Chemical transformations on diols anchored to a triosmium cluster

Article abstract of DOI:10.1039/b103800c

Clusters of the general formula Os3(μ-H)(CO)10(μ-O-OH), 2, have been synthesised from the reaction of Os3-(μ-H)(CO)10(μ-OH) with the appropriate glycol. The free-OH function of the glycol derivative, OS3(μ-H)(CO)10-(μ-OCH2CH2OH), 2a, can be elaborated by esterification with benzoyl chloride to give Os3(μ-H)(CO)10-(μ-OCH2CH2OC(O)Ph), 3, and partially oxidised to give Os3(μ-H)(CO)10(μ-OCH2CHO), 4a. Cluster 4a itself can undergo allylation to give Os3(μ-H)(CO)10(μ-OCH2CH(OH)CH2Ch=CH2), 5, or react with PhMgBr to give Os3(μ-H)(CO)10(μ-OCH2CH(OH)Ph), 2e. Cluster 2a can also be functionalised at the cluster metal core with PPh3 as Os3(μ-H)(CO)9(μ-OCH2CH2OH)(PPh3), 6.

Full text of DOI:10.1039/b103800c

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Chemical transformations on diols anchored to a triosmium cluster
Mien Wei Lum and Weng Kee Leong*
Department of Chemistry, National University of Singapore, Kent Ridge, Singapore 119260
Received 26th April 2001, Accepted 26th June 2001
First published as an Advance Article on the web 13th August 2001
Clusters of the general formula Os3(µ-H)(CO)10(µ-O–OH), 2, have been synthesised from the reaction of Os3-
(µ-H)(CO)10(µ-OH) with the appropriate glycol. The free –OH function of the glycol derivative, Os3(µ-H)(CO)10-
(µ-OCH2CH2OH), 2a, can be elaborated by esterification with benzoyl chloride to give Os3(µ-H)(CO)10-
(µ-OCH2CH2OC(O)Ph), 3, and partially oxidised to give Os3(µ-H)(CO)10(µ-OCH2CHO), 4a. Cluster 4a
itself can undergo allylation to give Os (µ-H)(CO) (µ-OCH CH(OH)CH CH᎐CH ), 5, or react with PhMgBr
᎐
3
10
2
2
2
to give Os3(µ-H)(CO)10(µ-OCH2CH(OH)Ph), 2e. Cluster 2a can also be functionalised at the cluster metal core
with PPh3 as Os3(µ-H)(CO)9(µ-OCH2CH2OH)(PPh3), 6.
Introduction
Results and discussion
Organometallic clusters offer the possibility of unique trans-
formations as a result of synergistic interactions among the
metal atoms. One of our long-term goals is to study the inter-
action between two ligands bound onto a cluster surface. In
order to do so, it is useful to begin with a fairly robust cluster
that is not likely to degrade or change in nuclearity in the course
of the study and in that respect, the triosmium framework
appears to be very well suited for the purpose. A second
important requirement is the ability to anchor various organic
molecules onto the cluster in a specific manner. This is not
a trivial task since the reaction of clusters with even simple
organic molecules can be notoriously complicated. For
instance, the type of products obtained from the reaction of
Os3(CO)10(NCCH3)2 with amines depend on the amines used.1
For a sufficiently large molecule, the different functionalities
lead to increased complexity and usually the most reactive
functionality will dictate the major reaction product obtained,
which may not be the desired one. For instance, the reaction of
Os3(CO)10(NCCH3)2 with 2-furaldehyde gave a product in
which the furaldehyde had undergone C–H cleavage at the
aldehyde functionality, bonding to the cluster via the resultant
acyl group; the acyl group could thermally decarbonylate to
give a product in which the furan ring (without the aldehyde
group) was now bound to the cluster. Hence it was not possible
to obtain, say, a product in which the 2-furaldehyde was bound
to the cluster via the furan ring with the aldehyde group still
intact.2
One strategy to afford clusters in which an organic fragment
is anchored in a specific manner is to begin with a cluster that
already contains the anchored linkage and then elaborating on
the remainder of the organic moiety through a series of trans-
formations like those employed in a typical organic synthesis. A
good example of this is the work of Rosenberg et al. on the
employment of carbon-based nucleophiles to attack the carbo-
cyclic ring of triosmium cluster-bound quinolines.3 In order for
this to work, however, the cluster core and the cluster-substrate
linkage must be able to survive the conditions employed in the
organic transformations; the challenge is therefore to seek out a
set of organic transformations and reagents that will allow this.
We would like to report here our initial investigations towards
this challenge, employing as our starting point a triosmium
cluster containing the alkoxy bridge as the substrate-cluster
linkage.
The high-yield synthesis of triosmium clusters containing
bridging alkoxy groups has been reported recently, starting
from either Os3(CO)12 anchored onto silica or the hydroxy-
bridged cluster Os3(µ-H)(CO)10(µ-OH), 1 (Scheme 1).4 We have
Scheme 1
used this methodology to prepare clusters of the type Os3-
(µ-H)(CO)10(µ-O–OH), 2, in which one of the hydroxyl functions
has been anchored onto the trisomium cluster as an alkoxy
group while the other is still free.
