Oxidative addition across sb-h and sb-sb bonds by an osmium carbonyl cluster: Trapping the intermediate

Article abstract of DOI:10.1021/om401206d

The cluster Os₃(CO)₁₁(NCCH₃) oxidatively adds across the Sb-H bond in SbPh₂H to afford the clusters Os ₃(CO)₁₁(H)(μ-SbPh₂) and Os ₃(CO)₁₁(μ-H)(μ-SbPh₂)Os ₃(CO)₁₁. Similarly, its reaction with Sb ₂Ph₄ afforded Os₃(CO)₁₁(μ- SbPh₂)₂Os₃(CO)₁₁ as the major product. In both cases, the intermediate from the oxidative addition reaction was trapped as a W(CO)₅ adduct.

Full text of DOI:10.1021/om401206d

Article
pubs.acs.org/Organometallics
Oxidative Addition across Sb−H and Sb−Sb Bonds by an Osmium
Carbonyl Cluster: Trapping the Intermediate
Ying-Zhou Li, Rakesh Ganguly, and Weng Kee Leong*
Division of Chemistry & Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
S
* Supporting Information
ABSTRACT: The cluster Os3(CO)11(NCCH3) oxidatively
adds across the Sb−H bond in SbPh2H to afford the clusters
Os3(CO)11(H)(μ-SbPh2) and Os3(CO)11(μ-H)(μ-SbPh2)-
Os3(CO)11. Similarly, its reaction with Sb2Ph4 afforded
Os3(CO)11(μ-SbPh2)2Os3(CO)11 as the major product. In
both cases, the intermediate from the oxidative addition
reaction was trapped as a W(CO)5 adduct.
AsMe2),8 respectively, in high yields under ambient conditions.
It is thus reasonable to expect that 1 may react similarly with
INTRODUCTION
■
Organometallic clusters containing both main-group and
SbPh2H. Similarly, the distibine Sb2Ph4 may also be expected to
transition metals are of interest because of their distinctive
serve as a potential source for the “SbPh2” moiety through
structural and reactivity patterns which are quite unlike those of
their homometallic main-group-metal or transition-metal
cluster analogues. Over the last 18 years, we have focused on
the preparation and reactivity studies of osmium−antimony
clusters. The choice of osmium rests on its strong metal−metal
cleavage of the weak Sb−Sb bond.9 Examples of the latter
acting as ligands, with the Sb−Sb bond remaining intact, has
also been reported, however.10 We wish to report here our
work on the oxidative addition of 1 with these two substrates as
a synthetic route to new osmium−antimony carbonyl clusters
bond, making it one of the most prolific cluster-forming
and the trapping of the intermediates of the reactions.
elements. For example, osmium forms the most number of
neutral binary carbonyls, which now include Os(CO)5,
RESULTS AND DISCUSSION
Os2(CO)9, Os3(CO)12, Os4(CO)x (x = 14−16), Os5(CO)y (y
= 16, 18, 19), Os6(CO)z (z = 18, 21), Os7(CO)21, Os8(CO)23,
and Os10(CO)26.1 Osmium−antimony clusters have been found
to exhibit distinctive reactivities, which are quite different from
those of its lighter congeners. For example, Os3(CO)10(μ-
H)(μ-SbPh2), first prepared from a salt elimination reaction
between [HOs3(CO)11]− and SbPh2Cl,2 readily undergoes
nucleophilic addition reactions via Os−Os bond cleavage3 and
Sb−C bond cleavage and ortho metalation on thermolysis.4
The thermolyses of Os3 (CO)1 1 (SbPh3 )5 and
Os3(CO)11(SbMe2Ar)6 also followed pathways very different
from those of their phosphine and arsine analogues.
■
The literature method for the preparation of the secondary
stibine SbPh2H was by the reduction of SbPh2Cl with LiAlH4 at
−78 °C followed by a vacuum distillation, to afford it as a
colorless, air-sensitive oil.11 To simplify the procedure, we have
reoptimized the reaction conditions so that it could be carried
out at room temperature and the product obtained by
extraction with dry hexane and kept as such, thus avoiding
distillation and hence decomposition. The H NMR spectrum
of this solution indicated that it was pure enough for
subsequent use, and the concentration was estimated by H
1
1
NMR integration, using pyrazine as internal standard (Figure
S1 (Supporting Information)). The distibine Sb2Ph4 has been
reported to be obtainable, usually as a side product, from the
reaction of the stibide Ph2Sb− with 1,2-dibromoethane or 1,2-
dichloroethane; the stibide Ph2Sb− is obtainable by sodium
reduction of SbPh3 in liquid ammonia.12 A rational synthesis is
via the metathesis of SbPh2H and PhLi in dioxane.11 Given the
convenient synthesis of SbPh2H described above, we decided
on its deprotonotion with n-BuLi to produce the stibide
Ph2Sb−,13 followed by its reaction with SbPh2Cl (Scheme 1).
