Novel higher nuclearity osmium-antimony clusters by alkene- or diene-assisted cluster condensation

Article abstract of DOI:10.1039/b108792d

The reaction of the cluster Os₃(μ-SbPh₂)(μ-H)(μ₃,η ²-C₆H₄)(CO)₉, 1, with a number of alkenes and dienes led to cluster condensation to afford the novel cluster Os₅(μ4-Sb)(μ-SbPh₂)(μ-H)₂(μ ₃,η²-C₆H₄)(μ,η ²-C₆H₄)(CO)₁₄, 3, as the major product, and another novel cluster Os₅(μ₄-Sb)(μ-SbPh₂)(μ-H)(μ ₃,η⁶-C₆H₄)(CO)₁₄ (Ph), 4. Reaction of 3 with the Group 15 ligands EPh₃ (E = P, As, Sb) afforded the corresponding monosubstituted derivatives Os₅(μ₄-Sb)(μ-SbPh₂)(μ-H) ₂(μ₃,η²-C₆H₄) (μ,η²-C₆H₄)(CO)₁₃(EPh ₃), 6.

Full text of DOI:10.1039/b108792d

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Novel higher nuclearity osmium–antimony clusters by alkene- or
diene-assisted cluster condensation
Mingli Deng and Weng Kee Leong*
Department of Chemistry, National University of Singapore, Kent Ridge, 119260, Singapore
Received 27th September 2001, Accepted 3rd January 2002
First published as an Advance Article on the web 21st February 2002
2
The reaction of the cluster Os (µ-SbPh )(µ-H)(µ ,η -C H )(CO) , 1, with a number of alkenes and dienes led to
3
2
3
6
4
9
2
2
cluster condensation to afford the novel cluster Os (µ -Sb)(µ-SbPh )(µ-H) (µ ,η -C H )(µ,η -C H )(CO) , 3, as
5
4
2
2
3
6
6
4
6
4
14
the major product, and another novel cluster Os (µ -Sb)(µ-SbPh )(µ-H)(µ ,η -C H )(CO) (Ph), 4. Reaction of
5
4
2
3
6
4
14
3
with the Group 15 ligands EPh (E = P, As, Sb) afforded the corresponding monosubstituted derivatives
3
2 2
Os (µ -Sb)(µ-SbPh )(µ-H) (µ ,η -C H )(µ,η -C H )(CO) (EPh ), 6.
5
4
2
2
3
6
4
6
4
13
3
Introduction
Reliable and selective synthetic routes to high nuclearity
clusters are still important goals in transition metal carbonyl
cluster chemistry. Among those routes that have emerged are
photochemical activation, reaction of activated clusters with
1
neutral mono- or di-metal complexes, condensation reactions,
“
2
3
capping” reactions, and surface-mediated reactions. We have
for some time now been interested in the reactivity of osmium–
antimony clusters, and have recently shown that thermolysis of
Os (CO) (SbPh ) led to condensation affording a large number
3
11
3
4
of high nuclearity clusters containing six osmium atoms.
We report here that the reaction of Os (µ-SbPh )(µ-H)(µ , η -
2
3
2
3
C H )(CO) , 1, with an alkene or a diene gives rise to two novel
6
4
9
Os Sb clusters via a condensation reaction.
5
2
Results and discussion
Thermolysis of the cluster Os (µ-SbPh )(µ-H)(µ ,η -C H )-
2
3
2
3
6
4
(
CO) , 1, by itself gave rise to clusters containing six osmium
9
atoms, which were derived from the condensation of two tri-
4
osmium units. In the course of our investigations into the
reactivity of 1 with organic ligands, we have found that its reac-
Scheme 1
tion with a number of alkenes or dienes invariably gave the
2
2
novelclusterOs (µ -Sb)(µ-SbPh )(µ-H) (µ ,η -C H )(µ,η -C H )-
We have also investigated the reactivity of cluster 3. Thus, it
reacts with Group 15 donor ligands under ambient conditions
to afford the monosubstituted derivatives Os (µ -Sb)(µ-SbPh )-
5
4
2
2
3
6
4
6
4
(
CO) , 3, as one of the major products, together with smaller
amounts of another novel cluster, Os (µ -Sb)(µ-SbPh )-
µ-H)(µ ,η -C H )(C H )(CO) , 4 (Scheme 1 and Table 1). In
14
5
4
2
5
4
2
6
2
2
(
(µ-H) (µ ,η -C H )(µ,η -C H )(CO) (EPh ), 6 (E = P (a); As
3
6
4
6
5
14
2 3 6 4 6 4 13 3
the case of the monoalkenes, the hexaosmium cluster Os -
(b); Sb (c)), in good yields. The solid-state molecular structure
of one of these (6a) has also been determined by a single-crystal
X-ray crystallographic study (Fig. 3).