The yields of the various cluster-bound diols are given in
Table 1, and it is quite apparent that an increase in the steric
bulk of the substituents about the hydroxyl groups leads to a
decrease in overall yield. Furthermore, it also leads to a prefer-
ence for attachment of the cluster at the primary alcohol group,
for example, 1,2-propanediol gave 2b, in which the 1-hydroxyl
group is anchored, in 38% yield as opposed to 16% for 2c,
which has the 2-hydroxyl group anchored; likewise, 1-phenyl-
1,2-ethanediol gave exclusively 2e (in low yield), with the
primary alcohol function anchored. These observations are in
accord with increasing steric hindrance to attack by the cluster.
The molecular structures of compounds 2a–c and 2e have
been confirmed by single crystal X-ray crystallographic studies;
that for 2a has already been reported.5 The ORTEP plots for 2b,
2c and 2e are shown below (Figs. 1, 2 and 3, respectively), and
selected bond parameters for 2a–c and 2e are collected in Table
2. Both 2a and 2c crystallised in the triclinic system with two
crystallographically distinct molecules in the asymmetric unit;
the Os–Os bond lengths of the alkoxy-bridged edges in the two
chemically equivalent molecules differ by as much as 20σ and
29σ (σ = estimated standard deviation) in 2a and 2c, respect-
ively. This points to the large deviations in structural param-
eters that can occur under the influence of crystal packing
forces. In all four clusters, there is a shortening of the dibridged
Os(µ-H)(µ-O)Os bond lengths (range of 2.7891(5) to 2.8040(7)
Å) relative to the non-bridged Os–Os bonds (range of 2.8098(7)
to 2.8333(6) Å). This net shortening of the dibridged Os(µ-H)-
(µ-X)Os bond is characteristic for systems containing relatively
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This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b103800c

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Table 1 Yields of clusters 2
Diol
Products
Yield (%)
1,2-Ethanediol
1,2-Propanediol
Os3(µ-H)(CO)10(µ-OCH2CH2OH), 2a
Os3(µ-H)(CO)10(µ-OCH2CH(OH)CH3), 2b
Os3(µ-H)(CO)10(µ-OCH(CH3)CH2OH), 2c
Os3(µ-H)(CO)10(µ-OCH2CH2CH2OH), 2d
Os3(µ-H)(CO)10(µ-OCH2CH(OH)Ph), 2e
60
38
16
15
8
1,3-Propanediol
1-Phenyl-1,2-ethanediol
Fig. 1 ORTEP21 diagram of 2b (50% thermal ellipsoids).
Fig. 4 ORTEP diagram of 3 (50% thermal ellipsoids). Selected bond
lengths (Å) and angles (Њ): Os(1)–Os(2) = 2.8016(5), Os(1)–
Os(3) = 2.8237(5), Os(2)–Os(3) = 2.8286(6), Os(1)–O(1) = 2.117(6),
Os(2)–O(1) = 2.102(7), O(1)–C(1) = 1.429(12), C(1)–C(2) = 1.528(16),
O(2)–C(2) = 1.434(14), O(2)–C(3) = 1.336(14), O(3)–C(3) = 1.186(15);
Os(2)–Os(1)–Os(3) = 60.373(14),
Os(1)–Os(2)–Os(3) = 60.200(13),
Os(1)–Os(3)–Os(2) = 59.428(13), Os(1)–O(1)–Os(2) = 83.2(2).
not significantly different, suggesting that the triosmium core
has little structural effect on the organic fragments.
One of the simplest and most common reactions that can be
carried out on an alcohol group is ester formation. Thus we
started with the esterification of 2a with benzoyl chloride. This
gave a compound which showed a similar profile for the CO
absorption bands to 2a, as well as a metal hydride signal in the
1H NMR spectrum at Ϫ12.40 ppm, indicating that the metal
core in 2a was unaffected. An ester linkage was indicated by a
weak 1733 cmϪ1 absorption band, and the 1H resonances in the
organic region were assignable to the presence of a PhC(᎐O)-
᎐
Fig. 2 ORTEP diagram of 2c (50% thermal ellipsoids).
OCH2CH2 moiety. The product was thus identified as the new
cluster Os3(µ-H)(CO)10(µ-OCH2CH2OC(O)Ph), 3. A single
crystal X-ray crystallographic study was also carried out on 3;
an ORTEP plot together with selected bond parameters is given
in Fig. 4. As may be expected from the above discussion, the
bond parameters associated with the cluster core are similar to
those in compounds 2, and those associated with the organic
moiety are within typical ranges.7
A key functional group in organic chemistry is the carbonyl
group, as it is the starting point of a number of C–C bond
formation reactions which may be used to build up molecules.
