Co-ordinatively unsaturated molybdenum and tungsten acetylene complexes. The mechanisms of formation of and CO substitution in [M(η⁵- C₅H₅)(SR)(CO)(CF₃C⋮CCF₃]

Reactions between [M(?⁵-C₅H₅)SR ¹(CO)₃] (M = W; R¹ = Me, Et, or Prⁱ) and hexafluorobut-2-yne (hfb) involve initial attack at sulphur and carbonyl ligands to give [[graphic omitted]R¹)(?⁵-C ₅H₅)(CO)₂] which undergo stepwise rearrangement to co-ordinatively unsaturated acetylene complexes [M(?⁵-C ₅H₅)(SR¹)(CO)(hfb)]; the latter (M = Mo or W, R¹ = C₆F₅) undergo associative CO substitution reactions with phosphines and phosphites (L) yielding complexes [M(?⁵-C₅H₅)(SR¹)(hfb)L].