Rhodium( I ), Palladium( II ) and Platinum( II ) Coordination Chemistry of the Short‐Bite Chiral Ligands ( S c )‐ N , N ‐Bis(diphenylphosphanyl)‐ sec ‐butylamine, ( R a , R a )‐ N , N ‐Bis(binaphthylphosphonito)phenylamine and ( R a , S c )‐ N ‐(Diphenylphosphanyl)‐ N ‐(binaphthylphosphonito)‐ sec ‐butylamine

The new short‐bite chiral ligands ( S c )‐ N , N ‐bis(diphenylphosphanyl)‐ sec ‐butylamine [( S c )‐ 1 ], ( R a , R a )‐ N , N ‐bis(binaphthylphosphonito)phenylamine [( R a , R a )‐ 2 ] and ( R a , S c )‐ N ‐(diphenylphosphanyl)‐ N ‐(binaphthylphosphonito)‐ sec ‐butylamine [( R a , S c )‐ 3 ] have been treated with rhodium( I ), palladium( II ) and platinum( II ) substrates. The ( S c )‐ 1 ligand reacts with [Pd(C 6 H 5 CN) 2 Cl 2 ], [Pt(COD)Cl 2 ] and [Rh(COD)(THF) 2 ]PF 6 to afford the products [Pd( S c ‐ 1 )Cl 2 ] ( 4 ), [Pt( S c ‐ 1 )Cl 2 ] ( 5 ) and [Rh(COD)( S c ‐ 1 )]PF 6 ( 6 ), respectively, in high yields. By bubbling CO to a CH 2 Cl 2 solution of 6 , we formed the dicarbonyl species [Rh(CO) 2 ( S c ‐ 1 )]PF 6 ( 7 ), which is stable only in solution under CO. Compounds 4 and 5 were characterized additionally by X‐ray diffraction studies. The ligand ( R a , R a )‐ 2 reacts with [Pd(C 6 H 5 CN) 2 Cl 2 ] and [Pt(COD)I 2 ] to give [Pd( R a , R a ‐ 2 )Cl 2 ] ( 8 ) and [Pt( R a , R a ‐ 2 )I 2 ] ( 9 ), respectively; the reaction with [Rh(CO) 2 Cl] 2 or [Rh(COD)(THF) 2 ]PF 6 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 , S c ‐ 3 )Cl 2 ] ( 10) and [Pt( R a , S c ‐ 3 )I 2 ] ( 11 ) were obtained in the analogous reactions using the asymmetric ( R a , S c )‐ 3 ligand. This ligand reacted with [Rh(CO) 2 Cl] 2 in a 2:1 molar ratio in hexane to give a mixture of products in almost equal amounts. The 31 P{ 1 H} NMR spectrum recorded in CDCl 3 allowed us to identify the chelate [Rh( R a , S c ‐ 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 ( R a , R a )‐ 2 and ( R a , S c )‐ 3 , at ligand/metal ratios of 1:1 and 1:2, were unstable under the experimental conditions used (CO/H 2 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)