Synthesis and structural characterization of Mo2(μ-SC6H4-Cl-p) 2(μ-dppm)(CO)6 and [(dppm)(CO)2Mo(μ-SC6H4-Cl-p) 2Mo(O)]2(μ-SC6H4-Cl-p) 2(μ-O) and electrochemical property of Mo2(μ-SC6H4-Cl-p) 2

Article abstract of DOI:10.1016/S0022-328X(98)01168-1

Dimolybdenum(I) compound Mo₂(μ-SC₆H₄-Cl-p)₂(|.i-dppm)(CO)6 (1), (dppm = (C₆H₅)₂PCH₂P(C₆H ₅)₂), and a trace unexpected mixed-valence tetranuclear molybdenum compound [(dppm)(CO)₂Mo(μ-SC₆H₄-Cl-p) ₂Mo(O)]₂(μ-SC₆H₄-Cl-p) ₂(μ-O) (2) were obtained from the reaction of Mo₂(μ-SC₆H₄-Cl-p)₂(CO)8 with dppm in CH₂Cl₂. The crystal structures of the two compounds have been determined by X-ray diffraction studies. 1: monoclinic, P2(1)/n, a = 13.1082(3), b = 23.9584(4), c = 14.8510(2) A, β = 105.865(1)°, V = 4486.32(14) A3, Z = 4, 9859 unique data, R₁ = 0.0805, wR₂ = 0.1076. 2·CH₂Cl₂: monoclinic, C2/c, a = 22.0955(13), b = 19.1563(11), c = 25.1981(14) A, β = 112.243(1)°, V = 9871.9(1) A³, Z = 4, 7053 unique data, R₁ = 0.0450, wR₂ = 0.1222. The cyclic voltammetry (CV) measurement for 1 showed a reversible two-electron transfer in a single step.

Full text of DOI:10.1016/S0022-328X(98)01168-1

Journal of Organometallic Chemistry 580 (1999) 313–319
Synthesis and structural characterization of
Mo2(m-SC6H4–Cl-p)2(m-dppm)(CO)6 and
[(dppm)(CO)2Mo(m-SC6H4–Cl-p)2Mo(O)]2(m-SC6H4–Cl-p)2(m-O) and
electrochemical property of Mo2(m-SC6H4–Cl-p)2(m-dppm)(CO)6
Guohua Pan, Botao Zhuang *, Lingjie He, Jiutong Chen, Jiaxi Lu
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou,
Fujian 350002, PR China
Received 28 September 1998
Abstract
Dimolybdenum(I) compound Mo2(m-SC6H4–Cl-p)2(m-dppm)(CO)6 (1), (dppm=(C6H5)2PCH2P(C6H5)2), and a trace unex-
pected mixed-valence tetranuclear molybdenum compound [(dppm)(CO)2Mo(m-SC6H4–Cl-p)2Mo(O)]2(m-SC6H4–Cl-p)2(m-O) (2)
were obtained from the reaction of Mo2(m-SC6H4–Cl-p)2(CO)8 with dppm in CH2Cl2. The crystal structures of the two
compounds have been determined by X-ray diffraction studies. 1: monoclinic, P2(1)/n, a=13.1082(3), b=23.9584(4), c=
3
˚
˚
14.8510(2) A, i=105.865(1)°, V=4486.32(14) A , Z=4, 9859 unique data, R1=0.0805, wR2=0.1076. 2·CH2Cl2: monoclinic,
3
˚
˚
C2/c, a=22.0955(13), b=19.1563(11), c=25.1981(14) A, i=112.243(1)°, V=9871.9(1) A , Z=4, 7053 unique data, R1=
0.0450, wR2=0.1222. The cyclic voltammetry (CV) measurement for 1 showed a reversible two-electron transfer in a single step.
© 1999 Elsevier Science S.A. All rights reserved.
Keywords: Molybdenum; Mo2S2 unit; Crystal structure; Electrochemistry
were mainly focused on Mo(0) atom, however, less
Mo(I) compounds were systematically investigated.
1. Introduction
More recently, an attempt to further develop studies on
synthesis, structure and physical and chemical proper-
ties of rare Mo(I) carbonyl thiolate compound has been
carried out in this research group. By reaction of
Mo2(m-SC6H4–Cl-p)2(CO)8 with dppm, a new dinuclear
molybdenum(I) carbonyl thiolate compound with a
diphosphine bridging ligand Mo2(m-SC6H4–Cl-p)2(m-
dppm)(CO)6 (1) and a by-product [(dppm)(CO)2Mo(m-
SC6H4–Cl-p)2Mo(O)]2(m-SC6H4–Cl-p)2(m-O) (2) have
been obtained and investigated. Herein, we report the
synthesis and structural characterization of 1 and 2,
and electrochemical behavior of 1.