6
2
(
µ -Sb)(µ-SbPh )(µ-H)(µ ,η -C H ) (C H )(CO) , 5, was also
4 2 3 6 4 2 6 5 16
isolated. This cluster had earlier been shown to be a condensa-
4
tion product of 1. The two novel clusters 3 and 4 have been
The Os Sb metal cores of 3 and 6 may be regarded as being
5
2
characterised spectroscopically as well as by single-crystal
X-ray crystallography; the ORTEP diagrams showing their
molecular structures, together with selected bond parameters,
are given in Figs. 1 and 2, respectively.
derived from that of 5 by elimination of a mononuclear
osmium fragment. Indeed, the bond parameters associated with
the Os(1)Os(2)Sb(6)Os(3)Sb(7) part of the metal core show
similar trends for the three compounds. In particular, the
5
Table 1 Reaction conditions and products for 1 with alkenes/dienes
a
a
a
a
Ligand
Conditions
Yield of 2 (%)
Yield of 3 (%)
Yield of 4 (%)
Yield of 5 (%)
H C᎐CH2
1.5 bar, 100 ЊC
23
20
21
15
41
48
29
39
5
5
6
4
–
–
28
20
2
CH CH᎐CHCO Et
2.0 equivalents, 100 ЊC
5.1 equivalenst, 85 ЊC
1.1 equivalents, 80 ЊC
3
2
PhCH᎐CHCH᎐CHPh
H C᎐C(CH )CH᎐CH
2
2
3
a
%
yields are calculated with respect to moles of Os for consumed 1.
1
020
J. Chem. Soc., Dalton Trans., 2002, 1020–1023
This journal is © The Royal Society of Chemistry 2002
DOI: 10.1039/b108792d

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Fig. 1 ORTEP diagram (organic hydrogens omitted, 50% probability
thermal ellipsoids) and selected bond parameters for 3. Os(1)–Os(2) =
2
.9360(4) Å; Os(2)–Os(3) = 2.9537(5) Å; Os(4)–Os(5) = 3.0305(5) Å;
Os(2)–Sb(6) = 2.5577(6) Å; Os(3)–Sb(6) = 2.8199(6) Å; Os(4)–Sb(6) =
.6527(6) Å; Os(5)–Sb(6) = 2.6563(6) Å; Os(1)–Sb(7) = 2.6470(6) Å;
Os(3)–Sb(7) = 2.6751(6) Å; Os(1)–C(101) = 2.172(9) Å; Os(1)–C(102) =
.340(8) Å; Os(2)–C(102) = 2.222(8) Å; Os(3)–C(102) = 2.277(8) Å;
Fig. 3 ORTEP diagram (organic hydrogens omitted, 50% probability
thermal ellipsoids) and selected bond parameters for 6a. Os(1)–Os(2) =
.9841(9) Å; Os(2)–Os(3) = 2.9660(9) Å; Os(4)–Os(5) = 3.0107(9) Å;
Os(2)–Sb(6) = 2.5668(12) Å; Os(3)–Sb(6) = 2.7820(12) Å; Os(4)–Sb(6) =
.6518(12) Å; Os(5)–Sb(6) = 2.6456(12) Å; Os(1)–Sb(7) = 2.6429(12) Å;
Os(3)–Sb(7) = 2.6631(12) Å; Os(1)–P(8) = 2.419(4) Å; Os(1)–C(102) =
.164(15) Å; Os(2)–C(101) = 2.214(16) Å; Os(2)–C(102) = 2.397(16) Å;
Os(3)–C(101) = 2.317(16) Å; Os(4)–C(201) = 2.180(13) Å; Os(5)–C(202)
2.135(15) Å; Os(1)–Os(2)–Os(3) = 88.06(2)Њ; Os(2)–Sb(6)–Os(3) =
7.21(3)Њ; Os(4)–Sb(6)–Os(5) 69.27(3)Њ; Os(1)–Sb(7)–Os(3)
02.42(4)Њ.
