Study of the Bonding Properties of the New Ligands C 5 H 3 N(2-R‘)(6-CH 2 PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o -Anisyl, R‘ = Me

The bonding properties of the optically active chiral-at-P polydentate ligands C 5 H 3 N(2-R‘)(6-CH 2 PPhR) (R = Me, R‘ = H, Me; R = o -anisyl, R‘ = H, Me) and the achiral ligand C 5 H 3 N(2-Me)(6-CH 2 PPh 2 ) toward (COD)Rh + are reported. The results show that steric hindrance of the 2-position of the pyridyl ring induces a labile character of the Rh−N bond. Moreover, for R = o -anisyl and R‘ = Me, a dynamic competition for bonding between the N- and O-donating centers is observed. Comparison of the solid state structures of complexes [Rh(COD)(C 5 H 4 N(2-CH 2 PPhMe)][BF 4 ] and [Rh(COD)(C 5 H 3 N(2-Me)(6-CH 2 PPh 2 )][BF 4 ] shows a significant bond lengthening of the Rh−N bond in the latter complex, consistent with its fluxional behavior observed in solution.