This has proven to be more convenient in workup and higher
in yield than the reported methods. Owing to the air-sensitive
In contrast to the large number of known cluster compounds
of osmium containing the lighter congeners of group 15, viz., N,
P, and As, those containing the heavier congeners Sb and Bi are
scarce, and even less is known of their reactivity. This is due
largely to the relatively difficult syntheses of the ligands (for
Sb(III), only the trihalides SbX3 (X = Cl, Br, I) and SbPh3, are
available commercially), the usually low yields of reactions, and
the lack of predictability for thermolytic reactions. The
exploration of new, facile syntheses of osmium−antimony
carbonyl clusters, especially the higher nuclearity clusters, under
mild conditions remains a challenge.
An attractive possibility that has come to our attention is
based on reports that the activated osmium cluster
Os3(CO)11(NCCH3) (1) readily reacted with PPh2H or
AsMe2H to give Os3(CO)11(PPh2H)7 or Os3(CO)11(H)(μ-
Received: December 16, 2013
Published: January 28, 2014
© 2014 American Chemical Society
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The ORTEP diagrams for 3 and 6, together with selected
bond parameters, are shown in Figures 2 and 3, respectively.
Scheme 1
1
properties of Sb2Ph4, it was only characterized by its H NMR
spectrum (Figure S2 (Supporting Information)).
The room-temperature reaction of 1 with SbPh2H, in dry
DCM or THF, afforded the clusters Os3(CO)11(H)(μ-SbPh2)
(2) and Os3(CO)11(μ-H)(μ-SbPh2)Os3(CO)11 (3); the
analogous reaction with the distibine Sb2Ph4 afforded
Os3(CO)11(μ-SbPh2)2Os3(CO)11 (6), together with trace
amounts of the known cluster Os3(CO)10(μ-SbPh2)2 (5)
(Scheme 2).
Scheme 2
Figure 2. ORTEP plot showing the molecular structure of 3. Thermal
ellipsoids are drawn at the 50% probability level, with organic
hydrogen atoms omitted for clarity. Selected bond lengths (Å):
Os(1)−Os(2) = 3.0105(6), Os(2)−Os(3) = 2.8939(6), Os(1)−Os(3)
= 2.8609(6), Os(1)−Sb(1) = 2.6744(7), Os(4)−Sb(1) = 2.6391(8),
Os(4)−Os(5) = 2.9143(6), Os(5)−Os(6) = 2.8832(6), Os(4)−Os(6)
= 2.8498(6).
Cluster 2 has previously been prepared by the carbonylation
of Os3(CO)10(μ-H)(μ-SbPh2) (4) and was only characterized
spectroscopically. We have now characterized it by a single-
crystal X-ray crystallographic analysis. Unlike the arsenic
analogue Os3(CO)11H(μ-AsMe2), which was found to be
unstable on silica, losing a CO ligand on exposure to light,8
cluster 2 is relatively more stable but does decarbonylate
quantitatively to 4 under refluxing DCE. An ORTEP plot
showing the molecular structure of 2 is given in Figure 1. It has
Figure 3. ORTEP plot showing the molecular structure of 6. Thermal
ellipsoids are drawn at the 50% probability level, with organic
hydrogen atoms omitted for clarity. Selected bond lengths (Å):
Os(1)−Os(2) = 2.9837(7), Os(1)−Sb(7) = 2.6928(9), Os(2)−Os(3)
= 2.9996(6), Os(3)−Sb(7) = 2.6791(9), Os(3)−Sb(8) = 2.6893(9),
Os(4)−Sb(8) = 2.6577(9), Os(4)−Os(5) = 2.8599(7), Os(5)−Os(6)
= 2.8890(7), Os(4)−Os(6) = 2.8923(7).
