced Rh@-diketone)-[P(OPh)3]2 or Rh@-diketone)(CO)[P(OPh)s] complexes, depending on the amount of P(OPh)s used.
Except for the X-ray investigations no spectroscopic data were reported for these complexes. We have described earlier the synthesis and the physicochemical data for the phosphite complexes [Rh-WMCW'W'hMI and [WAW@'@Ph)d21
[7, 81 ; we report here our results achieved for the phosphite complexes of that type with the other fl-diketones. Activity of the [Rh(fidiketone)(CO)2] -type complexes in substitution reactions has been studied recently by Leipold et al. [9], who also noted an effect of P-diketone substituents on the rate of substitution of CO ligands by cyclooctadiene.
The NMR results indicate considerable delocalization of the electron density in these compounds.