Ruthenium(II) complexes containing N(4)-tolyl-2-acetylpyridine thiosemicarbazones and phosphine ligands: NMR and electrochemical studies of cis–trans isomerization

[Ru(HL)(PPh3)2Cl]Cl complexes have been obtained in which HL = N(4)-ortho (complex 1), N(4)-meta (complex 2) and N(4)-para-tolyl 2-acetylpyridine thiosemicarbazone (complex 3). NMR and electrochemical studies indicate that both cis and trans isomers exist in solution, and that the cis isomers are converted into the trans isomers with time. Crystal structure determination of (1) reveals that the trans isomer is formed in the solid state.