We are continuously interested in the research on
low-valence dinuclear molybdenum carbonyl thiolate
compounds [Mo2(m-SR)2(CO)8]2−,0 (R=Ph [1,2],
CH2CO2Et [3], o-H3C–C6H4 [4]), because they possess
an interesting two-electron transfer character in a single
step when containing a planar Mo2S2 unit and lose this
electrochemical feature when containing a butterfly
type Mo2S2 core [4]. Studies on this kind of compound
* Corresponding author. Fax: +86-0591-3714946.
E-mail address: zbt@ms.fjirsm.ac.cn (B. Zhuang)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01168-1

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G. Pan et al. / Journal of Organometallic Chemistry 580 (1999) 313–319
2. Results and discussion
2.1. Syntheses and characterization
Reaction of Mo2(m-SC6H4–Cl-p)2(CO)8 with dppm
in dichloromethane yielded dinuclear compound,
Mo2(m-SC6H4–Cl-p)2(m-dppm)(CO)6 (1), and a trace of
tetranuclear compound, [(dppm)(CO)2Mo(m-SC6H4–
Cl-p)2Mo(O)]2(m-SC6H4–Cl-p)2(m-O) (2), which were
separated as red crystals under a microscope. But reac-
tion of Mo2(m-SC6H4–Cl-p)2(CO)8 with Bu4NBr and
then dppm in acetone only afforded compound 1 in
high yield. The compound 1 has been characterized by
spectroscopies and elemental analysis.
The IR spectrum of 1 exhibited five w(CO) bands at
Fig. 1. A view of a molecule of 1 with 30% probability ellipsoids. The
phenyl rings of dppm are omitted.
1
2010, 1963, 1934, 1917, 1884 cm−1. The H-NMR and
13C-NMR spectra of 1 showed peaks at 2.9 and 55.1
ppm, respectively, which were attributed to CH2 in
P–CH2–P of dppm, indicating dppm coordinating to
the parent compound Mo2(m-SC6H4–Cl-p)2(CO)8. The
only 31P-NMR peak at 18.4 ppm observed for 1 indi-
cated each P atom coordinating to central metal atom
is in identical electron structure and coordination envi-
ronment. Likewise, the only 95Mo-NMR peak at −936
ppm also indicated that the electronic structure and the
space structure of the two molybdenum atoms are
identical. The 95Mo-NMR chemical shift of compound
1 is more downfield than that of Mo2(m-SC6H4–Cl-
p)2(CO)8 (−1100 ppm), indicating that coordination of
dppm leads to more deshielding than that of CO. This
is consistent with the results: in general substitution of
a CO group in Mo(CO)6 by a weaker p-acceptor than
CO leads to deshielding relative to Mo(CO)6, reported
by Minelli et al. [5]. It seems that this result is contrary
to the general idea that substituting CO by dppm
should lead to increasing electron density on metal
atom, but considering the chemical shift–oxidation
state relationship that holds in the di- and tri-nuclear
Mo–W-series complexes with an M–M bond: the
shielding increases (NMR signal shift to upfield) with
an increase in oxidation state [6,7] this result is compre-
hensible. The compound 2 was characterized by mea-
surement of IR and 31P-NMR spectra because only a
few single crystals were obtained. The IR spectrum of 2
2.2. Crystal structures
2.2.1. The structure of 1
The structure of 1 is shown in Fig. 1. Selected bond
lengths and bond angles are listed in Table 1. The
molecule of 1 consists of two fac-Mo(CO)3 fragments
linked by an Mo–Mo bond, two p-chrolo-phenylthio-
late bridging groups and a bidentate bridging dppm
ligand. The geometry of each Mo atom is distorted
octahedron with 3C, 1P, and 2S. The distortion is due
to the large SMoS angle of 105.70(3)°. Two bridging S
atoms and two carbonyl groups form an equatorial
plane, the other carbonyl and the P atom of dppm
ligand occupy the axial position of each Mo atom. The
whole structure could be considered as an edge-sharing
bioctahedral structure consisting of two distorted octa-
hedrons with central Mo atoms in which the Mo–Mo
˚
bond length is 2.9946(10) A, indicating the metal–metal
Table 1
˚
Selected bond lengths(A) and angles (°) for 1
Mo(1)–C(3)
Mo(1)–C(2)
Mo(1)–C(1)
Mo(1)–S(2)
Mo(1)–S(1)
Mo(1)–P(1)
Mo(1)–Mo(2)
Mo(2)–C(6)
Mo(2)–C(5)
1.989(10)
2.003(10) Mo(2)–S(2)
Mo(2)–C(4)
2.026(10)
2.484(2)
2.491(2)
2.571(3)
1.144(8)
1.149(9)
1.150(10)
1.126(9)
1.151(9)
1.147(11)
2.006(9)
2.459(2)
2.499(2)
2.563(2)
2.9946(10) C(3)–O(3)
1.972(12) C(4)–O(4)
2.000(10) C(5)–O(5)
C(6)–O(6)
Mo(2)–S(1)
Mo(2)–P(2)
C(1)–O(1)
C(2)–O(2)
showed two w(CO) bands at 1888 and 1869 cm−1
,
which had a red shift relative to that of 1; this might be
attributed to the increase of metal–CO back-donating
when a P atom replaces CO. In addition, the absorp-
tion at 910 cm−1 is characteristic of terminal MoꢀO
and the peak at 748 cm−1 should be the vibration of
Mo–O–Mo [8]. The only 31P-NMR at 9.7 ppm of 2 is
more upfield than that of 1, indicating the different
coordinating pattern of dppm between 1 and 2. In fact,
as shown in below structure analyses, the coordinating
mode of dppm in 1 and 2 are interbridging and chelat-
ing, respectively [9].
