Reactivity of [(μ-H)Os3(CO)8{Ph2PCH2P(Ph)C 6H4}] with organic heterothiols; X-ray structures of [H(μ-H)Os3(CO)8(η2-pyS){Ph 2PCH2P(Ph)C6H4}] and [Os3(CO)8(μ-η2-pyS){Ph 2

Article abstract of DOI:10.1016/S0022-328X(00)00696-3

The reaction of [(μ-H)Os₃(CO)₈ {Ph₂PCH₂P(Ph)C⁶H⁴}] (3) with pyridine-2-thiol (pySH, C₅H₄NSH) at room temperature gave two novel clusters [(μ-H)Os₃(CO)₈(μ-pyS)(μ-dppm)] (4) and [H(μ-H)Os₃(CO)₈(η²-pyS){Ph ₂PCH₂P(Ph)C6H4}] (5) in 55 and 15% yields, respectively. Compound 4 is formed by simple oxidative addition of pySH and demetallation of the phenyl ring of dppm ligand whereas the 50-electron cluster 5 results from oxidative addition of pySH and coordination of the thiolate moiety as a chelating ligand and cleavage of one of the metal-metal bonds. The analogous reaction of 3 with pySH at 80°C gave the new compound [Os₃(CO)₈(μ-η²-pyS){Ph ₂PCH₂P(Ph)C₆H₄}] (6) in 20% yield together with 4 and 5 in 40 and 7% yields, respectively. Compound 6 contains a chelating/bridging pyS ligand and an orthometallated dppm ligand. In contrast, the reaction of 3 with pyrimidine-2-thiol (pymSH, C₄H₃N₂SH) at room temperature and at 80°C affords only the simple oxidative addition product [(μ-H)Os₃(CO)₈(μ-pymS)(μ-dppm)] (7). Compound 6 reacts with molecular hydrogen to give 5 and 4 in 20 and 10% yields, respectively. Compound 5 was converted to 6 (30%) with the formation of 3 (10%) by refluxing in heptane at 98°C. The new complexes 4, 5, 6 and 7 have been characterized by spectroscopic data together with X-ray structure determinations for 5 and 6.

Full text of DOI:10.1016/S0022-328X(00)00696-3

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 616 (2000) 157–164
Reactivity of [(m-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] with organic
heterothiols; X-ray structures of
[H(m-H)Os3(CO)8(h2-pyS){Ph2PCH2P(Ph)C6H4}] and
[Os3(CO)8(m-h2-pyS){Ph2PCH2P(Ph)C6H4}]
Shariff E. Kabir a, K.M. Abdul Malik b,*, Elias Molla a, M. Abdul Mottalib a
a Department of Chemistry, Jahangirnagar Uni6ersity, Sa6ar, Dhaka-1342, Bangladesh
b Department of Chemistry, Cardiff Uni6ersity, PO Box 912, Park Place, Cardiff CF10 3TB, UK
Received 16 June 2000; received in revised form 17 September 2000
Abstract
The reaction of [(m-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] (3) with pyridine-2-thiol (pySH, C5H4NSH) at room temperature gave
two novel clusters [(m-H)Os3(CO)8(m-pyS)(m-dppm)] (4) and [H(m-H)Os3(CO)8(h2-pyS){Ph2PCH2P(Ph)C6H4}] (5) in 55 and 15%
yields, respectively. Compound 4 is formed by simple oxidative addition of pySH and demetallation of the phenyl ring of dppm
ligand whereas the 50-electron cluster 5 results from oxidative addition of pySH and coordination of the thiolate moiety as a
chelating ligand and cleavage of one of the metalꢀmetal bonds. The analogous reaction of 3 with pySH at 80°C gave the new
compound [Os3(CO)8(m-h2-pyS){Ph2PCH2P(Ph)C6H4}] (6) in 20% yield together with 4 and 5 in 40 and 7% yields, respectively.
