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} = Pt3(μ-​PBut2)​3(CO)​2] (1:2 molar ratio) in diethylamine gives in high yields the bicluster deriv. [{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 soln., as suggested by NMR Diffusion Ordered Spectroscopy (DOSY) and 1D Rotating-​frame Overhauser Enhancement (ROE) measurements. Compd. 3 exhibits a rich redox behavior, with a crowded sequence of six one-​electron oxidn. processes, the electrode potentials of which were evaluated by digital simulations. On the basis of a spectroelectrochem. study, the first two oxidns. are assigned to the iron centers of the diferrocenyl unit and the subsequent four electrons are removed from the {Pt3} units.