Both clusters consist of an Os3(CO)11 unit linked by an SbPh2
moiety to another: an Os3(CO)11(μ-H) unit and an
Os3(CO)10(μ-SbPh2) unit, for 3 and 6, respectively. Both
clusters are electron precise. In 3, as has already been well
documented,14 the hydride-bridged Os−Os bond (Os(1)−
Os(2) = 3.0105(6) Å) is significantly longer than the other two
Os−Os bonds (Os(1)−Os(3) = 2.8609(6) Å and Os(2)−
Os(3) = 2.8939(6) Å). In 6, one of the Os−Os bond is not
present (Os(1)···Os(3) = 4.308 Å), as required by the valence
electron count. In solution, 6 exists as a mixture of two isomers.
This is apparent from its 1H and 13C{1H} NMR spectra, which
showed two sets of resonances in a ca. 1:4 ratio. These probably
correspond to the Os3(CO)11(SbPh2) fragment occupying
either of two different equatorial positions with respect to the
Figure 1. ORTEP plot showing the molecular structure of 2. Thermal
ellipsoids are drawn at the 50% probability level, with organic
hydrogen atoms omitted for clarity. Selected bond lengths (Å):
Os(1)−Sb(4) = 2.6891(5), Os(1)−Os(2) = 2.9977(4), Os(2)−Os(3)
= 2.9542(4), Os(3)−Sb(4) = 2.6309(5).
the same structure as the arsenic analogue; an Os−Os bond has
been cleaved and the Os3Sb metal core adopts a puckered four-
membered-ring structure. The hydride ligand is in a terminal
coordination mode and is consistent with the singlet 1H
resonance at δ −8.39 ppm.
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Sb atom in the Os3(CO)11(μ-SbPh2) fragment: i.e., one isomer
corresponds to that in the solid-state structure, and the other
has the positions of the Os3(CO)11(SbPh2) fragment and
CO(33) interchanged. The presence of such isomers has also
been observed in other structural analogues: viz., the known
clusters Os3(CO)10(H)(μ-SbPh2)(L) (where L = PPh3, AsPh3,
SbPh3).3a As has already been observed in the simpler
Os3(CO)11(L) clusters,15 the SbPh2 moiety leads to length-
ening of the Os−Os bond that is cis to it on the Os3(CO)11
unit; these are the Os(4)−Os(5) and Os(4)−Os(6) bonds of 3
and 6, respectively.
The proposed reaction pathway is common for both
substrates (Scheme 3) and involves initial substitution of the
Scheme 3
1
Figure 4. H NMR spectra of the reaction of 1 with SbPh2H in d2-
DCM, monitored over time: (a) after 10 min at 0 °C and (b) after 205
min at 0 °C; warmed to room temperature and then (c) after 10 min,
(d) after 1 h, (e) after 2.5 h, and (f) after 31 h.
methane) reaching a maximum after ca. 2.5 h. After that, the
amount of 2 increased at the expense of B; the sum of their
intensities remained nearly constant, indicating the conversion
of B to 2, and B completely disappeared after about 30 h. A
new resonance at δ −18.95 ppm, assignable to 3, also became
more obvious after 2.5 h at room temperature, but the intensity
remained nearly constant over time. This assignment for 3 is
also supported by a repeat NMR experiment in which, after 20
h at room temperature, when the resonance at δ −18.50 ppm
was prominent, addition of a further quantity of 1 resulted in
the rapid disappearance of this resonance (ca. 10 min),
accompanied by a slight increase in the resonance at δ −18.95
(Figure S4 (Supporting Information)).
The intermediate B is interesting, as it can be viewed as a
stibine in which one of its substituents is a bulky organometallic
cluster. The above reaction pathway also suggests that B may
be trapped chemically. Indeed, reactions with the stibine or
distibine in the presence of W(CO)5(NCCH3) afforded the
heteronuclear cluster Os3(CO)11(μ-H)(μ-SbPh2)W(CO)5 (7)
or Os3(CO)11(μ-SbPh2)2W(CO)5 (8), respectively, albeit in
low yields. Both clusters have been completely characterized,
including by single-crystal X-ray crystallographic studies;
ORTEP plots showing their molecular structures, together
with selected bond parameters, are given in Figures 5 and 6,
respectively. The overall structures of 7 and 8 are very similar.
