Cyclometallation of phenylhydrazones: Synthesis, reactivity, crystal structure analysis and novel trinuclear palladium(II) cyclometallated compounds with [C,N,N′] terdentate ligands

Cyclometallated complexes derived from pyrimidin- and pyridazinehydrazones: Structural evidence of intermolecular “chelate metal ring” π–π interactions

“…9 Hz]; no coupling was observed to the terminal phosphorus nuclei. These data are in accordance with a disposition in which the metallated ring is nearly perpendicular to the plane defined by the three phosphorus atoms [23,26,28,29]. The conductivity data in acetonitrile solution showed the compounds were 1:1 electrolytes.…”

“…Treatment of the latter with neutral ligands such as tertiary mono-or diphosphines produces cleavage of the metal-Ń bond prior to ring-opening of the fivemembered metallacycle; however, removal of the chlorine ligand by reaction with a silver (I) salt yields a vacant coordination site that may be occupied by the phosphine ligand, precluding metalÀnitrogen bond cleavage. Nevertheless, in some cases the strength of the Pd-N bond prevents ring-opening, even when an excess of mono-or diphosphine is used [28]. Pd-N bond cleavage may also be achieved by reaction with the tertiary triphosphine (Ph 2 PCH 2 CH 2 ) 2 PPh (triphos) upon chelation.…”

“…Pd-N bond cleavage may also be achieved by reaction with the tertiary triphosphine (Ph 2 PCH 2 CH 2 ) 2 PPh (triphos) upon chelation. However, in spite that the tendency of triphos to act as a chelating ligand is patent [23,26,29], in some cases it may behave as a bridging ligand coordinating three different cyclometallated moieties [28,30].…”

Synthesis of Mono-, Di-, and Tripalladated 1,3,5-Benzenetricarboxaldehyde Complexes

“…The chemistry of arylpalladium complexes is a topic of great interest because of the involvement of these compounds in many important palladium-catalyzed carbon−carbon and carbon−heteroatom bond-forming reactions . Suitable substituents ortho to the Pd atom may lead to cyclopalladated compounds, − influence the reactivity of the complexes, − ,− or participate in the formation of organic compounds. ,,,− Consequently, there have been intensive studies of the synthesis of Pd(II) aryl complexes , and of their reactivity, ,− ,,,,, to understand the mechanism of such catalytic or stoichiometric reactions. This rich chemistry of ortho-substituted aryl Pd(II) complexes has prompted us to explore the possibility of synthesizing polypalladated benzene derivatives with functionalized organic substituents ortho to each Pd.…”