Our main target was thus the transformation of the free alcohol
group into the corresponding aldehyde. This was a particularly
difficult transformation; we tried several oxidants that either
gave low yields (PCC (pyridinium chlorochromate)8 and
Swern9) or failed completely (PDC (pyridinium dichromate),10
MnO2, KMnO4 and Ag2CO3 11). Eventually, we succeeded with
the Dess–Martin reagent (triacetoxyperiodinane),12 which gave
the clusters Os3(µ-H)(CO)10(µ-OCH2CHO), 4a, and Os3(µ-H)-
(CO)10(µ-OCH2CH2CHO) 4d, from 2a and 2d, respectively,
Fig. 3 ORTEP diagram of 2e (50% thermal ellipsoids).
1
in moderate yields. These clusters exhibited a distinctive H
small X atoms.6 The most noteworthy point, however, is prob-
ably that made earlier on 2a, that the C–O single bond lengths
for the free –OH and the alkoxy bridge in all four clusters are
resonance in the ca. 9 ppm region for the aldehyde functionality.
From 4a, we have carried out two representative C–C bond
formation reactions, viz., allylation and a Grignard reaction.
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Table 2 Selected bond lengths (Å) and angles (Њ) for 2a–c and 2e
Bond parameter
2aa,b
2b
2.8029(5)
2cb
2.7978(6)
2e
2.7891(5)
2.7897(7)
2.8040(7)
Os(1)–Os(2)
2.7850(5)
2.8195(7)
2.8282(7)
2.8198(6)
2.8319(6)
Os(1)–Os(3)
2.8327(6)
2.8318(6)
2.133(6)
2.8206(4)
2.8265(4)
2.113(5)
2.8098(7)
2.8104(7)
2.8333(6)
2.8257(6)
Os(2)–Os(3)
2.100(9)
2.108(9)
2.126(7)
2.123(7)
Os(1)–O(1)
2.109(9)
2.112(9)
2.122(7)
2.117(7)
Os(2)–O(1)
2.114(6)
2.124(5)
1.462(17)
1.413(16)
1.454(12)
1.435(11)
O(1)–C(1)
1.436(12)
1.372(19)c
60.327(14)
60.358(14)
59.316(14)
82.6(2)
1.430(9)
1.418(18)
1.41(2)
1.456(17)
1.426(17)
O(2)–C(2)
1.423(11)
60.508(11)
60.297(11)
59.195(11)
82.321(18)
60.120(18)
59.866(18)
60.576(14)
60.401(15)
Os(2)–Os(1)–Os(3)
Os(1)–Os(2)–Os(3)
Os(2)–Os(3)–Os(1)
Os(1)–O(1)–Os(2)
60.466(18)
60.495(18)
60.097(14)
60.622(15)
59.415(18)
59.640(18)
59.327(14)
58.977(14)
83.0(3)
83.3(3)
82.4(2)
82.1(2)
a From ref. 5. b Two molecules in the asymmetric unit. c Disordered.
For the allylation, we carried out an indium metal-mediated
allylation with allyl bromide in an aqueous THF solution.13 The
new cluster Os (µ-H)(CO) (µ-OCH CH(OH)CH CH᎐CH ), 5,
᎐
3
10
2
2
2
was obtained as a yellow oil. This compound exhibited a
carbonyl stretching profile in the infrared that is only slightly
shifted in frequency as compared to 4a, thus indicating the
integrity of the cluster core. The presence of the allyl group
1
was indicated by H resonances at 5.74 and 5.13 ppm in the
NMR spectrum, characteristic of a C᎐C double bond. The
᎐
formulation for 5 was further supported by a FAB mass spec-
trum, which showed the highest mass fragment centred around
m/z 953 (based on 192Os). Reaction of 4a with PhMgBr afforded
2e in 44% yield (73% wrt consumed 4a).
We have also explored the stability of 2e with respect to
cleavage of the triosmium framework from the organic moiety;
we were of the view that 2e may be regarded as a “partially
protected” 1-phenyl-1,2-ethanediol. Cluster 2e was stirred with
concentrated hydrochloric acid at ambient temperature. An IR
spectrum of the orange residue obtained suggested generation
of the cluster Os3(µ-H)(CO)10(µ-Cl), which was also corrobor-
Fig. 5 ORTEP diagram of 6 (50% thermal ellipsoids). Selected bond
lengths (Å) and angles (Њ): Os(1)–Os(2) = 2.8364(4), Os(1)–
Os(3) = 2.8528(4), Os(2)–Os(3) = 2.8682(4), Os(1)–O(1) = 2.150(5),
Os(2)–O(1) = 2.168(5), O(1)–C(1) = 1.468(9), C(1)–C(2) = 1.514(11),
O(2)–C(2) = 1.423(11), Os(2)–Os(1)–Os(3) = 60.550(10), Os(1)–Os(2)–
Os(3) = 60.007(10), Os(1)–Os(3)–Os(2) = 59.443(10), Os(1)–O(1)–
Os(2) = 82.12(16).
ated by a singlet at Ϫ14.36 ppm in the 1H NMR spectrum.14 1
H
resonances assignable to that of free 1-phenyl-1,2-ethanediol
were also observed, indicating cleavage of the ligand from
the cluster. We were likewise able to “deprotect” 2a similarly to
afford Os3(µ-H)(CO)10(µ-Cl) and the free 1,2-ethanediol.
