This paper reports (i) a rational synthesis of heterometallic
sulfide clusters with M−S−M‘ (M and M‘ = Rh, W,
and Cu) groups, (ii) structures and bonding of the M−S−M‘ groups
determined by X-ray crystallographic analysis
and IR spectroscopy, and (iii) reactivity of the M−S−M‘ groups
unique to higher-nuclearity heterometallic sulfide
clusters toward H2O and H2S. A
branched-type octanuclear sulfide cluster
[{Cp*RhP(OEt)3(μ-WS4)(CuCl)Cu}2(μ-Cl)2] (4, Cp* =
η5-C5Me5) was stepwise
prepared from the following sequence:
[Cp*RhP(OEt)3Cl2]
(1,
mononuclear) → [Cp*RhP(OEt)3WS4]
(2, dinuclear) →
[Cp*RhP(OEt)3(μ-WS4)CuCl]
(3, linear-type trinuclear)
→ 4 by a systematic building-block method. A bridging
sulfide ligand in the W−S−Cu group of 4 reacts
with
a water-saturated CH2Cl2 solution to
convert the terminal O atom of
[{Cp*RhP(OEt)3(μ-WOS3)(CuCl)Cu}2(μ-Cl)2] (5, linked incomplete cubane-type
octanuclear) with a drastic structural change in the cluster
framework.
The transformation reaction of 4 to 5
includes the first example of the conversion of the bridging S atom in
the
M−S−M‘ group into the terminal O atom without releasing the metal
atoms, and this reaction is peculiar to the
higher-nuclearity heterometallic sulfide cluster 4.
Clusters 4, 5, and 6
([Cp*RhP(OEt)3(μ-WOS3)CuCl],
butterfly-type trinuclear) react with H2S in
CH2Cl2 giving 3 as a major
product. The formation of 3 in these reactions
are
based on the reactivity of M−S−Cu groups in the sulfide clusters
toward H2S: the (μ3-S)−Cu bonds are
easily
broken by H2S, but not the (μ2-S)−Cu ones.
The crystal data for 1, 2, 3,
4, 5, and 6 confirmed by X-ray
analysis
are as follows. 1:
C16H30Cl2O3PRh,
orthorhombic, P21
cn, a =
8.988(3) Å, b = 28.591(5) Å, c =
8.276(3) Å,
Z = 4. 2:
C16H30O3PRhS4W,
monoclinic, P21/n, a =
14.633(2) Å, b = 15.191(2) Å, c =
11.490(1) Å, β =
104.97(1)°, Z = 4. 3:
C16H30ClCuO3PRhS4W,
monoclinic, P21/m, a =
10.221(2) Å, b = 11.943(2) Å, c
=
10.809(1) Å, β = 94.40(1)°, Z = 2.
4:
C32H60Cl4Cu4O6P2Rh2S8W2,
monoclinic, P21/n, a =
10.170(3) Å, b =
14.495(3) Å, c = 19.411(3) Å, β =
104.42(1)°, Z = 2. 5·2DMF:
C38H74Cl4Cu4N2O10P2Rh2S6W2,
monoclinic,
P21/c, a =
10.011(3) Å, b = 17.115(3) Å, c =
18.678(3) Å, β = 95.10(2)°, Z = 2.
6:
C16H30ClCuO4PRhS3W,
orthorhombic, P21
nb, a =
14.515(2) Å, b = 17.225(3) Å, c =
10.261(3) Å, Z = 4.
