Dynamic behaviour in solution of some benzo[h]quinoline and 8-methylquinoline complexes of palladium(II)

Abstract

Enantiomeric forms of [Pd(dmp)L(OH₂)][ClO₄][dmp = 2-(dimethylaminomethyl)phenyl, L = benzo[h]quinoline (bquin) or 8-methylquinoline (8Me-quin)] rapidly interconvert in (CD₃)₂CO solution to give coalescence of the methyl ¹H n.m.r. singlets of the dmp ligand. A kinetic study of this process for L = bquin supports a unimolecular displacement of H₂O associated with the ligand L rotating from largely above to largely below the co-ordination plane. This is supported by the non-dynamic nature of [Pd(dmp)L(NO₃)]. Addition of small amounts of D₂O to the (CD₃)₂CO solution of [Pd(dmp)(bquin)(OH₂)][ClO₄] considerably reduces the rate of inversion, which probably results from a breakdown of the more reactive ion pairs.