The reactio
n of the di
nuclear peroxotu
ngstate, [(
n-C
4H
9)
4N]
2[{WO(O
2)
2}
2(<
IMG SRC="/images/e
ntities/mgr.gif">-O)] (
II), with H
2O
2 gives the
novel
ntities/mgr.gif">-
1:
1-peroxo-bridgi
ng di
nuclear tu
ngste
n species, [(
n-C
4H
9)
4N]
2[{WO(O
2)
2}
2(
ntities/mgr.gif">-O
2)] (
I), which has bee
n characterizedby X-ray crystallography, eleme
ntal a
nalysis, IR, Rama
n, UV-vis, a
nd
183W NMR. O
nly
I is active for the epoxidatio
nof cyclic, i
nter
nal, a
nd termi
nal
olefi
ns, whereas
II is i
nactive for each. The low
XSO (
XSO = (
nucleophilic oxidatio
n)/(total oxidatio
n)) value of
I (0.18 ± 0.02) i
n compariso
n with that of
II (0.39 ± 0.01) for the stoichiometric oxidatio
nof thia
nthre
ne 5-oxide, which is a mecha
nistic probe for determi
ni
ng the electro
nic character of a
n oxida
nt, revealsthat
I is more electrophilic tha
n II. O
n the basis of the ki
netic a
nd spectroscopic results, the catalytic epoxidatio
nproceeds by the reactio
n of
I with a
n olefi
n to form
II a
nd the correspo
ndi
ng epoxide followed by the rege
neratio
nof
I by the reactio
n of
II with H
2O
2.