S(2)–Mo(1)–S(1)
S(2)–Mo(1)–P(1)
S(1)–Mo(1)–P(1)
S(2)–Mo(1)–Mo(2)
S(1)–Mo(1)–Mo(2)
P(1)–Mo(1)–Mo(2)
S(2)–Mo(2)–S(1)
S(2)–Mo(2)–P(2)
105.96(7)
S(1)–Mo(2)–P(2)
90.32(7)
52.34(5)
53.25(5)
90.00(5)
73.75(6)
74.57(6)
111.4(4)
81.62(7)
95.13(7)
53.10(5)
53.00(5)
90.57(5)
105.44(7)
85.76(8)
S(2)–Mo(2)–Mo(1)
S(1)–Mo(2)–Mo(1)
P(2)–Mo(2)–Mo(1)
Mo(2)–S(1)–Mo(1)
Mo(1)–S(2)–Mo(2)
P(2)–C–P(1)

G. Pan et al. / Journal of Organometallic Chemistry 580 (1999) 313–319
315
Mo2S2 plane. This is due to the great hindrance of dppm
ligand. The axial Mo–C (trans to dppm) (mean 1.980(10)
˚
A) is slightly shorter than the equatorial Mo–C (trans
˚
to S bridging) (mean 2.009(10) A) because of the trans-
effect of dppm and p-chrolophenylthiolato ligand. The
shorter axial Mo–C length and the steric hindrance from
the syn orientation of p-chrolophenylthiolato ligands
imply a difficulty to obtain four-bridge compound,
Mo2(m-SC6H4–Cl-p)2(m-dppm)2(CO)4. P–Mo–Mo an-
gle is near 90°, P–C–P angle is 111.4(4)°, the span of two
P atoms of dppm is just matching the Mo–Mo bond
length. It is obvious that 1 forms via a substitution of a
dppm for the two axial carbonyl groups which are on the
same side with respect to Mo2S2 plane in the parent
compound Mo2(m-SC6H4–Cl-p)2(m-dppm)(CO)6.
2.2.2. The structure of 2
The structure of 2 is shown in Fig. 2. Selected bond
lengths and angles are listed in Table 2. The molecule of
2 can be viewed as the structure that two species
[(dppm)(CO)2Mo(m-SC6H4–Cl-p)2Mo(O)] linked by two
bridging SC6H4–Cl-p and one bridging oxo, or two
fragments [(dppm)(CO)2Mo(m-SC6H4–Cl-p)2] connected
with (O)Mo(m-SC6H4–Cl-p)2(m-O)Mo(O) core. A c2 axis
is passing through the bridging oxygen atom, and the
carbon atom of solvent molecule CH2Cl2 is also located
on this axis.
Fig. 2. A view of a molecule of 2 with 30% probability ellipsoids. The
phenyl rings of dppm are omitted.
