Insertion of phenylethyne-thiolate or -selenolate into metal–carbene bonds: synthons for co-ordinated thioacyl or selenoacyl anions and for anionic thiocarbene or selenocarbene complexest

Reaction of lithium ethynethiolate or ethyneselenolate, LiX1CCPh (X1= S or Se), with carbene complexes [M(CO)5{C(OR1)Ph}](M = Cr or W; R1= Me or Et) afforded, by the formation of carbon-carbon bonds, a series of adducts, Li[M(CO)5{C(OR1)PhC(Ph)CX1}]. The adducts reacted regioselectively with electrophiles: acidification with HCl gave α,β-unsaturated thio- and seleno-aldehyde complexes, [M(CO)5{X1CHC(Ph)C(OR1)Ph}], alkylating agents [Et3O][BF4] or Mel gave α,β-unsaturated thio-or seleno-carbene complexes, [M(CO)5{C(X1R3)-C(Ph)C(OR1)Ph](X1R3SEt, SMe, or SeEt), which cleanly and spontaneously converted into sulphur- or selenium-co-ordinated indene derivatives, [M(CO)5{(X1R3)CH(C6H4-o)-C(OR1)CPh}](X1R3SEt or SeEt), and, finally, disulphides R4SSR4(R4Me, Et, or Ph) or the diselenide PhSeSePh yielded thio- or seleno-ester complexes[M(CO)5{X1C(X2R4)C(Ph)C(OR1)Ph](X2R4SMe, 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)5{SC(Ph)CHC(OEt)Ph}], obtained from the adducts with X = S or Se and R1= Et on acidification in the presence of CS2 or CSe2, was also characterized structurally by single-crystal X-ray diffraction.