[RH(LL)(CO)(PPH3)] COMPLEXES AS MODELS FOR CATALYTIC PROCESSES: X-RAY[1,2] vs 13P/13 C NMR[3] vs IODOMETHANE OXIDATIVE ADDITION REACTIVITY[1] CORRELATIONS. A. Roodt, GJJ Steyn, L Damoense, JA Venter, SS Basson and W Purcell, Dept. of Chemistry, University of the Orange Free State, Bloemfontein 9300, South Africa, and YS Varshavsky, MR Galding, TG Cherkasova and LV Osetrova, Lebedev, National Rubber Institute, 1 Galspaskaja str., St Petersburg 198035, Russia.
X-ray structure determinations of ca. 20 complexes of the type, [Rh(LL'-bid)(CO)(PPh3)], LL'-bid = symmetrical/unsymmetrical monocharged bi-dentate ligands [such as acac, Sacac, ox, cupf, dmavk (dimethylaminovinyl-ketonate), macsm (methyl (2-methylamino)-1-cyclopentene-1-dicarboxylate) etc.] containing different variations of oxygen, nitrogen and sulphur as coordinating atoms, were studied. These will be discussed briefly in terms of isomer distribution and bond strength manipulation in the Rh(I) coordination polyhedron.
Next, a correlation between this structural results and 13P/13C data, relating to the Fermi contact term, will be presented and discussed.
Finally, an attempt to correlate both the above with the reactivity observed in these complexes in terms of both the formation of the [Rh(LL')(CO)(PPh3)] complexes from the corresponding [Rh(LL)(CO)2)], as well as the stereochemistry and the reactivity of these complexes towards oxidative addition by iodomethane, forming Rh(III)-alkyl and Rh(III)-acyl products in the process, will be presented.
1. Steyn, GJJ; Roodt, A; Leipoldt, JG: Inorg. Chem. 1992, 31, 3744.
2. Damoense, L; Purcell, W; Roodt, A: Rhodium Express 1994, 5, 10.
3. Galding, MR; Cherkasova, TG, Varshavsky, YS, Osetrova, LV, Roodt, A:
Rhodium Express 1995, 9, 36, and refs within.