The ability to transform the cluster core without detriment to
the organic moiety was also of interest to us. We have thus also
carried out a simple amine-N-oxide activated ligand substi-
tution with PPh3 on 2a, which afforded the expected derivative
Os3(µ-H)(CO)9(µ-OCH2CH2OH)(PPh3), 6. Cluster 6 has been
fully characterised spectroscopically, including a single crystal
X-ray crystallographic study (Fig. 5). This substitution with a
phosphine ligand has a very significant effect on the cluster
core; the Os–Os and Os–O bonds are all lengthened with
respect to the parent cluster 2a.
Although the crystal structure indicates that the phosphine
1
ligand is in an equatorial position, the H and 31P{1H} NMR
spectra of 6 indicated that there were two isomers in solution.
There are three possible positions for substitution at one of the
alkoxy bridged osmium atoms (Fig. 6); position A corresponds
to that in the crystal structure. In an earlier work on similar
phosphite-substituted alkoxy-bridged triosmium clusters, Lewis
et al. used the magnitude of 2JPH between the phosphite and the
metal hydride to determine that the two isomers present in solu-
2
tion were of structures A and B; the latter showed a large JPH
2
of ≈50–60 Hz.15 In 6, both isomers have small JPH, indicating
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J. Chem. Soc., Dalton Trans., 2001, 2476–2481

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1 (164 mg, 39%) and 2a (252 mg, 60%) as yellow bands. 2a: νCO
/
cmϪ1: 2110w, 2071vs, 2058m, 2022vs, 2000m, 1987m (liter-
ature:16 2111w, 2071vs, 2059s, 2023vs, 1999s, 1989m, 1982m).
3
1H NMR δ 3.72 (t, 2H, µ-OCH2CH2OH, JHH = 4.9 Hz), 3.64
3
(dt, 2H, OCH2CH2OH, JHH = 5.4 Hz, 4.9 Hz), 1.63 (t,
2H, CH2OH), Ϫ12.44 (s, 1H, OsHOs) (literature:16 3.67(t),
3.48(dt), 1.59(t), Ϫ12.51(s)). Analysis (Found): C, 15.81; H,
0.76. Calc. for C12H6O12Os3: C, 15.78; H, 0.66%.
Fig. 6 Possible substitution positions at an alkoxy bridged osmium;
Newman projection along the bridged Os–Os bond.
Preparation of Os3(ꢀ-H)(CO)10(ꢀ-OCH2CH(OH)CH3) 2b
and Os3(ꢀ-H)(CO)10(ꢀ-OCH(CH3)CH2OH), 2c.
A similar
reaction starting from 1 (63.9 mg, 73.6 µmol) and 1,2-
propanediol (2.5 mL) yielded unreacted 1 (25.6 mg, 40%),
Os3(µ-H)(CO)10(µ-OCH2CH(OH)CH3), 2b (25.8 mg, 38%) and
Os3(µ-H)(CO)10(µ-OCH(CH3)CH2OH), 2c (11.1 mg, 16%).
2b: νCO/cmϪ1: 2110w, 2070vs, 2059m, 2023vs, 2016sh, 2007w,
1999s, 1989m. 1H NMR δ 3.83 (m, 1H, CH), 3.69 (dd, 1H, CH2,
3
3
2JHH = 10.2 Hz, JHH = 8.8 Hz), 3.31 (dd, 1H, CH2, JHH = 2.9
3
Hz), 1.97 (d, 1H, OH), 1.06 (d, 3H, CH3, JHH = 5.9 Hz),
Ϫ12.39 (s, 1H, OsHOs). Analysis (Found): C, 16.91; H, 0.97.
Calc. for C13H8O12Os3: C, 16.84; H, 0.86%.
2c: νCO/cmϪ1: 2110w, 2070vs, 2059m, 2023vs, 2016sh, 2007w,
1
1999s, 1989m. H NMR δ 4.75 (m, 1H, CH), 3.76 (dd, 1H,
2
3
CH2, JHH = 10.7 Hz, JHH = 2.6 Hz), 3.47 (dd, 1H, CH2,
3JHH = 9.4 Hz), 2.36 (d, 1H, CH3, 3JHH = 1.8 Hz), 2.00 (br s, 1H,
OH), Ϫ12.35 (s, 1H, OsHOs). Analysis (Found): C, 16.88; H,
1.06. Calc. for C13H8O12Os3: C, 16.84; H, 0.86%.
Preparation of Os3(ꢀ-H)(CO)10(ꢀ-OCH2CH2CH2OH), 2d. A
similar reaction of 1 (73.6 mg, 84.8 µmol) and 1,3-propanediol
(1.5 mL) afforded unreacted 1 (50.6 mg, 69%) and Os3(µ-H)-
Fig. 7 Reagents and conditions: (i) PhCOCl, Et3N, THF, 2 h. (ii)
(CO)10(µ-OCH2CH2CH2OH), 2d (11.6 mg, 15%). νCO/cmϪ1
:
Dess–Martin reagent, CH2Cl2,
6 h, followed by saturated aq.