Both have the Ph2SbW(CO)5 group cis to the μ-X moiety; this
is consistent with the proposed structure for the intermediate
B. As in the case of its analogue 6, cluster 8 also exists as a
mixture of two isomers in solution, as is evident from its 1H and
13C{1H} NMR spectra.
CH3CN ligand in 1 to form intermediate A; this is typical of its
reactivity pattern with group 15 ligands.6−8,16 Oxidative
addition of the Sb−X bond (where X = H, SbPh2) across an
Os−Os bond generates the intermediate B, which carries a lone
pair on the trivalent Sb; oxidative addition of M−H bonds (M
= Ge, Sn) to clusters have been extensively studied by the
Adams group.17 An alternative to B would be the species
Os3(CO)11(X)(μ-SbPh2) (B′), which would be indistinguish-
able for X = SbPh2 but for X = H is identical with 2. This would
imply that the formation of 3 involved 2 as the intermediate;
that would require a fair amount of rearrangement, and we have
also verified that 2 does not react with 1 to afford 3.
From B, coordination of the Sb atom onto a neighboring Os
via Os−Os bond cleavage would give 2 or 5.3a Alternatively, it
can coordinate to another “Os3(CO)11” fragment (cluster 1 is
the synthetic equivalent for this synthon) to afford 3 or 6. As
one may expect, the former intramolecular rearrangement
should be more favorable. Consistent with this is the
observation that 3 was only obtained as a minor product and
its yield decreased when a larger excess of SbPh2H was used.
For X = SbPh2, on the other hand, the formation of 5 from B
would require an additional isomerization step about the Os
carrying the terminal SbPh2 ligand so that it is trans to the μ-X
moiety and hence cis to an Os−Os bond. This requirement
favors the formation of 6 over 5.
We have also attempted to monitor the reaction of 1 with
1
SbPh2H by H NMR spectroscopy; 2 equiv of the latter was
used in order to suppress the formation of 3 (Figure 4 and
Figure S3 (Supporting Information)). Four resonances were
observed in the hydride region 10 min after mixing the reagents
at 0 °C, at δ −8.72, −9.90, −17.1, and −18.50 ppm. The lowest
field resonance can be assigned to 2 and that highest field
tentatively to the intermediate B; the remaining two smaller
resonances were transients and have not been assigned. The
spectrum remained little changed at this temperature even after
ca. 205 min at 0 °C, indicating a slow reaction rate. When the
system was warmed to room temperature, the intensities of the
resonances for 2 and B increased over time, the sum of their
intensities (with respect to the residue peak of d2-dichloro-
CONCLUDING REMARKS
■
In this work, we have described a facile approach to osmium−
antimony carbonyl clusters through the reaction of the lightly
stabilized cluster Os3(CO)11(NCCH3), with a secondary
stibine or a distibine. These reactions proceed via oxidative
addition across the Sb−H or Sb−Sb bond, and we have shown
that the proposed intermediate contains a trivalent Sb moiety,
which can be observed by NMR and also trapped chemically.
We believe that this intermediate can be viewed as a bulky
tertiary stibine, with an organometallic cluster serving as a
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Preparation of SbPh2H. To a suspension of LiAlH4 (60 mg, 1.6