interaction that results from the coupling of the unpaired
spins of two Mo(I) ions (d5). The bond distance of
˚
Mo(1)–S(1) (2.499(2) A) is slightly longer than that of
˚
Mo(1)–S(2)(2.459(2) A). The Mo2S2 unit is planar, and,
in contrast with Mo2(m-SPh)2(CO)8 [10], the two benzene
rings of thiolates are in syn orientation relative to the
Table 2
a
˚
Selected bond lengths (A) and angles (°) for 2·CH2Cl2
Mo(1)–C(2)
Mo(1)–C(1)
Mo(1)–S(1)
Mo(1)–S(2)
Mo(1)–P(2)
Mo(1)–P(1)
Mo(1)–Mo(2)
Mo(2)–O(3)
Mo(2)–O(4)
2.009(6)
2.028(6)
2.407(2)
2.4158(14)
2.500(2)
2.501(2)
2.8570(6)
1.699(4)
1.980(3)
Mo(2)–S(2)
Mo(2)–S(1)
2.4623(14)
2.4623(14)
2.5682(14)
2.5911(14)
2.5682(14)
1.136(7)
1.144(7)
1.980(3)
3.250(3)
Mo(2)–S(3)c1
Mo(2)–S(3)
S(3)–Mo(2)c1
O(1)–C(1)
O(2)–C(2)
O(4)–Mo(2)c1
Mo(2)–Mo(2)c1
S(1)–Mo(1)–S(2)
S(1)–Mo(1)–P(2)
S(2)–Mo(1)–P(2)
S(1)–Mo(1)–P(1)
S(2)–Mo(1)–P(1)
P(2)–Mo(1)–P(1)
S(1)–Mo(1)–Mo(2)
S(2)–Mo(1)–Mo(2)
P(2)–Mo(1)–Mo(2)
P(1)–Mo(1)–Mo(2)
O(3)–Mo(2)–O(4)
O(3)–Mo(2)–S(2)
O(4)–Mo(2)–S(2)
O(3)–Mo(2)–S(1)
O(4)–Mo(2)–S(1)
S(2)–Mo(2)–S(1)
O(3)–Mo(2)–S(3)c1
O(4)–Mo(2)–S(3)c1
S(2)–Mo(2)–S(3)c1
109.72(5)
S(1)–Mo(2)–S(3)c1
O(3)–Mo(2)–S(3)
O(4)–Mo(2)–S(3)
S(2)–Mo(2)–S(3)
S(1)–Mo(2)–S(3)
166.59(5)
154.35(5)
95.26(5)
89.30(5)
157.49(5)
67.79(5)
54.98(3)
54.91(3)
148.64(4)
143.56(4)
159.0(2)
101.96(13)
89.09(8)
93.58(13)
100.45(7)
106.41(5)
89.89(13)
73.03(9)
85.48(4)
94.18(13)
72.49(9)
160.95(5)
82.34(5)
84.49(5)
99.50(12)
101.44(12)
53.40(3)
53.17(4)
138.83(4)
133.89(4)
71.85(4)
71.69(4)
109.7(2)
119.9(2)
78.15(4)
110.4(2)
98.8(3)
S(3)c1–Mo(2)–S(3)
O(3)–Mo(2)–Mo(1)
O(4)–Mo(2)–Mo(1)
S(2)–Mo(2)–Mo(1)
S(1)–Mo(2)–Mo(1)
S(3)c1–Mo(2)–Mo(1)
S(3)–Mo(2)–Mo(1)
Mo(1)–S(1)–Mo(2)
Mo(1)–S(2)–Mo(2)
C(31)–S(3)–Mo(2)c1
C(31)–S(3)–Mo(2)
Mo(2)c1–S(3)–Mo(2)
Mo(2)c1–O(4)–Mo(2)
P(2)–C(0)–P(1)
a Symmetry transformations used to generate equivalent atoms:
c1, −x+1, y, −z+1/2; c2, −x, y, −z+1/2.

316
G. Pan et al. / Journal of Organometallic Chemistry 580 (1999) 313–319
that of 1, due to the high oxidation state of Mo(2). The
metal–metal bonding resulted from the coupling of the
unpaired spins of one Mo(I) and one Mo(V) (d1–d5).
˚
The Mo(2)–Mo(2c) distance is 3.250(3) A, indicating
no metal–metal interaction between Mo(2) and
Mo(2c). Because of dppm trans-effect, both Mo(1)–
S(1) and Mo(1)–S(2) become shorter than those of 1; in
˚
˚
addition, Mo(1)–S(1) (2.407(2) A) is ca. 0.01 A shorter
˚
than Mo(1)–S(2) (2.4158(14) A). Mo(2)ꢀO bond length
(1.699(4) A) and Mo(2)–O(4) (1.980(3) A) are in the
normal ranges [8,11].
˚
˚
Fig. 3. Cyclic voltammograms of 1, recorded in acetone; concentra-
tion, 0.0002 M; scan rate, 100 mV s−1
.
The formation mechanism of the tetranuclear oxo-
product [(dppm)(CO)2Mo(m-SC6H4–Cl-p)2Mo(O)]2(m-
SC6H4–Cl-p)2(m-O) (2) could not be ascertained, but we
assume that the trace oxygen comes from an unex-
pected leakage in the course of experiment. In fact, the
oxidation of Mo(2) atom from +1 to +5 also could
manifest this phenomenon. However, the addition of
air to the reaction mixture does not improve the yield
of 2 significantly implying that the formation of 2 dose
not come from the oxidation of 1 and, however, the
presence of dioxygen leads to extensive degradation of
1 and complicated oxo-products.
In the half of the structure of 2, the coordination
environments and the oxidation states of two Mo
atoms are different. The Mo(1) atom, in +1 oxidation
state, is located in a distorted octahedron with 2P, 2S
and 2CO groups, having a large S(1)Mo(1)S(2) angle
(109.72(5)°) and small P(1)Mo(1)P(2) angle (67.79(5)°).