2110m, 2071vs, 2059m, 2024vs, 1999m, 1987m. 1H NMR δ 3.69
NaHCO3 ϩ Na2S2O3. (iii) CH2᎐᎐CHCH2Br, indium metal, THF–H2O
(1 : 1), 1 d. (iv) PhMgBr, anhydrous THF, Ϫ20 ЊC, 2.5 h, followed by
aq. HCl. (v) Conc. HCl, CH2Cl2. (vi) Me3NOؒ2H2O, followed by PPh3.
3
(t, 2H, OCH2CH2, JHH = 6.6 Hz), 3.66 (q, 2H, CH2CH2OH,
3JHH = 5.9 Hz), 1.72 (q, 2H, CH2CH2), 1.29 (t, 1H, CH2OH),
Ϫ12.46 (s, 1H, OsHOs). MS (FAB): m/z 926 (Calculated for
Mϩ, 927).
that the second isomer probably corresponds to substitution at
position C; this is the less sterically hindered of the two pseudo-
axial positions.
In conclusion, we have shown that it is possible to transform
a glycol that has been anchored onto a triosmium cluster
with judicious choice of the synthetic methods in the organic
synthesis arsenal. The transformations that we have studied,
together with investigations into the chemical stability of the
organic-cluster linkage, and of the metal core, are summarised
below starting from cluster 2a (Fig. 7).
Preparation of Os3(ꢀ-H)(CO)10(ꢀ-OCH2CH(OH)Ph), 2e. A
similar reaction of 1 (75.3 mg, 86.7 µmol) and 1-phenyl-1,2-
ethanediol (104.5 mg, 75.7 mmol) afforded unreacted 1 (67.0
mg, 89%) and Os3(µ-H)(CO)10(µ-OCH2CH(OH)Ph), 2e (7.0
mg, 8%). νCO/cmϪ1: 2110w, 2071vs, 2059s, 2022vs, 2016s, 2007m,
1999s, 1987m. 1H NMR δ 7.31 (m, 5H, Ph), 4.75 (m, 1H,
2
3
CH(OH)), 3.76 (dd, 1H, CH2, JHH = 11.0 Hz, JHH = 9.5 Hz),
3.47 (dd, 1H, CH2, 3JHH = 2.9 Hz), 2.37 (d, 1H, OH, 3JHH = 1.5
Hz), Ϫ12.39 (s, 1H, OsHOs). Analysis (Found): C, 22.01; H,
1.06. Calc. for C18H10O12Os3: C, 21.85; H, 1.01%.
Experimental
General procedures
Esterification reactions of 2a with benzoyl chloride
All reactions and manipulations were carried out under nitro-
gen by using standard Schlenk techniques. NMR spectra
were recorded at ambient temperature on a Bruker ACF-300
FT-NMR spectrometer in CDCl3 unless otherwise stated. IR
spectra were recorded as hexane solutions, unless otherwise
stated, in solution cells with NaCl windows and 0.1 mm path-
lengths, at 1 cmϪ1 resolution. Microanalyses were carried out
by the microanalytical laboratory at the National University
of Singapore. All reagents were from commercial sources and
used as supplied. The cluster Os3(µ-H)(CO)10(µ-OH), 1, was
prepared according to the literature method.4
To a solution of 2a (74.7 mg, 85.6 µmol) in anhydrous THF (16
mL) kept at 0 ЊC was added Et3N (15 mL), followed by the
dropwise addition of benzoyl chloride (5 mL) in anhydrous
THF (14 mL). The reaction mixture was stirred for 2 h, the
solvent and volatiles removed under vacuum, and the residue
chromatographed to yield Os3(µ-H)(CO)10(µ-OCH2CH2OC-
(O)Ph), 3, as a yellow band (22.8 mg, 31%). νmax/cmϪ1 (hexane)
2111w, 2071s, 2060s, 2024vs, 2001s, 1990w (CO), 1733w (C᎐O).
᎐
1H NMR δ 7.40–8.10 (m, 5H, Ph), 4.26 (t, 2H, 2H, OCH2-
3
CH2OCOPh, JHH = 4.4 Hz), 3.93 (t, 2H, OCH2CH2OCOPh),
Ϫ12.40 (s, 1H, OsHOs). Analysis (Found): C, 22.46; H, 0.95.
Calc. for C19H10O13Os3: C, 22.44; H, 0.99%.
