source: Dalton Transactions year: 2017 volume: 46 first page: 13002 last page: 13009 doi: 10.1039/c7dt03202a
Abstract: The reaction of [Fe2(CO)9] with two representative imidazolium-2-dithiocarboxylate zwitterions derived from common N-heterocyclic carbenes (NHCs) bearing mesityl (IMes) or 2,6-diisopropylphenyl substituents on their nitrogen atoms (IDip) unexpectedly afforded two small bimetallic iron-carbonyl clusters with the generic formula [Fe2(CO)6(μ-κ2-S,S'-κ2-S,S'-S3C·NHC)]. After a brief optimization of the reaction conditions, these two “sulfur-enriched” products were isolated in low yields. They were fully characterized by IR, NMR, UV/Visible, and ESI-MS techniques, and their molecular structures were determined by single crystal X-ray diffraction analysis. The two compounds adopted a butterfly-type disposition in the solid state, with an [Fe2(CO)6] core bridged by the trithioperoxycarboxylate moiety of the in situ generated NHC·CS3 ligands. Bond lengths recorded for the CS3- unit revealed that its negative charge was mostly located on the remote sulfur atom.