Fischer type carbene ligands in dinuclear complexes

A large number of iron and ruthenium dinuclear complexes containing heteroatom substituted carbene ligands have been obtained by two different synthetic routes. The first method consists in reacting heteroatom substituted -carbyne cationic complexes with CN^– ion. The second involves the displacement of the SMe₂ molecule in the sulfonium [Fe₂{-C(CN)(SMe₂)}(-CO)(CO)₂CP₂]SO₃CF₃ by appropriate nucleophilesX^– (X=OR, SR, NR₂, PR₂). Spectroscopic (IR, NMR) and structural investigations together with reactivity studies on these complexes have greatly contributed to better understanding the factors which favor bridging vs. terminal coordination of heteroatom substituted carbene ligands.