Compound 6 contains a chelating/bridging pyS ligand and an orthometallated dppm ligand. In contrast, the reaction of 3 with
pyrimidine-2-thiol (pymSH, C4H3N2SH) at room temperature and at 80°C affords only the simple oxidative addition product
[(m-H)Os3(CO)8(m-pymS)(m-dppm)] (7). Compound 6 reacts with molecular hydrogen to give 5 and 4 in 20 and 10% yields,
respectively. Compound 5 was converted to 6 (30%) with the formation of 3 (10%) by refluxing in heptane at 98°C. The new
complexes 4, 5, 6 and 7 have been characterized by spectroscopic data together with X-ray structure determinations for 5 and 6.
© 2000 Published by Elsevier Science B.V. All rights reserved.
Keywords: Triosmium; Pyridine-2-thiol; Pyrimidine-2-thiol, Carbonyl; Crystal structure
1. Introduction
interesting area of research. Pyridine-2-thione and
pyrimidine-2-thione give rise to an extensive chemistry
with considerable structural diversity [16], since as neu-
tral ligands they can in principle coordinate both in the
The chemistry of transition metal clusters with hete-
rocyclic organic molecules has attracted considerable
attention in recent years [1–7]. The presence of het-
eroatoms such as sulfur [8–10] and nitrogen [11–13]
introduces novel reactivities, and this frequently stabi-
lizes the metal cluster framework with respect to degra-
dational fragmentation when subjected to forcing
reaction conditions. Thus the reactivity of organic hete-
rocyclic molecules containing nitrogen and sulfur atoms
such as thioamide [7], pyridine-2-thiol [14], and pyrim-
idine-2-thione [15] towards metal carbonyl clusters is an
* Corresponding author. Tel.: +44-29-2087-4950; fax: +44-29-
2087-4030.
E-mail address: malikka@cardiff.ac.uk (K.M. Abdul Malik).
Fig. 1. Different co-ordination modes of pyridine-2-thione and pyrim-
idine-2-thione.
0022-328X/00/$ - see front matter © 2000 Published by Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00696-3

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S.E. Kabir et al. / Journal of Organometallic Chemistry 616 (2000) 157–164
the free thioamides. Decarbonylation of these com-
plexes either thermally, or by the reaction with
trimethylamineoxide, give [(m-H)Os3(CO)9L] (2) which
exist as two isomers in solution as depicted in Scheme
1.
Recently we described [30] the reactions of the unsat-
urated triosmium cluster [(m-H)Os3(CO)8{Ph2PCH2P-
(Ph)C6H4}] (3) with mono thiols such as ethanethiol,
propane-2-thiol and thiophenol, and observed a re-
markable control of the steric bulk of the thiols on
product formation. As part of on going studies of the
reactivity of trimetallic clusters with thiols, we now
report on the reactions of 3 with pyridine-2-thiol
(pySH) and pyrimidine-2-thiol (pymSH).
Scheme 1.
2. Results and discussion
Treatment of [(m-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}]
(3) with two equivalents of pySH in dichloromethane or
benzene at room temperature gives the new clusters
[(m-H)Os3(CO)8(m-pyS)(m-dppm)] (4) (55%) and [H(m-
H)Os3(CO)8(h2-pyS){Ph2PCH2P(Ph)C6H4}] (5) (15%)
(Scheme 2). Both these compounds have been charac-
terized by elemental analysis, infrared, 1H- and 31P-
NMR spectroscopic data together with a crystal
structure analysis for 5.
The infrared spectrum of 4 in the carbonyl region is
very similar to that of [(m-H)Os3(CO)8(m-SEt)(m-dppm)]
[30] and [(m-H)Os3(CO)8(m-SPh)(m-dppm)] [30] suggest-
ing that they have similar structures. The 1H-NMR
spectrum of 4 shows a multiplet for the aromatic pro-
tons at l 6.91–8.45 and two sets of multiplets at l 5.40
and 4.77 for the methylene protons of the dppm ligand.