Syntheses
Partial oxidation of 2a to Os3(ꢀ-H)(CO)10(ꢀ-OCH2CHO), 4a
Preparation of Os3(ꢀ-H)(CO)10(ꢀ-OCH2CH2OH), 2a. A 240
mL toluene solution of the cluster 1, prepared from Os3(CO)12
(420 mg, 464 mmol), was refluxed under N2 with ethylene glycol
(5 mL) for 5 h. Removal of the solvent followed by column
chromatographic separation of the residue on silica gel using
dichloromethane–hexane (70 : 30, v/v) as eluant gave unreacted
A solution of 2a (75.2 mg, 82.4 µmol) in dichloromethane
(5 mL) was added to a stirred solution of triacetoxyperiod-
inane (146.2 mg, 344.9 µmol) in dichloromethane (5 mL) over
1 min. The reaction mixture was stirred for 6 h and then
quenched by pouring onto a solution of saturated aqueous
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Table 3 Crystal and refinement data for 2b, 2c, 2e, 3 and 6
Compound
2b
2c
2e
3
6
Empirical Formula
Formula weight
No. of reflections for final cell 7862
C13H8O12Os3
926.79
C13H8O12Os3
926.79
8192
C18H10O12Os3
988.86
8192
C19H10O13Os3
1016.87
5467
C29H21O11Os3P
1147.03
6398
Crystal system
Space group
Monoclinic
P21/c
Triclinic
P1
Monoclinic
C2/c
Triclinic
P1
Triclinic
P1
a/Å
b/Å
c/Å
α/Њ
7.5248(2)
16.6875(4)
16.1098(3)
8.9663(1)
13.9410(1)
16.6032(2)
105.225(1)
90.345(1)
98.629(1)
1977.65(3)
4
32.5756(4)
9.8496(2)
14.1537(2)
7.5496(1)
11.5398(1)
14.3430(1)
90.910(1)
93.875(1)
93.197(1)
1244.54(2)
2
9.8090(1)
10.8456(1)
16.4270(1)
104.859(1)
102.320(1)
93.160(1)
1639.04(2)
2
β/Њ
95.111(1)
92.198(1)
γ/Њ
V/Å3
2014.87(8)
4
3.055
4537.97(13)
8
2.895
Z
ρc/Mg mϪ3
3.113
19.284
2.714
15.339
2.324
11.704
µ/mmϪ1
18.928
16.819
F(000)
1640
0.36 × 0.36 × 0.18
13123
1640
0.36 × 0.28 × 0.26
15111
3536
0.44 × 0.31 × 0.24
23031
912
1052
Crystal size/mm3
Reflections collected
Independent reflections
0.465 × 0.263 × 0.150 0.180 × 0.180 × 0.036
8636
5942
10753
7404
4945
9413
3264
[R(int) = 0.0507]
0.106451–0.044451
4945/2/250
1.038
0.0466
0.1220
[R(int) = 0.0287]
0.060868–0.010223
9413/6/511
1.052
0.0405
0.1092
[R(int) = 0.0332]
0.068504–0.030565
3264/0/311
1.148
0.0252
0.0685
[R(int) = 0.0346]
0.139959–0.050690
5942/2/319
0.996
0.0484
0.1254
[R(int) = 0.0261]
0.404929–0.263592
7404/0/402
1.024
0.0373
0.0863
Max. and min. transmission
Data/restraints/parameters
Goodness-of-fit on F 2
Final R [I > 2σ(I )]
wR2 (all data)
Largest diff. peak and
1.816 and Ϫ4.380
2.227 and Ϫ1.967
0.824 and Ϫ1.043
2.201 and Ϫ2.977
1.137 and Ϫ1.065
hole e/ÅϪ3
3
NaHCO3 containing Na2S2O3 (8 mL). The aqueous layer
was decanted off, brine solution (≈8 mL) was added, and the
dichloromethane layer separated and dried over MgSO4.
Removal of the solvent followed by TLC of the residue gave
one major yellow band which yielded unreacted 1 (38.0 mg,
50%) and Os3(µ-H)(CO)10(µ-OCH2CHO), 4a (37.2 mg, 50%).
νmax/cmϪ1: 2112w, 2073vs, 2061s, 2026vs, 2022vs, 2011m, 2000s,
1988m. H NMR δ 9.34 (s, 1H, CHO), 4.31 (s, 2H, OCH2),
Ϫ12.35 (s, 1H, OsHOs). Analysis (Found): C, 16.19; H, 0.73.
Calc. for C12H4O12Os3: C, 15.81; H, 0.44%.
CH2CH), 2.03 (d, 1H, OH, JHH = 2.3 Hz), Ϫ12.40 (s, 1H,
OsHOs). MS (FAB): m/z 953 (calculated for Mϩ, 954).
Cleavage reaction of 2e
A solution of 2e (10.7 mg, 10.9 µmol) in dichloromethane
(seven drops) was placed inside a Schlenk tube, followed by
addition of seven drops of concentrated hydrochloric acid.
Removal of dichloromethane and excess hydrochloric acid on a
vacuum line followed by spectroscopic analysis of the residue
showed it to contain 1-phenyl-1,2-ethanediol and Os3(µ-H)-
(CO)10(µ-Cl). 1H NMR δ 7.36 (m, 5H, Ph), 4.84 (dd, 1H,
CH(OH)Ph, 3JHH = 3.5 Hz and 8.0 Hz), 3.78 (dd, 1H, CH2OH,
1
A similar reaction between 2d (15.0 mg, 16.2 µmol) and tri-
acetoxyperiodinane (18.7 mg, 45.4 µmol) afforded unreacted
2d (6.3 mg, 42%) and Os3(µ-H)(CO)10(µ-OCH2CH2CHO), 4d
(8.5 mg, 57%). νCO/cmϪ1: 2112w, 2073vs, 2061s, 2026vs, 2022vs,
2JHH = 11.1 Hz, JHH = 3.5 Hz), 3.67 (dd, 1H, CH2OH,
3
2JHH = 11.1 Hz, 3JHH = 8.0 Hz), 2.50 (br s, 1H, –OH), 2.00 (br s,
1H, –OH) and –12.78 (s, 1H, OsHOs). νCO/cmϪ1: 2116w,
2077vs, 2068s, 2028vs, 2016s, 1991m, 1988m.