2
2
2
Os(4)–C(201) = 2.156(9) Å; Os(5)–C(202) = 2.148(9) Å; Os(1)–Os(2)–
Os(3) = 87.734(12)Њ; Os(2)–Sb(6)–Os(3) = 66.425(15)Њ; Os(4)–Sb(6)–
Os(5) = 69.615(16)Њ; Os(1)–Sb(7)–Os(3) = 100.15(2)Њ.
2
2
=
6
1
=
=
The structural similarities between 3 and 5 suggest that 5 may
be a precursor of 3. However, both 3 and 5 failed to react with
or without alkenes/dienes under the same reaction conditions,
thus ruling out any connection between them. It thus appears
that 1 may have reacted with the alkene/diene to form an adduct
initially which then undergoes condensation with another
molecule of 1 to afford 3 via the elimination of a mononuclear
osmium fragment; this mononuclear fragment would have
carried off with it the alkene/diene. Such an activation towards
metal–metal bond cleavage by an alkene/diene is consistent
10
with observations on the photoactivation of Os (CO) , and
3
12
11
has also been proposed in another system. We were not able to
isolate or identify any mononuclear species from the reaction
mixture, but we have found that although the ESMS spectrum
of the reaction mixture did not show the presence of 2 it was
among the chromatographically separated products. It is there-
fore possible that the mononuclear species aggregate during
work-up to form 2.
Fig. 2 ORTEP diagram (organic hydrogens omitted, 50% probability
thermal ellipsoids) and selected bond parameters for 4. Os(2)–Os(5) =
2
.8910(6) Å; Os(3)–Os(4) = 2.9985(6) Å; Os(1)–Sb(6) = 2.7265(8) Å;
Os(2)–Sb(6) = 2.7338(6) Å; Os(3)–Sb(6) = 2.6935(8) Å; Os(4)–Sb(6) =
.6738(8) Å; Os(1)–Sb(7) = 2.7066(8) Å; Os(2)–Sb(7) = 2.6469(8) Å;
Os(1)–C(131) = 2.150(10) Å; Os(3)–C(1) = 2.110(11) Å; Os(4)–C(2) =
2
Thus we have found that alkenes and dienes may assist in
cluster condensation reactions via elimination of an osmium
fragment. In particular, the reaction of 1 with alkenes or dienes
gave rise to the novel Os Sb clusters 3 and 4 rather than the
2
1
6
.110(10) Å; Os(5)–Os(2)–Sb(6) = 88.28(2)Њ; Os(1)–Sb(6)–Os(2) =
02.09(2)Њ; Os(2)–Sb(6)–Os(3) 116.60(3)Њ; Os(3)–Sb(6)–Os(4)
7.93(3)Њ; Os(1)–Sb(7)–Os(2) = 104.96(3)Њ.
=
=
5
2
expected Os Sb clusters as obtained from direct thermolysis.
6
2
Os(3)–Sb(6) bond lengths are invariably the longest of the
Os–Sb bonds in each cluster. Indeed that for 3, at a length of
2
.8199(6) Å, is the longest observed to date. An interesting
6
structural feature in cluster 4 is the presence of a µ ,η -C H
ligand, the second such example in osmium cluster chemistry.
