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)­Au2(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)3CuCl]. 57Fe–Mössbauer spectroscopy was performed for
compounds 2–4. The spectra show isomer
shifts and quadrupole splittings that are typical for diamagnetic
ferrocenes.