Diferrocenylmercury-Bridged Diphosphine: A Chiral, Ambiphilic, and Redox-Active Bidentate Ligand

A diphosphine chelate ligand with a wide and flexible bite angle, a unique stereochemical environment, and redox-active and ambiphilic character is reported. Initially generated as its HgCl2 complex by reaction of 1,2-fc(PPh2)-(SnMe3) (fc = ferrocenediyl) with HgCl2 in acetone, treatment with [n-Bu4N]CN readily liberates the free chiral bidentate ligand. An intermolecular ClHg-Cl-Hgfc(2) (2.9929(13) angstrom) action that is unprecedented in ambiphilic ligand chemisn in the solid structure of Hg(fcPPh(2))(2)center dot HgCl2 where the bridging mercury atom acts as a sigma-acceptor. Furthermore, a bis-[Rh(COD)Cl] complex is introduced, which displays relatively short Rh center dot center dot center dot Hg contacts of 3.4765(5) and 3.4013(1) angstrom. Wiberg, indices of 0.12 are determined for these Rh center dot center dot center dot Hg interactions and an AIM analysis reveals bond paths with an electron density rho(r) of 1.2 x 10(-2) and 1.4 x 10(-2) e/a(0)(3) at the bond critical points.