The high field doublet at l −15.90 (J=30.2 Hz) is
assigned to the bridging hydride which is coupled to
only one phosphorus nucleus. The 31P{1H}-NMR spec-
trum contains two doublets at l −23.4 and −24.7
(J=41.8 Hz) due to nonequivalent and mutually cou-
pled 31P nuclei. The mass spectrum of 4 shows molecu-
lar ion peak at m/z 1290, which fragmented by the loss
of eight CO groups. Thus based on spectroscopic data
and by analogy with the above related compounds, it is
proposed that 4 has a structure with the pyS and the
hydride ligands bridging one of the OsꢀOs edges not
spanned by the dppm ligand.
Scheme 2.
‘thione’ and in the tautomeric ‘thiol’ form
(ꢀNHꢀCꢁS X ꢀNꢁCꢀSH) [17–23]. The coordination
chemistry displayed by tautomeric ligands of this type
is also very interesting. Pyridine-2-thione [22] and
pyrimidine-2-thione [1] are known to act as monoden-
tate ligands through the sulfur atom A [17,18,23,24], as
chelating ligands through the sulfur and nitrogen atoms
B [21,25], as bridging ligands through the sulfur atom C
[15], and as bridging ligands through the nitrogen and
sulfur atoms linking two D [26], three E [15,22,27] or
four metal atoms F [14] (Fig. 1).
Pyridine-2-thione is a special case of thioamide which
reacts with [M3(CO)12] to give [(m-H)M3(CO)9(m-pyS)]
(M=Os, Ru) in which pyS acts as a five electron donor
ligand. Interestingly, [(m-H)Ru3(CO)9(m3-pyS)] ther-
mally decarbonylates to give [(m-H)Ru3(CO)7(m3-pyS)]3
which exists as a tricluster system held together sub-
stantially through the Ru3S3 ring [14]. Thioamido com-
plexes of the type [Ru2(CO)6(L)2] and [(m-H)Ru3(CO)9-
(L)] are obtained [28] when [Ru3(CO)12] reacts with the
heterocyclic thioamide, benzothiazoline-2-thione (HL).
In contrast, the reaction of HL with [Fe3(CO)12] affords
[Fe3(CO)9S2] by desulfurization of the thioamide ligand
[29]. Lewis et al. [7] investigated the reactions of a series
of heterocyclic thioamides with the lightly stabilized
cluster [Os3(CO)10(MeCN)2] and obtained the decacar-
bonyl compounds [(m-H)Os3(CO)10L] in which the
thioamido ligands are binding in the thiolate form as
depicted in 1 rather than in the thione form found for
An X-ray structure determination showed that com-
pound 5 crystallizes as a dichloromethane solvate. A
molecule of this cluster is depicted in Fig. 2 and selected
bond distances and angles are given in Table 1. The
basic structure consists of an array of three osmium
atoms with two different metalꢀmetal bonds
,
[Os(1)ꢀOs(2)=2.9412(9) A] and [Os(1)ꢀOs(3)=
,
,
3.2151(10) A]. The Os(2)···Os(3) distance [4.7521(12) A]
is too long for any significant metal–metal interaction.
