The reaction of [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}(μ3-S)(μ3-CS)] and related complexes with carbon disulfide. Synthesis, structure and reactivity of [{Co(η5-C5H5)}2{Fe(CO)(L)}(μ3-S)(μ3-C2S3)] derivatives (L = PR3and CNR)

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[{Co(η5-C5H5)}2{Fe(CO)(L)2}(μ3-S)(μ3-CS)] complexes 1 where (L)2 = (a) (CO)(PPh3), (b) (CO){P(OPh)3}, (c) (CO)(PBun3), (d) (CNMe)2 and (e) (CNMes)2 (Mes = 2,4,6-Me3C6H2), but not (CO)(CNMes), react with CS2 under reflux to give [{Co(η5-C5H5)}2{Fe(L)2}(μ3-S)(μ3-C2S3)], 2, in which a CS2 molecule has been incorporated into a FeSC(S*)SC heterocycle with a trithiocarbonate moiety bridging the Fe–C cluster edge. Clusters 2 react with incoming ligands either by simple ligand substitution, or by displacement of CS2 to form clusters of type 1. The exocyclic sulfur atom S* is nucleophilic and with electrophiles E forms [{Co(η5-C5H5)}2{Fe(L)2}(μ3-S)(μ3-C2S3E] adducts which contain S*→E bonds where E = Me+ [3]+, Et+ [4]+, HgCl2 [5], and I4 (or I+) [6]. The clusters 2a–c and the [3]+ and [4]+ derived from them are chiral as indicated by their NMR spectra, and do not racemize on the NMR timescale. The structures of 2a·2C6H6 and [3a]I·C6H6·CHCl3 are reported. Cluster 2a contains a very short Fe–Cμ bond as compared with 1a, and it is suggested that in many respects the FeSC(S)SCμ ring is best regarded as a metallo-1,3-dithiole-2-thione (or metallovinyl trithiocarbonate) with a Fe–Cμ double bond which, on alkylation at the exocyclic S*, adopts a more delocalised electronic structure with a longer Fe–Cμ bond. Spectroscopic and electrochemical data for the new compounds are discussed.