Abstract Displacement of piperidine from Ru (COD)(piperidine)-trans-(H) Cl (I) by 1, 4-diaza- 1, 3-dienes (DAD: RN CR′ CR′ NR) gives the complexes cis-Ru (COD)(DAD)-(H) Cl (III). With relatively bulky DAD ligands the complexes III are unstable and are converted into compounds IV, which are also formed from III on heating. Complexes III are not accessible from Ru (COD)(DAD) Cl 2 (V). If the analogous starting material involving a ...