One terminal metal atom [Os(3)] is associated with two

S.E. Kabir et al. / Journal of Organometallic Chemistry 616 (2000) 157–164
159
two phosphorus atoms, and a second bridge between
Os(1) and Os(3) involving one phosphorus and one
ortho-phenyl carbon atoms. Of the two hydride ligands,
one is bridging between the Os(1)ꢀOs(3) edge whilst the
other is terminally bonded with Os(2). The Os(1)ꢀOs(2)
edge, bridged by the orthometallated dppm ligand, is
considerably longer than the average metalꢀmetal bond
terminal CO ligands while the other terminal [Os(2)]
and central [Os(1)] atoms are each linked to three
terminal CO ligands. The Ph2PCH2P(Ph)C6H4 ligand
forms one bridge between Os(1) and Os(2) through the
,
[2.877(3) A] in [Os3(CO)12] [31] but close to the value of
,
[2.957(3) A] in [(m-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}-
(PiPr3)] [32]. The doubly bridged Os(1)ꢀOs(3) edge
shows marked elongation compared with the other
OsꢀOs bond, which is consistent with the fact that a
bridging hydride on a metal cluster causes significant
lengthening of the bridged metalꢀmetal edge if another
bridging ligand along the same edge does not have any
bond shortening effect [33]. Similar long metalꢀmetal
bonds were also observed in [(m-H)Os3(CO)9(m-
,
Me2PCHPMe2)] [OsꢀOs=3.104(1) A] [34], [H(m-
,
H)Os3(CO)7(m-dppm)(m-PPh2)] [OsꢀOs=3.1486(8) A]
[35] and [(m-H)Ru3(CO)7{m3-h4-P(C6H5)CHP(C6H5)-
(C6H4)}(m-dppm)] [RuꢀRu=3.205(1) A] [36]. It may be
,
mentioned here that the bridging and terminal hydrides
in 5 were obtained from difference map and are also
consistent with spectroscopic data (see below).
Fig. 2. Molecular structure of [H(m-H)Os3(CO)8(h2-pyS){Ph2PCH2P-
(Ph)C6H4}] (5) showing the atom labeling. Thermal ellipsoids are
drawn ad 50% probability level. The hydrogen atoms except those
bonded to the osmium atoms are omitted for clarity.
The pyS ligand in 5 displays a N, S chelating mode of
coordination to Os(3). This ligand donates three elec-
trons to the cluster via a two electron donor bond
involving the lone pair of electrons of N(1) and one
electron donor bond from S(1) to the same metal atom
Os(3). Such coordination modes of the heterocyclic
ligand have been observed in mononuclear complexes
[21], but to our knowledge compound 5 provides the
first example of a cluster compound containing the pyS
ligand in a purely chelating mode. The OsꢀN [2.147(8)
Table 1
,
Selected bond lengths (A) and angles (°) for 5
Bond lengths
Os(1)ꢀOs(2)
Os(1)ꢀP(1)
Os(3)ꢀC(20)
Os(3)ꢀS(1)
N(1)ꢀC(10)
Os(1)ꢀH(1)
Os(2)ꢀH(2)
PꢀC
2.9412(9) Os(1)ꢀOs(3)
3.2151(10)
2.378(2)
2.145(8)
1.713(10)
1.363(11)
1.88 a
2.379(2)
2.122(8)
2.518(3)
Os(2)ꢀP(2)
Os(3)ꢀN(1)
S(1)ꢀC(14)
1.336(11) N(1)ꢀC(14)
1.62 a
1.76 a
1.831 b
Os(3)ꢀH(1)
OsꢀC(CO)
OꢀC
1.904 b
,
,
A] and OsꢀS [2.518(3) A] bonds in the chelate in 5 are
1.147 b
slightly longer than the corresponding (average) values
,
[2.134 and 2.430 A] in monomeric [Os(CO)2(pyS)2] [37].