mmol) in ether (40 mL) was added a solution of SbPh2Cl (720 mg,
2.3 mmol) in ether (20 mL). Excessive stirring was avoided, as it
would hinder the sedimentation of LiAlH4 in the process of
purification. After 1 h of gentle stirring at room temperature, the
solvent volume was reduced to ca. 1 mL under vacuum and then
extracted with dry hexane (20 mL). The precipitate was allowed to
settle to the bottom and the supernatant carefully transferred with a
pipet into a Carius tube. The crude product solution was stored at 4
°C for subsequent use. 1H NMR (C6D6): δ 7.45−7.55 (dd, 4H, 3JH,H
2.1 Hz, PhH), 7.25−7.35 (m, 6H, PhH), 5.70 (s, 1H, SbH).
=
Preparation of Sb2Ph4. The Ph2SbH solution in hexane (20 mL,
ca. 0.10 M, 2.0 mmol), prepared as described above, was transferred to
a 150 mL Carius tube followed by the addition of THF (30 mL). Then
n-BuLi solution in hexane (1.6 M, 1.2 mL, 1.9 mmol) was added
dropwise to the above solution maintained at −78 °C. The color
immediately changed from colorless to dark red. Ph2SbCl (0.62 g, 2.0
mmol) was then slowly added, after which the reaction mixture was
warmed to room temperature. The color of the solution changed
gradually to yellow over a period of 20 min. The solvent was removed
in vacuo and the residue extracted with dry ether (20 mL). The ether
solution was kept at −30 °C overnight, from which yellow Sb2Ph4
crystallized out. Yield: 0.70 g, 63%. 1H NMR (C6D6) δ 7.53−7.56 (dd,
Figure 5. ORTEP plot showing the molecular structure of 7. Thermal
ellipsoids are drawn at the 50% probability level, with organic
hydrogen atoms omitted for clarity. Selected bond lengths (Å):
Os(1)−Os(2) = 3.0290(2), Os(1)−Os(3) = 2.8785(2), Os(2)−Os(3)
= 2.8936(3), Os(1)−Sb(1) = 2.6953(3), Sb(1)−W(1) = 2.8017(3).
3
8H, JH,H = 1.8 Hz, PhH), 6.99−7.04 (m, 12H, PhH).
Reaction of 1 with SbPh2H. Cluster 1 (50 mg, 54 μmol) was
dissolved in dry DCM (10 mL). To this was added the crude Ph2SbH/
hexane solution (50 μL, ca. 50 μmol). The resulting yellow mixture
was stirred at room temperature for 4 h. The solvent was removed
under reduced pressure and the residue separated by silica TLC.
Elution with DCM/hexane (1/1 v/v) afforded two main bands.
The first, light yellow, band was identified as Os3(CO)11(H)(μ-
SbPh2) (2) (Rf = 0.75; yield 36 mg, 61%). IR (CH2Cl2): ν(CO) 2117
1
m, 2077 s, 2046 s, 2034 vs, 2015 m, 1991 m, 1970 w cm−1. H NMR
(C6D6): δ 7.7 (d, 2H), 7.4−7.5 (d, 2H), 6.9−7.0 (m, 6H), −8.39 (s,
1H, OsH). 13C{1H} NMR (CDCl3): δ 176.74 (br, CO), 174.63 (CO),
169.41 (CO), 136.49 (Ph), 133.37 (Ph), 130.30 (Ph), 129.43 (Ph),
129.13 (Ph), 128.56 (Ph), 127.74 (Ph), 120.88 (Ph). Anal. Calcd for
C23H11O11Os3Sb·0.3THF: C, 24.7; H, 1.2. Found: C, 24.7; H, 0.9.
HRMS (ESI+): calcd for [M + H]+ (C23H12O11Os3Sb+) 1155.835,
found 1155.830.
The second, dark yellow, band afforded a small amount of the dark
yellow product Os3(CO)11(μ-H)(μ-SbPh2)Os3(CO)11 (3) (Rf = 0.60;
yield 11 mg, 24%). IR (CH2Cl2): ν(CO) 2142 w, 2103 w, 2093 s, 2060
Figure 6. ORTEP plot showing the molecular structure of 8. Thermal
ellipsoids are drawn at the 50% probability level, with organic
hydrogen atoms omitted for clarity. Selected bond lengths (Å):
Os(1)−Os(3) = 2.9940(3), Os(1)−Sb(5) = 2.6797(5), Os(1)−Sb(6)
= 2.6870(4), Os(2)−Os(3) = 2.9611(4), Os(2)−Sb(5) = 2.6850(5),
W(4)−Sb(6) = 2.7984(4).
1
s, 2051 m, 2016 vs cm−1. H NMR (C6D6) δ 7.65 (d, 6H), 7.02 (t,
4H), −18.89 (s, 1H, OsHOs). 13C{1H} NMR (CD2Cl2): δ 185.26
(4C, CO), 181.06 (4C, CO), 173.09 (2C, CO), 173.07 (2C, CO),
172.28 (1C, CO), 172.25 (1C, CO), 168.89 (2C, CO), 168.33 (2C,
CO), 162.69 (1C, CO), 162.67 (1C, CO), 162.40 (1C, CO), 162.33
(1C, CO), 134.80 (Ph), 132.31 (Ph), 129.47 (Ph), 128.66 (Ph). Anal.
Calcd for C34H11O22Os6Sb: C, 20.1; H, 0.6. Found: C, 20.1; H, 0.6.
