Reaction of lithium ethynethiolate or ethyneselenolate, LiX'CrCPh (Xl = S or Se), with carbene complexes [M(CO),{C(OR1)Ph}] (M = Cr or W; R1 = M e or Et) afforded, by the formation of carbon-carbon bonds, a series of adducts, Li[M (CO),{C(OR') PhC( Ph)=C=X'}]. The adducts reacted regioselectively with electrophiles: acidification with HCI gave a,p-unsaturated thio-and seleno-aldehyde complexes, [M(CO),{X'=CHC(Ph)=C(OR') Ph}], alkylating agents [Et,O] [BF,] or Me1 gave a,P-unsaturated thio-or seleno-carbene complexes, [M (CO),{C(X1R3) -C( Ph)=C(OR') Ph] (X1R3=SEt, SMe, or SeEt), which cleanly and spontaneously converted into sulphur-or selenium-co-ordinated indene derivatives, [M(CO),{(X1R3)CH(C,H,-0)-C(OR1)=CPh}] (X'R3=SEt or SeEt), and, finally, disulphides R4SSR4( R4=Me, Et, or Ph) or the diselenide PhSeSePh yielded thio-or seleno-ester complexes[ M (CO),{X1 =C(XZR4)C( Ph)= C( OR') Ph] (XZR4=SMe, SEt, SPh, or SePh). Four X-ray crystal-structure determinations established the stereochemical configurations of selected members of the various classes of acyclic products.The isomeric compound to one of the thioaldehyde complexes, [W( CO),{S=C( Ph)CH=C(OEt) Ph}], obtained from the adducts with X = S or Se and R' = Et on acidification in the presence of CS, or CSe,, was also characterized structurally by single-crystal X-ray diffraction.