Bond angles
C(1)ꢀOs(1)ꢀC(3)
C(3)ꢀOs(1)ꢀC(2)
C(3)ꢀOs(1)ꢀP(1)
92.8(4)
90.6(4)
170.0(3)
C(1)ꢀOs(1)ꢀC(2)
C(1)ꢀOs(1)ꢀP(1)
C(2)ꢀOs(1)ꢀP(1)
C(3)ꢀOs(1)ꢀOs(2)
P(1)ꢀOs(1)ꢀOs(2)
C(6)ꢀOs(2)ꢀC(4)
C(6)ꢀOs(2)ꢀP(2)
C(4)ꢀOs(2)ꢀP(2)
C(5)ꢀOs(2)ꢀOs(1)
P(2)ꢀOs(2)ꢀOs(1)
C(7)ꢀOs(3)ꢀC(20)
C(7)ꢀOs(3)ꢀN(1)
C(20)ꢀOs(3)ꢀN(1)
C(8)ꢀOs(3)ꢀS(1)
N(1)ꢀOs(3)ꢀS(1)
94.9(4)
96.2(3)
92.9(3)
86.3(3)
84.70(6)
97.3(4)
91.7(3)
94.5(3)
84.4(3)
90.56(6)
90.0(4)
92.7(3)
94.2(3)
105.3(3)
65.9(2)
The spectroscopic data of 5 are in accord with the
solid state structure. The infrared spectrum of 5 shows
w(CO) absorption bands in the region characteristic of
C(1)ꢀOs(1)ꢀOs(2) 179.1(3)
1
terminal CO ligands. The H-NMR spectrum shows a
C(2)ꢀOs(1)ꢀOs(2)
C(6)ꢀOs(2)ꢀC(5)
C(5)ꢀOs(2)ꢀC(4)
C(5)ꢀOs(2)ꢀP(2)
85.2(3)
91.9(4)
95.2(4)
169.2(3)
multiplet at l 6.20–7.88 (23 H) for aromatic protons.
Another two multiplets at l 5.20 and 3.75 are at-
tributed to the methylene protons of dppm. The two
high field signals at l −9.04 (dd) and −12.30 (d) are
attributed to the terminal and bridging hydrides, re-
spectively. The terminal hydride is coupled to two
nonequivalent phosphorus atoms of the dppm ligand
and appears as a doublet of a doublet, and the bridging
hydride is coupled to only one phosphorus nucleus and
appears as a doublet. The 31P{1H}-NMR spectrum
displays two doublets at l −8.7 and −14.7 (J=64.4
Hz) which indicates that the two phosphorus nuclei are
nonequivalent.
C(6)ꢀOs(2)ꢀOs(1) 171.0(3)
C(4)ꢀOs(2)ꢀOs(1)
C(7)ꢀOs(3)ꢀC(8)
C(8)ꢀOs(3)ꢀC(20)
C(8)ꢀOs(3)ꢀN(1)
C(7)ꢀOs(3)ꢀS(1)
C(20)ꢀOs(3)ꢀS(1)
C(14)ꢀS(1)ꢀOs(3)
91.2(3)
84.4(4)
94.7(4)
170.6(3)
94.3(3)
159.8(2)
79.5(3)
C(19)ꢀC(20)ꢀC(15) 115.8(7)
C(15)ꢀC(20)ꢀOs(3) 124.6(6)
C(19)ꢀC(20)ꢀOs(3) 119.6(6)
OsꢀCꢀO
176.7 b
a Approximate values.
b Average values.

160
S.E. Kabir et al. / Journal of Organometallic Chemistry 616 (2000) 157–164
The two metalꢀmetal bonds in 6 have nearly the
same values, Os(1)ꢀOs(2)=2.9660(10) and Os(1)ꢀOs(3)
,
=2.9541(11) A, and are comparable with the Os(1)ꢀ
Os(2) bond (bridged by the orthometallated dppm lig-
and) in 5 and that in [(m-H)Os3(CO)8{Ph2PCH2P(Ph)-
C6H4}(PiPr3)] [32]. The presence of a sulfur bridge
along the non-bonding Os(1)···Os(3) edge in 6 reduces
,
this distance to 3.972 (2) A from the corresponding
,
value 4.7521(12) A in 5. Both the pyS and the or-
Scheme 3.
