Inorganic Chemistry, Vol.53, No.11, 5438-5446, 2014
Synthesis of V/Fe/S Clusters Using Vanadium(III) Thiolate Complexes Bearing a Phenoxide-Based Tridentate Ligand
Vanadium(III) thiolate complexes carrying a phenoxide-based tridentate ligand were prepared from the reactions of V(NMe2)(4) with the protonated Fe OH forms of tridentate ligands (H-2(O,P,O) = bis(3,5-di-tert-butyl-2-hydroxypheny)-phenyl-phosphine or H-2(O,O,O) = bis(3,5-di-tert-butyl-2-hydroxyphenyl)phenyl-phosphineoxide) and thiols (HSR; R = mesityl (Mes), 2,4,6-(Pr3C6H2)-Pr-i (Tip)). The vanadium-thiolate complexes were subjected to the V/Fe/S cluster synthesis via treatment with an Fe(II) thiolate complex [(TipS)Fe](2)(mu-SDmp)(2) (4, Dmp = 2,6-(mesityl)(2)C6H3) and elemental sulfur in toluene, leading to the formation of two new V/Fe/S clusters. One is an edge-bridged double-cubane-type [VFe3S4]-[VFe3S4] cluster [(O,P,O)VFe3S4(SDmp)(HNMe2)](2) (5) having face-capping tridentate (O,P,O) ligands on vanadium atoms. The other is a [VFe3S4-Fe] cluster [(mu-O,O,O)VFe3S4(SDmp)(STip)Fe(mu-SDmp)] (6), the core of which consists of a cubane-type [VFe3S4] unit and an external iron atom. The external iron is bound to an SDmp ligand and two oxygen atoms of the tridentate (O,O,O) ligand. Cluster 6 is structurally relevant to the active site of nickel-dependent CO dehydrogenase, and their common structural features include a cubane-type unit with a heterometal, one more iron atom besides the cubane unit, and a bridging ligand between the external iron and the heterometal of the cubane unit.