1
2011m, 2000s, 1988m. H NMR δ 9.70 (s, broad, 1H, CHO),
3.94 (t, 2H, OCH2CH2CHO, J = 5.9 Hz), 2.56 (t, 2H,
CH2CH2CHO), Ϫ12.44 (s, 1H, OsHOs). MS (FAB): m/z 928
(calculated for Mϩ, 925).
Reaction of 2a with PPh3
Reaction of 4a with PhMgBr
To a solution of 2a (55.5 mg, 63.6 µmol) in CH3CN (21 mL)
was added a solution of Me3NOؒ2H2O (7.8 mg, 70 µmol) in
CH3CN (16 mL) over 10 min. After stirring for an additional 50
min, the mixture was filtered through a short column of silica
gel. A solution of PPh3 (22.4 mg, 85.4 µmol) in CH3CN (2 mL)
was then added and the mixture stirred at room temperature
for 20 min before removal of solvent and volatiles on a vacuum
line, followed by chromatographic separation on a silica gel
column to give Os3(µ-H)(CO)9(µ-OCH2CH2OH)(PPh3), 6, as
the major product. νCO/cmϪ1: 2092m, 2053s, 2012vs, 1992w,
1975w, 1951w. 1H NMR δ 7.30–7.62 (m, aromatic), 3.74 (m, 2H,
A solution of PhMgBr in anhydrous ether (1.25 mL) was added
dropwise to a solution of 4a (86.2 mg, 94.6 µmol) in anhydrous
THF (0.5 mL) maintained at Ϫ20 ЊC, and then stirred for 2.5 h.
The reaction was then quenched with aq. HCl, extracted with
ether, and the combined ether extracts dried over MgSO4.
Removal of the ether followed by chromatographic separ-
ation of the residue gave unreacted 4a (34.5 mg, 40%) and 2e
(41.0 mg, 44%) as yellow bands.
Allylation reaction of 4a
3
µ-OCH2), 3.22 (m, 2H, CH2OH), 2.40 (t, OH, JHH = 3.0 Hz),
Allyl bromide (0.04 mL, 747.7 µmol) and indium metal (19.5
mg, 170 µmol) were stirred in a water–tetrahydrofuran mixture
(0.5 mL, 1 : 1, v/v) while a solution of 4a (147 mg, 161 µmol) in
water–tetrahydrofuran (1.5 mL, 1 : 2, v/v) was added. The reac-
tion was allowed to stir overnight before extracting with ether.
One major yellow band was obtained upon TLC separations of
the ether extract, which afforded Os3(µ-H)(CO)10(µ-OCH2-
2.36 (t, OH, 3JHH = 3.0 Hz), Ϫ10.19 (d, OsHOs, 2JPH = 6.9 Hz),
2
Ϫ10.96 (d, OsHOs, JPH = 6.9 Hz). 31P{1H} NMR δ 26.8 (s),
14.5 (s). Analysis (Found): C, 30.40; H, 1.83. Calc. for
C29H21O11Os3P: C, 30.37; H, 1.85%.
Crystal structure determinations
CH(OH)CH CH᎐CH ), 5, as a yellow oil (18.1 mg, 12%).
Crystals were grown by slow cooling of dichloromethane–
hexane solutions, and the selected crystals were mounted on
quartz fibres. X-Ray data were collected on a Siemens SMART
CCD system, using Mo-Kα radiation, at ambient temperatures
᎐
2
2
νCO/cmϪ1: 2109w, 2071vs, 2058s, 2022vs, 2017sh, 2000s, 1986m.
1H NMR δ 5.74 (m, 1H, CH᎐CH ), 5.13 (m, 2H, CH᎐CH ),
᎐
᎐
2
2
3.67 (m, 2H, OCH2), 3.49 (m, 1H, CHOH), 2.11 (m, 2H,
2480 J. Chem. Soc., Dalton Trans., 2001, 2476–2481

View Article Online
3 (a) S. E. Kabir, D. S. Kolwaite, E. Rosenberg, K. Hardcastle,
(293(2) K). Data were corrected for Lorentz and polarisation
effects with the SMART suite of programs,17 and for absorption
effects with SADABS.18 The final unit cell parameters were
obtained by least-squares on a number of strong reflections.
