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 = PR3 and CNR)

[{Co(eta(5)-C5H5)}(2){Fe(CO)(L)(2)}(mu(3)-S)(mu(3)-CS)] complexes 1 where (L)(2) = (a) (CO)(PPh3), (b) (CO){P(OPh)(3)}, (c) (CO)(PBu3n), (d) (CNMe)(2) and (e) (CNMes)(2) (Mes = 2,4,6-Me3C6H2), but not (CO)(CNMes), react with CS2 under reflux to give [Co(eta(5)-C5H5)}(2){Fe(L)(2)}(mu(3)-S)(mu(3)-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(eta(5)-C5H5)}(2){Fe(L)(2)}(mu(3)-S)(mu(3)-C2S3E] adducts which contain S*-->E bonds where E = Me+ [3](+), Et+ [4](+), HgCl2 [5], and I-4 (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 . 2C(6)H(6) and [3a] I . C6H6 . CHCl3 are reported. Cluster 2a contains a very short Fe - C-mu bond as compared with 1a, and it is suggested that in many respects the FeSC(S)SCmu ring is best regarded as a metallo-1,3-dithiole-2-thione (or metallovinyl trithiocarbonate) with a Fe-C-mu double bond which, on alkylation at the exocyclic S*, adopts a more delocalised electronic structure with a longer Fe - C-mu bond. Spectroscopic and electrochemical data for the new compounds are discussed.