HRMS (ESI+): calcd for [M + H]+ (C34H12O22Os6Sb+) 2035.647,
found 2035.647.
Thermolysis of 2. A solution of 2 (30 mg, 26 μmol) in 1,2-
dichloroethane (10 mL) was refluxed for 12 h. After the solvent was
removed under reduced pressure, TLC separation with DCM/hexane
(1/4, v/v) as the eluent yielded an orange band of Os3(CO)10(μ-
H)(μ-SbPh2) (4) (Rf = 0.40; yield 25 mg, 85%), which was identified
by a comparison of its IR and 1H NMR data with the literature values.2
Reaction of 1 with Sb2Ph4. To a solution of 1 (30 mg, 33 μmol)
in dry DCM (10 mL) was added Sb2Ph4 (18 mg, 33 μmol). The
resulting yellow mixture was stirred at room temperature for 48 h.
TLC separation of the residue after solvent removal, with DCM/
hexane (1/1 v/v) as the eluent, gave two yellow bands.
substituent, and may be employed as such; work on this is
currently underway.
EXPERIMENTAL SECTION
■
General Data. All manipulations were carried out under an argon
atmosphere with standard Schlenk techniques. Reagent grade solvents
were dried by the standard procedures and were freshly distilled prior
to use. Os3(CO)11(NCCH3) (1),18 SbPh2Cl,19 and W-
(CO)5(NCCH3)20 were prepared as described in the literature. The
TLC plates used were from a commercial source (silica gel 60 F254,
1
Merck Co.). H NMR spectra were recorded on Bruker AV 300 and
BBF O1 400 spectrometers and the chemical shifts referenced to
residual solvent peaks in the respective deuterated solvents. Infrared
spectra were acquired as CH2Cl2 solutions on a Bruker ALPHA FTIR
spectrometer. High-resolution mass spectra were recorded in ESI
mode on a Waters UPLC-Q-TOF mass spectrometer. Elemental
analyses were performed by the microanalytical laboratories at the
Nanyang Technological University or the National University of
Singapore.
The first band, obtained in trace amounts, was identified as the
known cluster Os3(CO)10(μ-SbPh2)2 (5) by comparing its IR spectral
values with those in the literature.2b
The second band, the major product, was identified as
Os3(CO)11(μ-SbPh2)2Os3(CO)11 (6) (Rf = 0.50; yield 20 mg, 53%).
IR (CH2Cl2): ν(CO) 2123 s, 2101 s, 2083 s, 2050 vs, 2039 s, 2014 s,
1
1981 w, 1942 w cm−1. H NMR (C6D6, major isomer): δ 6.81−6.96
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(m, 12H), 6.98−7.04 (dd, 4H), 7.36−7.39 (dd, 4H). 13C{1H} NMR
(CDCl3, major isomer): δ 187.13 (4C, CO), 179.50 (2C, CO), 177.34
(4C, CO), 174.73 (4C, CO), 172.22 (2C, CO), 170.65 (2C, CO),
168.24 (2C, CO), 164.34 (2C, CO), 135.27 (Ph), 135.10 (Ph), 131.52
(Ph), 130.21 (Ph), 129.14 (Ph), 128.96 (Ph), 128.10 (Ph), 123.55
(Ph). Anal. Calcd for C46H20O22Os6Sb2·0.8THF: C, 25.0; H, 1.1.
Found: C, 25.3; H, 0.9. HRMS (ESI+): calcd for [M + H]+
CELL_NOW,24 and the reflection data were processed and
corrections applied using the program TWINABS.25 A dichloro-
methane solvate was found for the crystal of 3, and a thf with partial
occupancy (fixed at 0.8) was found for the crystal of 6. All non-
hydrogen atoms were refined with anisotropic thermal parameters.
Metal hydrides were placed by potential energy calculations using the
XHYDEX program26 and were refined riding on an Os atom to which
they were attached, with fixed isotropic thermal parameters. Crystal
data, data collection parameters, and refinement data are summarized
in Table S1 (Supporting Information).
+
(C46H21O22Os6Sb2 ) 2308.615, found 2308.611.
Reaction of 1, W(CO)5(NCCH3), and SbPh2H. Cluster 1 (60 mg,
65 μmol) and W(CO)5(NCCH3) (24 mg, 65 μmol) were dissolved in
dry DCM (10 mL). To this was added the crude Ph2SbH/hexane
solution (0.65 mL, ca. 65 μmol). The resulting yellow mixture was
stirred at room temperature for 26 h. The solvent was removed under
reduced pressure and the residue separated by silica TLC. Elution with
DCM/hexane (1/2 v/v) afforded several bands.