Structural solution and refinement were carried out with the
SHELXTL suite of programs.19
W. Cresswell and J. Grindstaff, Organometallics, 1995, 14, 3611; (b)
M. J. Abedin, B. Bergman, R. Holmquist, R. Smith, E. Rosenberg,
J. Ciurash, K. Hardcastle, J. Roe, V. Vazquez, C. Roe, S. Kabir, B.
Roy, S. Alam and K. A. Azam, Coord. Chem. Rev., 1999, 192, 975;
(c) B. Bergman, R. Holmquist, R. Smith, E. Rosenberg, J. Ciurash,
K. Hardcastle and M. Visi, J. Am. Chem. Soc., 1998, 120, 12818.
4 D. Roberto, E. Lucenti, C. Rovenda and R. Ugo, Organometallics,
1997, 16, 5974.
5 W. K. Leong and M. W. Lum, Acta Crystallogr., Sect. C, 1999, 55,
881.
6 (a) R. W. Broach and J. M. Williams, Inorg. Chem., 1979, 18, 314;
(b) A. J. Deeming, P. J. Manning, I. P. Rothwell, M. B. Hursthouse
and N. P. C. Walker, J. Chem. Soc., Dalton Trans., 1984, 2023; (c)
K. Burgess, B. F. G. Johnson, J. Lewis and P. R. Raithby, J. Chem.
Soc., Dalton Trans., 1982, 263.
7 F. H. Allen, O. Kennard, D. G. Wilson, L. Brammer, A. G. Orpen
and R. Taylor, J. Chem. Soc., Perkin Trans. 2, 1987, S1.
8 S. Agarwal, H. P. Tiwari and J. P. Sharma, Tetrahedron, 1990, 46,
4417.
9 K. Omura and D. Swern, Tetrahedron, 1978, 39, 1977.
10 (a) W. M. Coates and J. R. Corrigan, Chem. Ind. (London), 1969,
1594; (b) E. J. Corey and G. Schmidt, Tetrahedron Lett., 1979,
20, 399; (c) S. Czernecki, C. Georgoulis, C. L. Stevens and K.
Vijayakumaran, Tetrahedron Lett., 1985, 26, 1699.
The structure was solved by direct methods to locate the
heavy atoms, followed by difference maps for the light, non-
hydrogen atoms. Organic hydrogen atoms were placed in
calculated positions and given isotropic thermal parameters
at 1.5 times that of the C atoms to which they are attached,
except for the alkyl hydrogens in 2e, which were located by a low
angle difference map. The metal hydride positions were located
by low angle (2θ ≤ 30Њ) difference maps, except for 3 in which
the hydride was placed with the program XHYDEX.20 All
non-hydrogen atoms were given anisotropic thermal param-
eters in the final model. Cluster 2b has disorder of the OH with
the CH3 group, which were modelled with two sites of equal
occupancy together with appropriate restraints on bond and
atomic parameters. Crystal and refinement data are tabulated in
Table 3.
CCDC reference numbers 163860–163864.
See http://www.rsc.org/suppdata/dt/b1/b103800c/ for crystal-
lographic data in CIF or other electronic format.
11 See, for instance, W. Carruthers, Some Modern Methods of Organic
Synthesis, Cambridge University Press, Cambridge, 2nd edn., 1978,
pp. 343–348.
12 D. B. Dess and J. C. Martin, J. Am. Chem. Soc., 1991, 113, 7277.
13 (a) C. J. Li and T. H. Chan, Tetrahedron Lett., 1991, 32, 7017; (b)
S. Araki, H. Ito and Y. Butsugan, J. Org. Chem., 1988, 53, 1831.
14 (a) A. J. Deeming, B. F. G. Johnson and J. Lewis, J. Chem. Soc.,
1970, 897; (b) M. R. Churchill and R. A. Lashewycz, Inorg. Chem.,
1979, 18, 1926. Also checked against an authentic sample.
15 E. J. Ditzel, M. P. Gomez-Sal, B. F. G. Johnson, J. Lewis and P. R.
Raithby, J. Chem. Soc., Dalton Trans., 1987, 1623.
Acknowledgements
This work was supported by the National University of
Singapore (Research Grant No. RP 982751) and one of us
(M.W.L.) thanks the University for a Research Scholarship.
A gift of the Dess–Martin reagent from Dr Loh Teck Peng is
also gratefully acknowledged.
16 J. Banford, M. J. Mays and P. R. Raithby, J. Chem. Soc., Dalton
Trans., 1985, 1355.
17 SMART, version 4.05, Siemens Energy and Automation Inc.,
Madison, WI, USA, 1996.
18 G. M. Sheldrick, SADABS, University of Göttingen, 1996.
19 SHELXTL, version 5.03, Siemens Energy and Automation Inc.,
Madison, WI, 1996.
20 A. G. Orpen, XHYDEX, School of Chemistry, University of
Bristol, UK, 1997.
21 C. K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, 1996.
References
1 For example, A. K. Smith, in Comprehensive Organometallic
Chemistry II, ed. E. W. Abel, F. G. A. Stone and G. Wilkinson,
Elsevier, Oxford, 1995, vol. 7, ch. 13, pp. 750–751.
2 A. J. Arce, Y. De Sanctis and A. J. Deeming, J. Organomet. Chem.,
1986, 311, 371.
J. Chem. Soc., Dalton Trans., 2001, 2476–2481
2481