Conformational Changes and Anion−Cation Interactions in Palladium-Cyclometalated BINAP and Chiraphos Cationic Complexes. A Structural Study via NMR and X-ray Methods
作者:Devendrababu Nama、Pietro Butti、Paul S. Pregosin
DOI:10.1021/om700299b
日期:2007.9.1
The cyclometalated Pd complexes [Pd(A or B)C6H3CH=N(p-CH3C6H4)}(BINAP)](X) (8-13; X = PF6-, BArF-, CF3SO3-, A, B = meta or para ring substituent), [Pd(C6H4CH(CH3)N(CH3)(2))}(S)- or (R)-BINAP)}](CF3SO3) (14a,b), and [Pd(C6H4CH(CH3)N(CH3)(2))}(S,S)- or (R,R)-Chiraphos)}](CF3-SO3) (15a,b) have been prepared, and five of these have been studied by X-ray diffraction. NMR Overhauser measurements reveal that the chiral cyclometalated amine chelate senses the change in the chirality, for both the BINAP and the Chiraphos auxiliaries, and responds by a conformational adjustment of the ring. H-1,F-19-HOESY data for both 14 and 15 suggest differences between the diastereomers 14a,b (and 15a,b). PGSE diffusion data for these salts are reported.