thometallated dppm ligands in 6 act as five-electron
donor, which results in a total of 50 valence electrons
and is consistent with the presence of only two formal
OsꢀOs bonds in the trinuclear cluster. The OsꢀSꢀOs
bridge is asymmetric with Os(1)ꢀS(1) and Os(3)ꢀS(1)
,
distances of 2.480(5) and 2.439(4) A, respectively
and Os(1)ꢀS(1)ꢀOs(3) angle of 107.7(2)°. The OsꢀS
distances in this complex are smaller than the OsꢀS
bond in 5, and close to those in other sulfur bridged
triosmium and triruthenium clusters [1,38,39]. The geo-
metry parameters in the pyS ligand in both 5 and 6 are
Table 2
,
Selected bond lengths (A) and angles (°) for 6
Bond lengths
Os(1)ꢀOs(2)
Os(1)ꢀP(1)
Os(2)ꢀN(1)
Os(3)ꢀS(1)
S(1)ꢀC(14)
N(1)ꢀC(14)
PꢀC
2.9660(10)
2.350(4)
2.126(15)
2.439(4)
1.76(2)
Os(1)ꢀOs(3)
Os(2)ꢀP(2)
Os(2)ꢀS(1)
Os(3)ꢀC(20)
N(1)ꢀC(10)
OsꢀC(CO)
OꢀC
2.9541(11)
2.332(5)
2.480(5)
2.19(2)
Fig. 3. Molecular structure of [Os3(CO)8(m-h2-pyS){Ph2PCH2P-
(Ph)C6H4}] (6) showing the atom labeling. Thermal ellipsoids are
drawn ad 50% probability level. The hydrogen atoms are omitted for
clarity.
1.35(2)
1.30(3)
1.908 a
1.846 a
1.155 a
Bond angles
C(3)ꢀOs(1)ꢀC(1)
C(1)ꢀOs(1)ꢀC(2)
C(1)ꢀOs(1)ꢀP(1)
C(3)ꢀOs(1)ꢀOs(3)
96.0(8)
97.5(8)
92.0(6)
92.8(6)
C(3)ꢀOs(1)ꢀC(2)
93.0(8)
In contrast to the reaction at room temperature
which afforded 4 and 5, the reaction of 3 with pySH
in benzene at 80°C gives the novel compound
[Os3(CO)8(m-h2-pyS){Ph2PCH2P(Ph)C6H4}] (6) in 20%
yield in addition to 4 (40%) and 5 (7%) (Scheme 3).
Compound 6 has been characterized by elemental
C(3)ꢀOs(1)ꢀP(1) 170.4(5)
C(2)ꢀOs(1)ꢀP(1) 91.1(5)
C(1)ꢀOs(1)ꢀOs(3) 91.6(6)
P(1)ꢀOs(1)ꢀOs(3)
C(1)ꢀOs(1)ꢀOs(2) 175.9(6)
P(1)ꢀOs(1)ꢀOs(2)
C(5)ꢀOs(2)ꢀC(4)
C(4)ꢀOs(2)ꢀN(1)
C(4)ꢀOs(2)ꢀP(2)
C(5)ꢀOs(2)ꢀS(1)
N(1)ꢀOs(2)ꢀS(1)
C(5)ꢀOs(2)ꢀOs(1) 88.7(6)
N(1)ꢀOs(2)ꢀOs(1) 90.8(4)
S(1)ꢀOs(2)ꢀOs(1)
C(6)ꢀOs(3)ꢀC(7)
C(6)ꢀOs(3)ꢀC(20) 91.6(8)
C(7)ꢀOs(3)ꢀC(20) 175.3(7)
C(8)ꢀOs(3)ꢀS(1)
C(20)ꢀOs(3)ꢀS(1)
C(8)ꢀOs(3)ꢀOs(1) 90.5(6)
C(20)ꢀOs(3)ꢀOs(1) 92.3(5)
C(14)ꢀS(1)ꢀOs(3) 103.6(6)
Os(3)ꢀS(1)ꢀOs(2) 107.7(2)
C(15)ꢀC(20)ꢀOs(3) 125.1(13)
C(2)ꢀOs(1)ꢀOs(3) 168.6(6)
81.81(12)
C(3)ꢀOs(1)ꢀOs(2)
C(2)ꢀOs(1)ꢀOs(2)
Os(3)ꢀOs(1)ꢀOs(2)
