Rational synthesis and complexation behavior of the bidentate lewis acid 1,2-bis(chloromercury)ferrocene

Article abstract of DOI:10.1021/om0506567

1,2-Disubstituted ferrocenes represent an interesting, yet underdeveloped class of redoxactive bidentate Lewis acids. We describe here a new rational synthesis of 1,2-bis(tri-methylstannyDferrocene (2) and its high yield conversion to 1,2-bis(chloromercury)ferrocene (3). X-ray crystal structures for complexes of the bidentate Lewis acid 3 with DMSO, [Bu₄N]Cl, and [PPh₄]Cl were obtained. In all cases the two Hg atoms form reverse chelates with the nucleophile. With DMSO a 1:1 complex is formed, in which DMSO is coordinated from the endo side of ferrocene. Two molecules of 3 are used in the binding to the chloride anion. Different modes are realized with the two different counterions. In the complex with [Bu₄N]Cl the chloride ion is coordinated from the exo side of both ferrocenes, while with [PPh ₄]Cl the chloride ion is endo with respect to one and exo with respect to the other ferrocene moiety. Layered and channel-like supramolecular structures are realized with [Bu₄N] and [Pt₄P] counterions, respectively.