High-Coordinate Gold(I) Complexes With Dithiocarboxylate Ligands

Ferrocene dithiocarboxylate has been introduced into the chemistry of gold(I) and copper(I). First, a modified synthesis of piperidinium ferrocene dithiocarboxylate (1) is reported. Reaction of this reagent with [Au(tht)Cl] in the presence of different phosphines resulted in monomeric, dimeric, and polymeric structures. Although gold(I) is usually two coordinate, mainly three- and four-fold coordinated compounds were obtained by using ferrocene dithiocarboxylate as ligands. The isolated compounds are [(FcCSS)Au(PPh3)(2)] (2) (FcCSS = ferrocene dithiocarboxylate), [(FcCSS)Au-2(dppm)(2)] (3) (dppm = bis(diphenylphosphino)methane), and [(FcCSS)Au(dppf)](n) (4) (dppf = bis(diphenylphosphino)ferrocene) [{(FcCSS)Au}(2)(dppp)] (5) (dppp = bis(diphenylphosphino)propane). The FcCSS ligand shows a remarkable flexible coordination mode. It coordinates either in a monodentate, a chelating, or in a metal bridging mode. In the four gold(I) complexes 2-5 four different coordination modes of the FcCSS ligand are seen. Attempts to extend this rich coordination chemistry to other coinage metals were only partly successful. [(FcCSS)Cu(PPh3)(2)] (6) was obtained from the reaction of piperidinium ferrocene dithiocarboxylate with [(Ph3P)(3)CuCl]. Fe-57 Mossbauer spectroscopy was performed for compounds 2-4. The spectra show isomer shifts and quadrupole splittings that are typical for diamagnetic ferrocenes.