˚
˚
Mo(1)–C(1) (2.028(6) A) is 0.02 A longer than Mo(1)–
˚
C(2) (2.009(6) A). The PCP angle is 98.8(3)°. The dppm
acts as a chelate ligand in accordance with the datum
observed on 31P-NMR. But the Mo(2) atom, in +5
oxidation state, is in six coordination with 2O and 4S,
of which the geometry of Mo(2) atom cannot be de-
scribed in terms of simple symmetry. Mo(1), Mo(2),
S(1), and S(2) atoms are coplanar. Relative to the
Mo2S2 plane, two benzene rings of thiolates are in anti
orientation in contrast with that of 1. The Mo(1)–
2.3. Electrochemical beha6ior
The cyclic voltammogram of 1 is depicted in Fig. 3.
Compound 1 displays a reversible redox couple at
−0.63 V (−0.60/−0.66 V vs. SCE) and redox peaks
˚
Mo(2) length of 2.8570(6) A is somewhat shorter than
Table 3
Crystallographic data for 1 and 2·CH2Cl2
Compound
1
2·CH2Cl2
Empirical formula
Formula weight
Crystal system
Space group
C
43H30Cl2Mo2O6P2S2
C91H70Cl8Mo4O7P4S6
2259.07
Monoclinic
C2/c
22.0955(13)
19.1563(11)
25.1981(14)
112.243(1)
9871.9(1), 4
1.520
1031.51
Monoclinic
P2(1)/n
13.1082(3)
23.9584(4)
14.8510(2)
105.865(1)
4486.32(14), 4
1.527
˚
a (A)
˚
b (A)
˚
c (A)
i (°)
3
˚
V (A ), Z
Dcalc. (Mg m−3
)
u (mm−1
)
0.887
0.955
Min/max transmission
F(000)
0.928/0.694
2064
0.943/0.715
4528
Crystal size (mm3)
q range (°)
0.24×0.10×0.10
1.66–25.03
−105h515
−205k528
−175l513
16140
0.20×0.15×0.10
1.49–23.26
−225h524
−215k519
−275l517
18920
Index ranges
Reflections collected
Independent reflections
Data/restraints/parameters
R1, wR2 [I\2|(I)]
R1, wR2 [all data]
7895
7053
7806/0/514
0.0805, 0.1076
0.1823, 0.2367
1.150
7053/0/542
0.0450, 0.1222
0.0575, 0.1333
1.064
Goodness-of-fit
Largest difference peak/hole (e A
−3
˚
)
0.554/−0.707
1.743/−0.462

G. Pan et al. / Journal of Organometallic Chemistry 580 (1999) 313–319
317
A V−1/2 s1/2 cm mol−1, which is nearly double that of
ferrocene (690 A V−1/2 s1/2 cm mol−1) observed under
identical conditions (ferrocene was used as an internal
potential standard). This implies that like the electro-
chemical behavior of [Mo2(SPh)2(CO)8] and its bisubsti-
tuted product, [Mo2(SPh)2(CO)6(MeCN)2] [1,2],
compound 1 undergoes two-electron reversible reduc-
tion in a potential at −0.63V as shown in Eq. (1).
Table 4
Atomic coordinates (×104) and equivalent isotropic displacement
3
˚
parameters (A×10 ) for 1
Atom
x
y
z
Ueq
41(1)
Mo(1)
Mo(2)
S(1)
S(2)
Cl(1)
Cl(2)
P(1)
P(2)
C
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(121)
C(122)
C(123)
C(124)
C(125)
C(126)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(221)
C(222)
C(223)
C(224)
C(225)
C(226)
O(1)
−1175(1)
−2284(1)
−3037(2)
−483(2)
−3873(3)
3413(2)
4067(1)
2966(1)
3904(1)
3147(1)
4348(2)
2126(1)
4108(1)
3048(1)
3431(3)
4883(4)
4298(4)
4075(4)
2157(4)
2639(4)
2864(4)
4014(3)
3640(4)
3744(4)
4232(6)
4611(5)
4499(4)
2890(3)
2893(5)
2654(6)
2435(4)
2468(5)
2712(4)
4344(3)
4014(4)
4218(6)
4758(6)
5092(5)
4890(4)
4568(3)
4729(4)
5072(4)
5258(4)
5100(4)
4768(3)
3353(3)
3488(4)
3717(4)
3813(5)
3686(5)
3450(4)
2364(3)
2075(4)
1535(5)
1281(5)
1561(4)
2094(4)
5347(3)
4419(3)
4104(3)
1705(3)
2421(3)
2780(4)
5480(1)
5043(1)
4518(2)
6091(2)
201(2)
44(1)
42(1)
46(1)
144(2)
102(1)
39(1)
45(1)
46(2)
46(2)
55(3)
50(2)
71(3)
57(3)
62(3)
45(2)
65(3)
76(3)
79(3)
83(3)
63(3)
44(2)
117(5)
111(5)
60(3)
102(4)
81(3)
42(2)
82(3)
121(5)
101(4)
86(4)
67(3)
43(2)
62(3)
77(3)
72(3)
68(3)
52(2)
49(2)
60(3)
81(4)
95(4)
