Axial ligand substitution reactions of head-to-head α-pyridonato-bridged Pt(III) binuclear complexes bearing various equatorial ligands with chloride ion and olefin

In this study, axial ligand-substitution reactions of head-to-head (HH) α-pyridonato-bridged platinum(III) binuclear complexes bearing equatorial amine ligands (L = MeNH₂, EtNH₂, and L–L = ethylenediamine (en), and N,N′-dimethylethylenediamine (Me₂en)) [(Cl)(NH₃)₂Pt(μ-α-pyridonato)₂Pt(L)₂(Cl)]²⁺ are synthesized, and the axial ligand substitution on these complexes with chloride ions are kinetically investigated in acidic aqueous solution. For these complexes, the formation reactions of the dichloro complexes from the monochloro complexes proceeded through three parallel reaction pathways, in contrast to those for the HH tetraammine amidato-bridged platinum (III) binuclear complexes. The effects of equatorial amine ligands as well as the bridging ligands on the axial ligand substitution are discussed. The reaction of [(H₂O)(NH₃)₂Pt(μ-α-pyridonato)₂Pt(en)(OH₂)]²⁺ with p-styrenesulfonate is also kinetically investigated.