Département de chimie moléculaire

On the quest of heterometallic mixed-valence MM'X chains, the authors prepd. two stable discrete bimetallic compds.: the reduced (PPN)[ClNi($μ$-OSCPh)4Pt] (1)(PPN = bis(triphenylphosphine)iminium; OSCPh = benzothiocarboxylato) and the oxidized [(H2O)Ni($μ$-OSCPh)4PtCl] (2) species. The role of the aqua and chlorido axial ligands is crucial to facilitate oxidn. of the {\{}Ni($μ$-OSCPh)4Pt{\}} core. Exptl. and theor. analyses indicate that a NiPt-Cl/Cl-NiPt isomerization process occurs in the oxidized species. The electronic structure of the reduced system shows two unpaired electrons, one located in a dx2-y2 orbital of the Ni(II) ion and a second in the antibonding dz2-dz2 combination from the Ni(II) and Pt(II) centers. Oxidn. occurs by removing one electron from this second multicenter MO. Although the mixed-valence character of the oxidized species makes the isolation of MM'X chains very attractive, such polymeric structure is prevented by the low Pt-Cl···Ni interaction energy and the high tendency of Ni centers to coordinate water mols. Thus, this work offers valuable insights and hints to engage the prodn. of heterometallic mixed-valence MM'X chains, which still is a challenging task. [on SciFinder(R)]