Régis Reau

Phospholes as ligands for rhodium systems in homogeneously-catalysed hydroformylation reactions: Part 1. Stereoelectronic properties of the ligands and hydroformylation of 1-hexene

Abstract The stereoelectronic properties of various phospholes were determined and discussed in terms of Tolmans electronic ν and steric θ parameters. The selected phospholes, associated with rhodium, were used in the catalytic hydroformylation of 1-hexene and compared to triphenylphosphine under typical hydroformylation conditions (80 °C, 20 bar syngas). One phosphole, namely 1,2,5-triphenylphosphole (TPP), has been found to be by far superior to triphenylphosphine (about 10 times more active and 10% more selective). Most importantly, the rhodium-TPP system does not seem to be sensitive to the P/Rh ratio.

The Dramatic Influence of Diamidoamine Ligands on the Structure and Reactivity of Low-Valent Tin and Bismuth Derivatives

The dilithium salts of N-methyl-N′,N′′-bis(diisopropyl)- and -(trimethylsilyl)-diethylenetriamine 1a,b react with SnCl2 affording the corresponding stannylenes 2a,b in 60 and 80% yield, respectively. Compound 1b also reacts with BiCl3 to give the bismuth chloride 5 (90% yield). Derivatives 2b and 5 have a symmetrical bicyclic structure and are monomeric both in solution and in the solid state. When 2b is treated with BiCl3 or PCl3, an oxidation reaction leads to the hypercoordinated tin(IV) dichloride 3 (58% yield), or a transmetallation gives rise to the oniophosphane 4 (95% yield), respectively. Transmetalation reactions also occurred when 5 was treated with AlCl3, GaCl3 or SnCl2 affording the corresponding aluminum chloride 6 (81% yield), gallium chloride 7 (38% yield) or tin dichloride 3 (38% yield). The observed reactivity for 2 and 5 is compared to that reported for Veiths stannylene or bismuth chloride.