765277-43-8Relevant academic research and scientific papers
Rhodium(I), palladium(II) and platinum(II) coordination chemistry of the short-bite chiral ligands (Sc)-N,N-bis(diphenylphosphanyl)-sec- butylamine, (Ra,Ra)-N,N-bis(binaphthylphosphonito) phenylamine and (Ra,Sc)-N-(diphenylphosphanyl)-N- (binaphthylphosphonito)-sec-butylamine
Calabro, Gianpiero,Drommi, Dario,Graiff, Claudia,Faraone, Felice,Tiripicchio, Antonio
, p. 1447 - 1453 (2004)
The new short-bite chiral ligands (Sc)-N,N- bis(diphenylphosphanyl)-sec-butylamine [(Sc)-1], (R a,Ra)-N,N-bis(binaphthylphosphonito)phenylamine [(R a,Ra)-2] and (Ra,Sc)-N- (diphenylphosphanyl)-N-(binaphthylphosphonito)-sec-butylamine [(R a,Sc)-3] have been treated with rhodium(I), palladium(II) and platinum(II) substrates. The (Sc)-1 ligand reacts with [Pd(C 6H5CN)2Cl2], [Pt(COD)Cl2] and [Rh(COD)-(THF)2]PF6 to afford the products [Pd(S c-1)Cl2] (4), [Pt(Sc-1)Cl2] (5) and [Rh(COD)(Sc-1)]PF6 (6), respectively, in high yields. By bubbling CO to a CH2Cl2 solution of 6, we formed the dicarbonyl species [Rh(CO)2(Sc-1)]PF6 (7), which is stable only in solution under CO. Compounds 4 and 5 were characterized additionally by X-ray diffraction studies. The ligand (Ra,R a)-2 reacts with [Pd(C6H5CN)2Cl 2] and [Pt(COD)I2] to give [Pd(Ra,R a-2)Cl2] (8) and [Pt(Ra,Ra-2)I 2] (9), respectively; the reaction with [Rh(CO)2Cl] 2 or [Rh(COD)(THF)2]PF6 affords a mixture of mono- and binuclear compounds, in which the ligand is oxidized to the corresponding phosphonate or is partially hydrolysed. The compounds [Pd(R a,Sc-3)Cl2] (10) and [Pt(Ra,S c-3)I2] (11) were obtained in the analogous reactions using the asymmetric (Ra,Sc)-3 ligand. This ligand reacted with [Rh(CO)2Cl]2 in a 2:1 molar ratio in hexane to give a mixture of products in almost equal amounts. The 31P{1H} NMR spectrum recorded in CDCl3 allowed us to identify the chelate [Rh(Ra,Sc-3)(CO)Cl] (12); the nature of the accompanying dinuclear species 13 is not clear. The catalytic systems formed by [Rh(acac)(CO)2] and the ligands (Ra,Ra)-2 and (Ra,Sc)-3, at ligand/metal ratios of 1:1 and 1:2, were unstable under the experimental conditions used (CO/H2 pressure of 50 atm and temperature of 40 °C) for the hydroformylation of styrene; instead, metallic rhodium was afforded together with unidentified decomposition products. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