ASSOCIATED CONTENT
* Supporting Information
■
S
CIF files, a table, and figures giving crystallographic data for all
structures, all NMR, IR, and HR-MS spectra, and elemental
analyses. This material is available free of charge via the Internet
at http://pubs.acs.org.
The first, light yellow, band was identified as 2 (Rf = 0.65; yield 40
mg, 57%).
The second, light yellow, band was identified as unconsumed
W(CO)5(NCCH3), which gradually decomposed in DCM solution.
The third, light yellow, band was identified as Os3(μ-H)(CO)11(μ-
SbPh2)W(CO)5 (7) (Rf = 0.35; yield 5.0 mg, 5.2%). IR (CH2Cl2):
ν(CO) 2140 w, 2092 s, 2063 vs, 2038 w, 2028 w, 2011 m, 1985 w,
1930 vs cm−1. 1H NMR (C6D6): δ 7.70 (d, 4H), 7.10 (t, 4H), 7.02 (t,
2H), −18.89 (s, 1H, OsHOs). 13C{1H} NMR (CD2Cl2): δ 201.14
(1C, CO), 199.16 (4C, CO), 185.82 (2C, CO), 181.52 (2C, CO),
173.27 (2C, CO), 172.90 (1C, CO), 169.44 (1C, CO), 168.66 (1C,
CO), 163.21 (1C, CO), 162.45 (1C, CO), 135.27 (Ph), 131.58 (Ph),
129.07 (Ph), 128.73 (Ph). Anal. Calcd for C28H11O16Os3SbW: C, 22.7;
H, 0.8. Found: C, 23.0; H, 1.0. HRMS (ESI+): calcd for [M + H]+
(C28H12O16Os3SbW+) 1479.746, found 1479.750.
AUTHOR INFORMATION
Corresponding Author
■
*.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by Nanyang Technological University
through a startup grant (Grant no. 4080504). Y.-Z.L. thanks the
university for a Research Scholarship.
The fourth, dark yellow, band was identified as 3 (Rf = 0.30; yield
7.0 mg, 13%).
REFERENCES
■
Reaction of 1, W(CO)5(NCCH3), and Sb2Ph4. To a solution of 1
(60 mg, 65 μmol) and W(CO)5(NCCH3) (24 mg, 65 μmol) in dry
DCM (10 mL) was added Sb2Ph4 (36 mg, 65 μmol). The resulting
yellow mixture was stirred at room temperature for 96 h. After solvent
removal, the residue was separated by TLC. Elution with DCM/
hexane (2/3 v/v) afforded several bands.
The first band, obtained in trace amounts, was identified as 5.
The second, light yellow, band was identified as unconsumed
W(CO)5(NCCH3).
The third, light yellow, band was identified as Os3(CO)11(μ-
SbPh2)2W(CO)5 (8) (Rf = 0.50; yield 5.0 mg, 4.4%). IR (CH2Cl2):
ν(CO) 2122 s, 2082 s, 2061 w, 2048 w, 2038 s, 2022 w, 2003 m, 1976
w, 1927 s cm−1; .1H NMR (C6D6, major isomer): δ 7.54 (d, 4H, PhH),
7.08−7.11 (q, 4H, PhH), 6.82−6.95 (m, 12H, PhH). 13C{1H} NMR
(CD2Cl2, major isomer): δ 201.41 (1C, CO), 198.97 (4C, CO),
188.01 (2C, CO), 180.27 (1C, CO), 177.55 (2C, CO), 174.97 (2C,
CO), 172.31 (1C, CO), 171.27 (1C, CO), 168.50 (1C, CO), 164.50
(1C, CO), 135.57 (Ph), 135.24 (Ph), 131.39 (Ph), 130.10 (Ph),
129.05 (Ph), 128.46 (Ph), 128.16 (Ph), 123.23 (Ph). Anal. Calcd for
C40H20O16Os3Sb2W: C, 27.4; H, 1.2. Found: C, 27.7; H, 1.4. HRMS
(ESI+): calcd for [M + H]+ (C40H21O16Os3Sb2W+) 1754.720, found
1754.720.
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