107(4)
81(3)
49(2)
77(3)
110(5)
103(5)
91(4)
69(3)
71(2)
78(2)
81(2)
116(3)
92(3)
115(3)
[Mo2(SC6H4Cl)2(dppm)(CO6)]0
4956(2)
7048(2)
6528(2)
7463(6)
5381(6)
6145(7)
4311(7)
5322(7)
4392(7)
3889(8)
3303(6)
2647(7)
1693(8)
1392(7)
2032(8)
2980(7)
5712(6)
4817(8)
4582(8)
5242(7)
6118(9)
6373(7)
7996(6)
8727(8)
9416(9)
9388(9)
8697(9)
8011(7)
7186(6)
8067(7)
8184(8)
7400(9)
6538(8)
6413(6)
6516(7)
5691(7)
5675(9)
6489(11)
7329(10)
7334(8)
7059(6)
6932(7)
7269(9)
7737(9)
7892(8)
7542(7)
5343(5)
6488(5)
3649(5)
5422(6)
3995(6)
3218(6)
−0.63 V[Mo2(SC6H4Cl)2(dppm)(CO6)]2−
(1)
−1636(2)
−2923(2)
−1988(6)
−1526(7)
308(8)
−713(7)
−1872(8)
−3697(8)
−1838(7)
−3204(7)
−3743(7)
−3951(8)
−3626(9)
−3101(8)
−2892(7)
619(6)
698(9)
1556(9)
2349(7)
2331(8)
1471(8)
−529(6)
15(8)
871(10)
1172(9)
X
2 e
The existence of similar electrochemical behavior be-
tween compound and [Mo2(SPh)2(CO)8] and
1
[Mo2(SPh)2(CO)6(MeCN)2] is reasonable because they
have a common planar M2S2 unit. Similar to the bisub-
stituted product, [Mo2(SPh)2(CO)6(MeCN)2], com-
pound 1 underwent two-electron reversible reduction at
more negative potential than the parent analog
[Mo2(SPh)2(CO)8] (−0.4 V vs. SCE) [1,2] and the
redox couple potential of compound 1 is more positive
than that of [Mo2(SPh)2(CO)6(MeCN)2] (−0.8 V vs.
SCE) [1,2].
The events at more positive potential (0.71 and 0.81
V vs. SCE) were not defined, though it is obvious that
some chemical reaction took place during the electrode
reaction process.
3. Experimental
659(9)
3.1. General procedures
−179(8)
−2700(7)
−2756(7)
−3537(8)
−4311(8)
−4286(7)
−3474(7)
−4210(7)
−4945(8)
−5923(9)
−6150(9)
−5454(10)
−4484(8)
−2971(8)
−3903(8)
−3912(11)
−2985(13)
−2064(10)
−2049(8)
−1746(5)
1176(5)
All reactions were carried out under a nitrogen atmo-
sphere using Schlenk techniques unless noted otherwise.
Solvents were dried and degassed prior to use.
Mo(CO)6, p-Cl–C6H5SH, and dppm were obtained
from Aldrich. Et3N and I2 were purchased from Shang-
hai Chemical Reagent Co. Elemental analyses were
performed on a Carlo Erba MOD 1106. Infrared spec-
tra (KBr pellets) were recorded on a Magna 750. UV-
vis spectra were recorded on a Schimadzu UV-3000
(acetone was used as solvent). 1H-, 13C-, 31P-, and
95Mo-NMR spectra were measured on a Varian Unity-
500 at 499.864, 125.708, 202.364 and 32.544 MHz,
respectively. Proton and carbon chemical shifts are
relative to internal acetone, that of phosphorus is rela-
tive to external aqueous saturated H3PO4 solution, and
molybdenum’s is relative to external aqueous 2 M
Na2MoO4 solution.
O(2)
O(3)
O(4)
O(5)
−422(5)
−1632(6)
−4471(6)
−1591(7)
Cyclic voltammetry (CV) measurements were carried
out on a CV-1B from BAS (Bioanalytical Systems),
using 0.10 M Et4NBF4 as the supporting electrolyte and
acetone as solvent. The working electrode was glassy
carbon (area 0.0804 cm2), the auxiliary electrode was a
platinum wire and the reference electrode was an
O(6)
at 0.81 and 0.71 V versus SCE. The peak current
parameter (ip/V1/2AC) of the event at −0.66 V is 1321

318
G. Pan et al. / Journal of Organometallic Chemistry 580 (1999) 313–319
Table 5
aqueous SCE separated from the sample solution by a
salt bridge containing 0.1 M Et4NBF4 in the solvent.
Solutions were deoxygenated and blanketed with nitro-
gen. As a comparison, ferrocene was measured under
identical conditions (as an internal potential standard).
