The title clusters, several examples of which have been reportedearlier, have been prepared by two differentmethods and subjected to structural and reactivity studies. Thecompounds(Et
4N)
3[(OC)
3MFe
3S
4(Smes)
3]·MeCN(M = Mo/W) are isomorphous and crystallize in monoclinic space
group
P2
1/
n with
a =13.412(1)/13.297(1) &Arin
g;,
b = 19.0380(1)/18.9376(3) &Arin
g;,
c =26.4210(1)/26.2949(1) &Arin
g;,
![](/ima<font color=)
ges/
gifchars/beta2.
gif" BORDER=0 ALIGN="middle"> =97.87(1)/97.549(1)
![](/ima<font color=)
ges/entities/de
g.
gif">, and
Z = 4. Theclusterscontain lon
g M-S (2.62/2.59 &Arin
g;) and M-Fe (3.22/3.19 &Arin
g;) bonds,consistent with the reported structure of[(OC)
3MoFe
3S
4(SEt)
3]
3-(
3). Reaction of[(OC)
3MoFe
3S
4(LS
3)]
3-(
7) with CO in the presence of NaPF
6affordscuboidal[Fe
3S
4(LS
3)]
3-(
9), also prepared in this laboratory by another route as asynthetic analo
gue of protein-bound [Fe
3S
4]
0 clusters. Theclusters[Fe
3S
4(SR)
3]
3-(R = mes, Et), of limited stability, were
generated bythesame reaction. Treatment of
9 with[M(CO)
3(MeCN)
3] affords
7 andits M = W analo
gue. The clusters[(OC)
3MFe
3S
4(SR)
3]
3-form a four-member electron transfer series in which the 3- clustercan be once reduced(4-) and twice oxidized (2-, 1-) to afford clusters of theindicated char
ges. The correct assi
gnment of redoxcouple to potential in the redox series of six clusters is presented,correctin
g an earlier misassi
gnment of theredox series of
3. Carbonyl stretchin
g frequencies areshown to be sensitive to cluster oxidation state, showin
gthat the M sites and Fe
3S
4 fra
gments areelectronically coupled despite the lon
g bond distances.(LS
3 = 1,3,5-tris((4,6-dimethyl-3-mercaptophenyl)thio)-2,4,6-tris(
p-tolylthio)benzenate(3-);mes = mesityl.)