1H 13C NMR investigation of E/Z-isomerization around CN bond in the trans-alkene-Pt(II)imine complexes of some ketimines and aldimines

Ketimines (K1, K2) and aldimines (A1, A2, and A3) were prepared from unsubstituted acetophenone and/or benzaldehyde and primary amines (i-PrNH2, i-BuNH2 and t-BuNH2). These imines were reacted with Zeise’s salt (potassium ethenetrichloroplatinate(II)) to produce the respective complexes, namely, PtK1, PtK2, PtA1, PtA2, and PtA3. 1H, 13C, and 195Pt-chemical shifts of the ligands and their complexes were studied to investigate the nature and mode of isomerization around CN bond. The aldimines and their complexes were obtained as a single isomer. On the other hand, the ketimines and their complexes were obtained as a mixture of E/Z-isomers. It was found that the aldimine- and ketimine-platinum complexes undergo slow E/Z-isomerization in solution as evidenced from NMR spectra.