C(5)ꢀOs(2)ꢀN(1)
C(5)ꢀOs(2)ꢀP(2)
N(1)ꢀOs(2)ꢀP(2)
C(4)ꢀOs(2)ꢀS(1)
P(2)ꢀOs(2)ꢀS(1)
83.8(5)
86.6(6)
84.27(3)
95.2(7)
91.6(5)
173.2(4)
94.6(5)
107.0(2)
87.83(11)
94.5(8)
92.0(6)
87.3(5)
159.6(5)
66.3(4)
1
analysis, infrared, H- and 31P{1H}-NMR spectroscopy
and X-ray crystallography. The structure of 6 is shown
in Fig. 3 and selected bond distances and angles are
given in Table 2. As in 5, the molecule of 6 consists of
C(4)ꢀOs(2)ꢀOs(1) 175.6(5)
a
triangular array of osmium atoms with two
P(2)ꢀOs(2)ꢀOs(1)
C(6)ꢀOs(3)ꢀC(8)
C(8)ꢀOs(3)ꢀC(7)
C(8)ꢀOs(3)ꢀC(20)
C(6)ꢀOs(3)ꢀS(1)
C(7)ꢀOs(3)ꢀS(1)
89.53(11)
83.39(10)
90.1(9)
metalꢀmetal bonds, but in this case the open edge is
bridged by the sulfur atom of the pyS ligand to give a
nearly planar Os3S framework. The coordination of the
orthometallated dppm ligand to the three osmium
atoms is very similar in both compounds, but the
bonding mode of pyS is different. In 5, it forms only a
chelate ring with a terminal osmium atom, whereas in
6, in addition to a similar chelate, it also forms a bridge
between the terminal metal atoms. The eight CO
groups in the molecule are distributed as shown in Fig.
3.
92.3(9)
94.6(8)
89.7(8)
93.5(7)
94.7(5)
169.0(7)
80.8(5)
C(6)ꢀOs(3)ꢀOs(1) 175.1(7)
C(7)ꢀOs(3)ꢀOs(1)
S(1)ꢀOs(3)ꢀOs(1)
C(14)ꢀS(1)ꢀOs(2)
C(15)ꢀC(20)ꢀC(19) 114(2)
C(19)ꢀC(20)ꢀOs(3) 120.6(14)
85.7(7)
84.35(11)
78.8(8)
OsꢀCꢀO
175.3 a
a Average values.

S.E. Kabir et al. / Journal of Organometallic Chemistry 616 (2000) 157–164
161
converted into 4 even in refluxing heptane, suggesting
that 4 does form through the intermediacy of 5. Com-
pound 6 reacts with molecular hydrogen at one atmo-
sphere and 110°C to give 4 and 5 in 10 and 20% yields,
respectively. Compound 5 is formed by the simple
oxidative addition of one molecule of hydrogen whereas
4 results from the demetallation of phenyl ring of the
orthometallated dppm ligand. Interestingly treatment of
[(m-H)Os3(CO)8{m-Ph2PCH2P(Ph)C6H4}] 3 with pymSH
at room temperature does not give the metalꢀmetal
cleavage products analogous to 5 or 6; instead it gives
the oxidative addition product [(m-H)Os3(CO)8(m-
pymS)(m-dppm)] (7) in 75% yield (Scheme 4).
