Rational Synthesis and Complexation Behavior of the Bidentate Lewis Acid 1,2-Bis(chloromercury)ferrocene

1,2-Disubstituted ferrocenes represent an interesting, yet underdeveloped class of redox-active bidentate Lewis acids. We describe here a new rational synthesis of 1,2-bis(trimethylstannyl)ferrocene ( 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, [Bu 4 N]Cl, and [PPh 4 ]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 [Bu 4 N]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 [Bu 4 N] and [Ph 4 P] counterions, respectively.