Organothiometallate - alkyne addition products. The crystal and molecular structure of [(η5-C5H5)W{C(CO2Me)C(CO2Me)C(O)SMe} (CO)2]

The title compound is the final product of the reaction between dimethylacetylene dicarboxylate and (η⁵-C₅H₅)W(SMe) (CO)₃ ]. Its molecular structure has been established by an $\text{x}$-ray analysis based on 3301 diffractometric intensities. The crystals are monoclinic, space group $\text{P}$2₁/$\text{a}$, with four molecules in a cell of dimensions $\text{a}$ = 10.323(2), $\text{b}$ = 16.016(2), $\text{c}$ = 10.437(2)», β = 103.56(2)°. After least-squares refinement $\text{R}$ = 0.036. The tungsten co-ordination is square-pyramidal, the apical site being occupied by the centroid of the cyclopentadienyl ring. The basal co-ordination sites contain two carbonyl groups and also the sulphur and σ-bonded carbon atoms of a chelating carbothiolic methyl ester ligand derived from the incoming alkyne and CO and SMe groups of the original complex. The W-S and σ-W-C bond lengths are 2.440(2) and 2.194(7)».