Abstract
The hydration of unactivated alkynes represents an important
method of functionalizing this plentiful hydrocarbon resource and
has found considerable synthetic use.1 Transition metals are
widely used to catalyze this process as well as the analogous
reaction in which alcohols are added across the triple bond.2
Though -vinyl ether3 and -vinyl alcohol3,4 complexes are un-
doubtedly intermediates in these reactions, to our knowledge there
have been no reports of such species resulting from an ^-coor-
dinated alkyne. In an early paper on the reactivity of ?;2-alkyne
complexes of platinum(II), Chisholm and Clark suggested that
addition of methanol occurred across the alkyne bond to produce
a vinyl ether intermediate, but this suggestion was later with-
drawn.5 Here we report that the alkyne complex [Os(NH3)5-
(p2-CH3CCCH3)]2+ reacts quantitatively with methanol or water
to form -vinyl ether and -vinyl alcohol complexes, respectively.
Reduction of the precursor Os(NH3)5(OTf)3 (OTf= CF3S03")
in the presence of 2-butyne results in a complex, 1, which is readily
characterized as [Os(NH3)5(p2-CH3CCCH3)](OTf)2.6 Though
the thermal instability of this material has precluded a successful
microanalysis,7 convincing evidence for this assignment is provided.....
