Comparing the Reactivity of Benzenedithiolate- versus Alkyldithiolate-Bridged Fe2(CO)6 Complexes with Competing Ligands



The reactivity of [(μ-X2bdt)Fe2(CO)6] [(bdt)1, X2bdt = 3,6-disubstituted bezenedithiolate; X = H, Cl] with ligands of different donor strengths is investigated and compared to that of [(μ-pdt)Fe2(CO)6] [(pdt)1, pdt = propyldithiolate] and [(μ-edt)Fe2(CO)6] [(edt)1, edt = ethyldithiolate]. Strong donor ligands (L = CN, PMe3) when added to (bdt)1 lead to mononuclear [(bdt)Fe(L)2(CO)2], (bdt)6(L), in a disproportionation and fragmentation reaction, while simple ligand-substitution reactions occur on (edt)1 and (pdt)1 under identical conditions. In the presence of weaker ligands such as secondary amines or dmf, the alkyldithiolate-bridged complexes are unreactive, while (bdt)1 transforms to an O2-sensitive, magnetically uncoupled species, potentially a mononuclear FeI complex coordinated by bdt and at least 2 CO ligands.