A close examination of the C–C bond lengths in this moiety
shows that the C(1)–C(2) bond (1.454(13) Å) is significantly
longer than the others (range from 1.399(14) to 1.406(13) Å),
which are quite close to those of free benzene. This is similar to
the situation in the µ ,η -C H ligands of 3 and 6a, and may
Experimental
3
6
4
4
General procedures
All reactions and manipulations were performed under a nitro-
gen atmosphere by using standard Schlenk techniques. Solvents
were purified, dried, distilled, and kept under nitrogen prior
to use. NMR spectra were recorded on a Bruker ACF 300
6
2
3
6
4
suggest that there is some loss of aromaticity. The latter two
MHz NMR spectrometer as CDCl solutions unless otherwise
3
2
clusters also possess a µ,η -C H ligand; this has only been
stated. Electrospray mass spectra (ESMS) were obtained as an
aqueous methanol (1 : 1, v/v) solution on a Finnigan MAT
LCQ with a capillary voltage of 14 V and temperature of 353
K. Microanalyses were carried out by the microanalytical
laboratory at the National University of Singapore. Cluster 1
6
4
observed in two dinuclear o-phenylene complexes, viz.,
7
,8
Ir (CO) Cp (C H ) and Fe (CO) (C F ), and one trinuclear
2
2
2
6
4
2
8
6
4
2
9
derivative, Os (CO) (µ-H) (µ,η -C H )(HC᎐NC H ). In con-
trast to the µ ,η -C H ligand, these appear to have retained
3
8
3
6
4
6
5
2
3
6
4
4
their aromaticity; the C–C bond distance ranges are 1.363(17) to
.414(12) Å and 1.36(2) to 1.39(2) Å, for 3 and 6a, respectively.
was prepared by the literature method; all other reagents were
1
from commercial sources and used as supplied.
J. Chem. Soc., Dalton Trans., 2002, 1020–1023
1021

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Table 2 Crystal data for 3, 4 and 6a
Compound
3ؒCH Cl
4ؒCH Cl
6aؒ0.5C H
6 14
2
2
2
2
Empirical formula
Formula weight
Temperature/K
C H Cl O Os Sb
1979.97
293(2)
C H Cl O Os Sb
1979.97
223(2)
C H O Os P Sb
58 42 13 5 2
2172.39
223(2)
3
9
22
2
14
5
2
39 22
2
14
5
2
Crystal system
Space group
Triclinic
P1
Orthorhombic
Pbca
Monoclinic
P2 /c
1
¯
a/Å
b/Å
c/Å
α/Њ
β/Њ
γ/Њ
11.7386(2)
13.5125(3)
16.0955(2)
79.6280(10)
75.1440(10)
74.2680(10)
2358.44(7)
2
18.3478(7)
21.7070(9)
23.1622(9)
90
90
90
9224.9(6)
8
2.851
15.047
7072
15.3508(2)
16.8332(3)
24.7394(1)
90
96.180(1)
90
6355.59(14)
4
2.270
3
Volume/Å
Z
Ϫ3
D /Mg m
2.788
14.714
1768
c
Ϫ1
µ/mm
F(000)
10.873
3964
Reflections collected
Independent reflections
Goodness-of-fit on F
11192
18978 [R(int) = 0.0311]
1.142
72060
12701 [R(int) = 0.0944]
0.889
41516
15878 [R(int) = 0.1256]
1.047
2
Final R indices [I>2σ(I )]
R indices (all data)
Largest diff. peak, hole/e Å
R1 = 0.0387, wR2 = 0.0870
R1 = 0.0500, wR2 = 0.0955
1.392, Ϫ1.829
R1 = 0.0502, wR2 = 0.0810
R1 = 0.1039, wR2 = 0.0912
2.432, Ϫ0.879
R1 = 0.0743, wR2 = 0.1014
R1 = 0.1753, wR2 = 0.1305
1.809, Ϫ1.656
Ϫ3
2
2
Reaction of 1 with alkenes or dienes
gaveorangeOs (µ -Sb)(µ-SbPh )(µ-H) (µ ,η -C H )(µ,η -C H )-
5 4 2 2 3 6 4 6 4
(
CO) (PPh ), 6a (15.2 mg, 65%).
13 3
In a typical reaction, cluster 1 (21.5 mg, 18 µmol) and excess
,4-diphenylbuta-1,3-diene (19.2 mg, 93 µmol) were placed in a
Carius tube with hexane (10 mL) and degassed (three freeze–
pump–thaw cycles). The mixture was then heated for 15 h at
1
Cluster 6a. IR (hexane) ν(CO) 2086m, 2068s, 2022 (sh),
Ϫ1
1
2
001m, 1961w (br) cm ; H NMR δ 7.5–6.4 (m, aromatic),
2
3
1
1
Ϫ13.86 (d, J = 7.4 Hz, OsHOs), Ϫ14.75 (s, OsHOs); P{ H}
NMR δ Ϫ5.33 (s). Calculated for C H O Os Sb P: C, 31.02;
H, 1.66; P, 1.45. Found: C, 30.63; H, 1.46; P, 1.20%.
