Conformational Changes and Anion−Cation Interactions in Palladium-Cyclometalated BINAP and Chiraphos Cationic Complexes. A Structural Study via NMR and X-ray Methods

The cyclometalated Pd complexes [Pd{(A or B)C6H3CHN(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)}](CF3SO3) (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. 1H,19F-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.