Atomic coordinates (×104) and equivalent isotropic displacement
2
3
˚
parameters (A ×10 ) for 2·CH2Cl2
Atom
x
y
z
Ueq
36(1)
Mo(1)
Mo(2)
S(1)
S(2)
S(3)
Cl(1)
Cl(2)
Cl(3)
P(1)
P(2)
O(1)
O(2)
O(3)
O(4)
C(0)
C(1)
C(2)
3279(1)
4251(1)
3402(1)
4153(1)
4724(1)
4242(1)
4129(2)
5104(1)
2443(1)
2671(1)
4286(2)
2312(2)
3823(2)
5000
−4220(1)
−3189(1)
−3622(1)
−3886(1)
−2667(1)
−5480(1)
−1891(1)
550(1)
2369(1)
2468(1)
1576(1)
3252(1)
1758(1)
−77(1)
5214(1)
1532(1)
1674(1)
2839(1)
2508(2)
2323(2)
2485(2)
2500
E1/2= +0.48 V (vs. SCE) for the ferrocene–ferroce-
34(1)
42(1)
38(1)
38(1)
111(1)
124(1)
100(1)
44(1)
45(1)
71(1)
68(1)
43(1)
35(1)
54(2)
45(1)
45(1)
48(1)
72(2)
89(3)
74(2)
67(2)
56(2)
41(1)
66(2)
83(2)
71(2)
64(2)
50(2)
43(1)
63(2)
72(2)
60(2)
55(2)
48(1)
55(2)
118(4)
182(7)
158(6)
111(3)
79(2)
48(2)
68(2)
83(2)
89(3)
85(2)
67(2)
56(2)
79(2)
106(3)
126(4)
116(4)
78(2)
58(2)
105(3)
148(5)
136(6)
111(4)
83(2)
252(3)
155(8)
nium couple. The concentration of the sample com-
pounds in these measurements was 10−3 M, the scan
rate was 100 mV s−1
.
[Mo2(m-SC6H4–Cl-p)2(CO)8] was prepared referring
to the literature method [1,2].
−4998(1)
−4926(1)
−5447(3)
−2990(3)
−2458(2)
−3779(2)
−5251(3)
−5004(3)
−3440(3)
−4118(3)
−4056(4)
−4465(5)
−4925(4)
−4974(4)
−4564(4)
−3308(3)
−2982(4)
−2552(4)
−2441(4)
−2752(4)
−3188(3)
−1747(3)
−1273(3)
−563(3)
3.2. Syntheses of complexes 1 and 2
(A) A sample of Mo2(m-SC6H4–Cl-p)2(CO)8 (0.705 g,
1 mmol) was dissolved in 30 ml of acetone resulting in
green solution. To this green solution was added one
equivalent Bu4NBr (0.322 g, 1 mmol), the solution
immediately turned brown, accompanied by a vigorous
CO evolution. After 1 h of stirring, to the resulting
solution was added one equivalent dppm (0.384 g, 1
mmol). After stirring overnight, the reaction solution
was evaporated to 10 ml under vacuum and 20 ml of
isopropanol was added, then this solution was filtered
and the filtrate was allowed to stand at −4°C for
several days. A black crystalline product 1 (0.72 g, yield
ca. 70%) formed and was collected by filtration, washed
with isopropanol, and dried in vacuum. Anal. Found:
C, 49.60; H, 2.81. Anal. Calc. for C43H30Cl2Mo2O6P2S2:
C, 50.07; H, 2.93%; IR (KBr pellet): w(CO) 2010(s),
2049(3)
3922(3)
2658(3)
3716(3)
3385(4)
3552(5)
4054(4)
4412(3)
4244(3)
4090(3)
3529(3)
3539(4)
4109(4)
4682(4)
4663(3)
4817(3)
4410(3)
4497(4)
4974(3)
5374(3)
5296(3)
1792(3)
1653(5)
1141(6)
777(6)
2169(3)
2440(3)
2337(2)
1138(2)
556(3)
177(3)
385(3)
963(3)
1342(3)
3778(2)
3764(3)
4207(3)
4653(3)
4687(3)
4245(2)
1725(2)
1838(3)
1779(4)
1602(3)
1476(3)
1539(3)
1016(3)
928(4)
456(5)
50(5)
120(4)
602(3)
1471(3)
1001(3)
857(4)
1192(4)
1660(4)
1804(3)
3269(3)
3308(3)
3643(5)
3949(5)
3911(4)
3572(3)
3230(3)
3798(4)
4113(6)
3834(7)
3263(6)
2949(4)
2017(3)
2500
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
C(51)
C(52)
C(53)
C(54)
C(55)
C(56)
C(61)
C(62)
C(63)
C(64)
C(65)
C(66)
C(71)
C(72)
C(73)
C(74)
C(75)
C(76)
Cl
1
1963(s), 1934(s), 1917(s) and 1884(s) cm−1; H-NMR
(CD3COCD3): l 2.9(d, 2H, P–CH2–P) and 7.3–7.9 (m,
30H, SPh and PPh2) ppm; 13C-NMR (CD3COCD3): l
232.2 (2CO, trans to P atom), 227.6 (4CO, cis to P
atom), 136.4–129.4 (36C, SPh and PPh2) and 55.1 (1C,
P–CH2–P); 31P-NMR (CD3COCD3): l 18.4 ppm;
95Mo-NMR (CD3COCD3): l −937 ppm and UV-vis
(CD3COCD3): umax 444, 326 and 314 nm.
