Synthesis and characterisation of [(C5Me4R)2NbS2]2M complexes (M = Fe, Co; R = Me, Et) : organometallic tetrathiometalates with niobocene ligands

Abstract Irradiation of Cp 2 ∗ Nb(η 2 S 2 )H (Cp ∗ = C 5 Me 5 ) 1a in the presence of Fe(CO) 5 gives the CO-free complex [Cp 2 ∗ NbS 2 ] 2 Fe 2a . The core of 2a contains an FeS 4 tetrahedron which is ligated by two niobocene ligands as shown by X-ray diffraction analysis. In the reaction of 1a or Cp 2 x Nb(η 2 S 2 )H (CP x = C 5 Me 4 Et) 1b with Co 2 (CO) 8 , compounds 3a and 3b of the same type are formed. Electrochemical studies of 2a and 3a,b show that they undergo three reversible 1e − steps. The oxidation of 3b exerts a considerable influence on its absorption spectrum. A qualitative EHMO analysis is in agreement with a strong delocalisation of electron density over the whole NbS 2 MS 2 Nb system.