PH
8
5 ЊC until the color changed to a reddish orange. Removal
5
5
35 13
5
2
of solvent and volatiles in vacuo followed by TLC separation
of the residue (hexane/dichloromethane, 5 : 1, v/v, as eluant)
gave Os (CO) , 2 (2.8 mg, 20%) which was identified by its IR
Similar reactions were carried out with AsPh to yield the
3
3
12
2
2
arsine analogue Os (µ -Sb)(µ-SbPh )(µ-H) (µ ,η -C H )(µ,η -
C H )(CO) (AsPh ), 6b (46%), and with SbPh to yield the
stibine analogue Os (µ -Sb)(µ-SbPh )(µ-H) (µ ,η -C H )(µ,η -
C H )(CO) (SbPh ), 6c (61%).
5
4
2
2
3
6
4
spectroscopic characteristics, unreacted 1 (3.2 mg), Os (µ -Sb)-
5
4
2
2
6
4
13
3
3
(
2
(
µ-SbPh )(µ-H) (µ ,η -C H )(µ,η -C H )(CO) ,
3
(4.1 mg,
2
2
3
6
4
6
4
6
14
2
2
5
4
2
2
3
6
4
4%), Os (µ -Sb)(µ-SbPh )(µ-H)(µ ,η -C H )(C H )(CO) ,
4
5
4
2
3
6
4
6
5
14
2
6
4
13
3
0.8 mg, 5%), and Os (µ -Sb)(µ-SbPh )(µ-H)(µ ,η -C H ) -
6 4 2 3 6 4 2
(
C H )(CO) , 5 (4.5 mg, 23%), in that order.
Similar reactions were carried out with ethene, ethyl croton-
6
5
16
Cluster 6b. IR (hexane) ν(CO): 2086m, 2068 (sh), 2025 (sh),
Ϫ1
1
2
6
005s, 1989w, 1967w, 1963w cm ; H NMR (d -toluene) δ 7.7–
8
ate and isoprene, and these are summarised in Table 1.
.4 (m, aromatic), Ϫ13.76 (s, OsHOs), Ϫ14.80 (s, OsHOs).
Calculated for C H AsO Os Sb : C, 30.39; H, 1.62. Found:
C, 30.80;H, 1.92%.
55
35
13
5
2
Cluster 3. IR (hexane) ν(CO) 2085 (sh), 2073s, 2033s, 2023w,
008m, 1991w, 1970w cm ; H NMR δ 7.6–6.6 (m, aromatic),
Ϫ1
1
2
Ϫ14.26 (s, OsHOs), Ϫ15.01 (s, OsHOs). Calculated for
Cluster 6c. IR (hexane) ν(CO) 2087 (sh), 2070 (sh), 2021vs,
001m, 1963w (br) cm ; H NMR δ 7.5–7.1 (m, aromatic),
C H O Os Sb : C, 24.08; H, 1.06. Found: C, 23.84; H, 0.95%.
Ϫ1
1
38
20 14
5
2
2
The presence of dichloromethane in the crystalline samples
Ϫ14.04 (s, OsHOs), Ϫ14.84 (s, OsHOs). Calculated for
C H O Os Sb ؒC H : C, 31.75; H, 2.12. Found: C, 31.61; H,
1
used for the X-ray diffraction study was confirmed by H NMR
55
35 13
5
3
6
14
spectroscopy.
1
.65%. The presence of hexane in the sample used for elemental
1
analysis was confirmed by H NMR spectroscopy.
Cluster 4. IR (hexane) ν(CO) 2094w, 2086w, 2073m, 2063
(
sh), 2035w, 2021w, 2016m, 2010m, 2002 (sh), 1988w, 1976w
Crystal structure determination of 3, 4 and 6a
Ϫ1 1
cm ; H NMR δ 7.7–6.9 (m, aromatic), Ϫ14.34 (s, OsHOs).
Calculated for C H O Os Sb ؒ¼C H : C, 24.75; H, 1.24.