−340(3)
−805(3)
−1511(3)
−4714(3)
−4019(5)
−3792(6)
−4266(6)
−4940(5)
−5172(4)
−5799(3)
−5800(4)
−6369(4)
−6961(4)
−6978(4)
−6397(4)
−5693(3)
−6232(4)
−6801(5)
−6844(5)
−6321(5)
−5743(4)
−4511(3)
−4530(5)
−4211(7)
−3876(6)
−3828(4)
−4144(4)
−2465(3)
−1962(9)
916(5)
(B) To
a green solution of Mo2(m-SC6H4–Cl-
1417(4)
2745(3)
2923(4)
3204(4)
3309(4)
3141(4)
2856(4)
3012(3)
2600(4)
2854(6)
3500(7)
3920(5)
3663(4)
2219(3)
2457(5)
2131(9)
1580(8)
1332(5)
1655(4)
172(3)
p)2(CO)8 (0.705 g, 1 mmol) in 30 ml of dichloro-
methane was added dppm (0.384 g, 1 mmol), and the
solution gradually turned red–brown, accompanied by
a CO evolution. After stirred overnight, the resulting
solution was treated by the same way as in (A). 1 and
an unexpected trace of red 2·CH2Cl2 were obtained,
and the trace 2·CH2Cl2 as red crystals were separated
from 1 by using a microscope in air. IR (KBr pellet):
w(CO) 1888(s) and 1869(s); w(MoOMo), 748(m) and
w(MoꢀO), 910(m) cm−1 31P-NMR (CD3COCD3): l 9.7
.
ppm.
3.3. X-ray crystallography
The crystals of 1 and 2·CH2Cl2 were grown in ace-
tone/isopropanol and CH2Cl2/isopropanol mixed sol-
vents, respectively. Suitable crystal samples were
C
0

G. Pan et al. / Journal of Organometallic Chemistry 580 (1999) 313–319
319
[2] D.A. Smith, B. Zhuang, W.E. Newton, J.W. McDonald, F.A
Schultz, Inorg. Chem. 26 (1987) 2524.
[3] B. Zhuang, L. Huang, L. He, Y. Yang, J. Lu, Acta Chim. Sin.
47 (1987) 25.
mounted on glass fibres on a Siemens SMART [12] area
detector and using graphite-monochromated Mo–Ka
X-radiation (u=0.071073 A). Details of the crystal
˚
parameters, data collection and refinement are given in
Table 3. Data were corrected for Lorentz and polarisa-
tion effects and for absorption effects by SADABS [13].
The structures were solved by conventional direct meth-
ods (SHELXTL) and were refined by the full-matrix
least-squares method on all F2 data using Silicon
Graphics Indy computer [14]. All non-hydrogen atoms
were refined anisotropically; hydrogen atoms were lo-
cated at idealized positions and refined with fixed
isotropic thermal parameters. Atomic coordinates are
given in Tables 4 and 5.
[4] B. Zhuang, G. Pan, L. Huang, Polyhedron 15 (1996) 3019.
[5] M. Minell, J.H. Enemark, R.T.C. Brownlee, M.J. O’Connor,
A.G. Wedd, Coord. Chem. Rev. 68 (1985) 170.
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(1987) 1271.
[7] B. Wang, Y. Sasaki, A. Nagasawa, T. Ito, J. Coord. Chem. 18
(1988) 45.
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Nixon, J. Organomet. Chem. 542 (1997) 265. (b) J.I. Dulebohn,
T.C. Stamatakos, D.L. Ward, D.G. Nocera, Polyhedron 10
(1991) 2813.
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(1997) 918. (b) V. Riera, M.A. Ruiz, F. Villafan˜e, Organometal-
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Acknowledgements
[11] (a) D. Coucouvanis, A. Toupadakis, J.D. Lane, S.M. Koo, C.G.
Kim, A. Hadjikyriacou, J. Am. Chem. Soc. 113 (1991) 5271. (b)
S. Poder-Guillou, P. Schollhammer, F.Y. Pe´tillon, J. Talarmin,
K.W. Muir, P. Baguley, Inorg. Chim. Acta 257 (1997) 153.
[12] SMART Software Reference Manual, Siemens Energy and Au-
tomation Inc., Madison, WI, 1994.
We are grateful to NNSFC and SKLSC for financial
support of this research work.
References
[13] G.M. Sheldrick, SADABS, Absorption Correction Program,
University of Goeltingen, German, 1996.
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[14] G.M. Sheldrick, SHELXTL 5.03, Siemens Analytical X-ray In-
strument Inc., Madison, WI, 1990.
.