Synthesis, Structure, and Electrochemistry of the Dicluster Molecular Pincer [Pt3(μ-PBut2)3(CO)2]2(μ-1’,1’’’-diethynylbiferrocene)

The CuI catalyzed dehydro-halogenation of 1′,1″′- diethynylbiferrocene and {Pt3}Cl [{Pt3} = Pt 3(μ-PBut2)3(CO)2] (1:2 molar ratio) in diethylamine gives in high yields the bicluster derivative [{Pt3}CC-(η5-C5H4) Fe(η5-C5H4)]2, 3, in which two platinum triangles are connected by a diethynylbiferrocene spacer. In the structure of 3, confirmed by a diffractometric study, the two {Pt3} fragments lie, perfectly eclipsed, on the same side of the biferrocenyl moiety; this folded structure is also preferred in solution, as suggested by NMR Diffusion Ordered Spectroscopy (DOSY) and 1D Rotating-frame Overhauser Enhancement (ROE) measurements. Compound 3 exhibits a rich redox behavior, with a crowded sequence of six one-electron oxidation processes, the electrode potentials of which have been evaluated by digital simulations. On the basis of a spectroelectrochemical study, the first two oxidations are assigned to the iron centers of the diferrocenyl unit and the subsequent four electrons are removed from the {Pt3} units.