Found: C, 24.64; H, 0.90%. The presence of hexane in the
crystalline samples used for elemental analysis was confirmed
by H NMR spectroscopy.
The crystals were grown by slow cooling of CH Cl /hexane
2
2
38
20 14
5
2
6
14
solutions and were mounted onto glass fibres. Crystal data and
structure refinement details are given in Table 2. The intensities
were measured on a Siemens SMART diffractometer, equipped
with a CCD detector, using Mo-Kα radiation (λ = 0.71073 Å) at
1
2
23(2) K (293(2) K for 3). The data were corrected for Lorentz
Cluster 5. IR (hexane) ν(CO) 2098w, 2086vs, 2060m, 2042vs,
12
Ϫ1
and polarisation effects with the SMART suite of programs,
2
031s, 2016s, 1991w, 1962m cm , which is identical to the
13
4
and for absorption effects with SADABS. The final unit cell
parameters were obtained by least squares on 5888 (3), 7601 (4)
or 8020 (6a) strong reflections. Structural solution and refine-
literature values.
Reaction of 3 with EPh (E ؍ P, As, Sb)
3
14
ment were carried out with the SHELXTL suite of programs.
In a typical reaction, cluster 3 (21.5 mg, 11 µmol) and PPh3
The structures were solved by direct methods to locate the
heavy atoms, followed by difference maps for the light, non-
hydrogen atoms. All the organic hydrogen atoms were placed in
calculated positions. The positions of the metal hydrides in 3
and 6a were located in low angle difference maps while those for
(
(
6.5 mg, 25 µmol) were stirred together in dichloromethane
10 mL) at room temperature until the IR spectrum of the
solution showed that 3 had been consumed (≈1 d). Removal
of the solvent followed by chromatographic separation on
silica gel using dichloromethane/hexane (3 : 7, v/v) as eluant
15
4 were calculated with XHYDEX; those for 3 were refined
1
022
J. Chem. Soc., Dalton Trans., 2002, 1020–1023

View Article Online
5 C. K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, USA, 1976.
6 (a) O. Bastiansen, L. Fernholt, H. M. Seip, H. Kambara and
K. Kuchitsu, J. Mol. Struct., 1973, 18, 163; (b) K. Tamagawa,
T. Iijima and M. Kimura, J. Mol. Struct., 1976, 30, 243.
while those for 4 and 6a were allowed to ride on one of the
osmium atoms to which they were attached. All the hydrides
2
were assigned a fixed isotropic thermal parameter of 0.05 Å .
All non-hydrogen atoms were given anisotropic displacement
parameters in the final refinement.
CCDC reference numbers 171668–171670.
See http://www.rsc.org/suppdata/dt/b1/b108792d/ for crystal-
lographic data in CIF or other electronic format.
7
M. D. Rausch, R. G. Gastinger, S. A. Gardner, R. K. Brown and
J. S. Wood, J. Am. Chem. Soc., 1977, 99, 7870.
8 M. J. Bennett, W. A. G. Graham, R. P Stewart and R. M. Tuggle,
Inorg. Chem., 1973, 12, 2944.
R. D. Adams and N. M. Golembeski, J. Organomet. Chem., 1979,
9
1
72, 239.
0 (a) S. Zobl-Ruh and W. von Philipsborn, Helv. Chim. Acta, 1980,
3, 733; (b) M. I. Bruce, M. Cooke, M. Green and D. J. Westlake,
1
Acknowledgements
6
J. Chem. Soc. A, 1969, 987; (c) M. R. Burke, J. Takats, F.-W. Grevels
and J. G. A. Reuvers, J. Am. Chem. Soc., 1983, 105, 4092; (d ) A. J.
Deeming, S. S. Ullah, A. J. P. Domingos, B. F. G. Johnson and
J. Lewis, J. Chem. Soc., Dalton Trans., 1974, 2093; (e) P. C. Ford,
J. Organomet. Chem., 1990, 383, 339; ( f ) M. J. Bakker, F. W. Vergeer,
F. Hartl, O. S. Jina, X.-Z. Sun and M. W. George, Inorg. Chim. Acta,
This work was supported by the National University of
Singapore (Research Grant No. RP 982751) and one of us
(
M.D.) thanks the University for a Research Scholarship.
2
000, 300–302, 597.
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