Polyketones (M w = 56 000-87 000 g mol 21 ) with very narrow molecular weight distributions have been obtained by CO/tertbutylstyrene copolymerisation in supercritical carbon dioxide using palladium complexes with perfluorinated bipyridine and phenanthroline ligands.

Palladium allylic systems containing modular chiral dithioether ligands were chosen as catalysts for a systematic study of homodonor ligands in allylic alkylation reactions. For this purpose, new type-DMPS (4-6) and -DEGUS (8, 9) ligands were synthesized. Dithioethers 4-6 afforded high activities and excellent selectivities in all Pd-catalyzed allylic reactions. Particularly the Pd/6 catalytic system provided b-VIII with an ee > 99% and a regioselectivity l/b (VIII) ) 1/1.6. A family of intermediate complexes containing several allyl groups (symmetrical, 13-16 and 20, and nonsymmetrical, 17-19, moieties) and dithioether ligands (4-6, 8, 9, 11, and 12) is described. The complexes were fully characterized both in solution and in the solid state. X-ray structures of four of these complexes (16-18 and 20) were determined. The diastereomers present in solution were studied by NMR spectroscopy, and in some cases it was possible to establish a relationship between the diastereomeric excesses and the selectivities found in the catalytic process.

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The new P‐donor ligands PPh3–n(OC9H19)n (n = 3, 2, 1) containing branched alkyl chains were synthesised and their coordination to RhI and PdII studied. The X‐ray structure of [Rh{PPh2(OC9H19)}4]PF6 was determined. Reaction of the [Rh(acac)(CO)2]/PPh3–n(OC9H19)n systems with CO/H2 at 5 atm and 80 °C in toluene led to the formation of [RhH(CO){PPh3–n(OC9H19)n}3] as the main species. The Rh‐catalysed hydroformylation of 1‐octene with these ligands was investigated in supercritical carbon dioxide (scCO2) and toluene as solvents. Although the catalytic systems are not soluble in scCO2, they are active. The activities are higher in toluene than in scCO2 but the selectivities for aldehydes in the case of the phosphonite derivative are higher in the supercritical medium than in toluene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)