Scheme 4.
similar with only minor differences. It is noted, however,
that the CꢀS [1.76(2) A] and NꢀC(S) [1.30(3) A] distances
in 6 are, respectively, slightly longer and shorter than the
,
,
Compound 7 was characterized by elemental analysis,
infrared, mass, 1H- and 31P-NMR spectroscopic data. A
strong similarity of the infrared spectrum of 7 to that of
4 indicates that both structures are similar with the pymS
ligand being coordinated to one of the unbridged OsꢀOs
edges. The 1H-NMR spectrum contains signals at l
7.08–7.84 (m, 23H), 5.95 (m, 1H) and 4.42 (m, 1H). The
multiplets at l 5.95 and 4.42 are assigned to the methyl-
ene protons of the dppm ligand while the multiplet at l
7.08–7.84 is due to the phenyl protons of the dppm
ligand and as well as the ring protons of the heterocyclic
ligand. Strong evidence for the activation of SꢀH bond
and simultaneous bridging of the hydride and the pymS
ligands to one of the OsꢀOs edges not bridged by the
dppm ligand is provided by the 1H-NMR spectrum. The
spectrum shows, in addition to the resonances due to the
phenyl, CH2 and heterocyclic ring protons, a doublet at
l −12.87 (J=32.0 Hz) for the bridging hydride owing
to its coupling with only one phosphorus atom. The mass
spectrum of 7 confirms the stoichiometry with a molec-
ular ion peak at m/z 1290 and ions formed by stepwise
loss of eight CO groups.
In summary, the most novel aspect of the present work
is the isolation and characterization of 5 from the
reaction of 3 with pySH at ambient temperature and its
subsequent conversion to another novel compound 6 by
thermal reaction at 80°C. Both compounds 5 and 6 are
50 electron clusters with two metalꢀmetal bonds with the
pyS moiety acting as a chelating ligand through the sulfur
atom in 5 and as a m-h2-ligand in 6. Another novel aspect
of this work is the difference in reactivity of pymSH
towards 3, which afforded only the simple oxidative
addition product 7 in high yield. This difference in
reactivity may, at least in part, be due to electronic effects
and further study is needed to confirm this.
,
corresponding values [1.713(10) and 1.363(11) A] in 5.
These differences are small and statistically insignificant,
but appear to be real in view of the observed trend. It
is suggested that they reflect a slight increase and a
decrease, respectively, in the CꢀS and NꢀC(S) bond
orders in 6 compared with 5, and this is caused by the
change in coordination modes of pyS in the two com-
pounds. The lengths of both these bonds indicate appre-
ciable double bond character [40].
Attachment of the Ph2PCH2P(C6H4)Ph ligand in 6 is
similar to that in 5, although the Os(1)ꢀP(1) and
Os(2)ꢀP(2) bond lengths of 2.350(4) and 2.332(5) A are
somewhat shorter than the corresponding distances
,
,
[2.379(2) and 2.378(2) A] in 5. It is also observed that
compression of the non-bonded Os···Os axis in 6, com-
pared with 5, causes small angular variations in the
ligand. The narrowing down of the C(15)ꢀC(20)ꢀC(24)
angle in the metallated phenyl ring [115.8(7)° in 5 and
114(2)° in 6 from the expected value 120.0°] is manifested
clearly in both the compounds.
The spectroscopic properties of 6 are in accordance
with the X-ray structure. The infrared spectrum of 6 in
the carbonyl-stretching region indicates that all the CO
1
groups are terminally located. The H-NMR spectrum
shows a multiplet for aromatic protons at l 6.10–8.47
and two multiplets at l 5.87 and 4.11 due to the
methylene protons of the orthometallated dppm ligand.
The signals due to the heterocyclic ring protons are
overlapped with phenyl protons of the orthometallated
dppm ligand. The 31P{1H}-NMR spectrum displays two
doublets at l −5.86 and −15.78 indicating that the
phosphorus nuclei are nonequivalent.
In view of the fact that the structure of 6 differs from
that of 5 in the displacement of two hydride ligands, we
believe that 5 may be a precursor of 6. This was verified
by thermolysis of 5 in heptane at 98°C for 5 h, which gave
6 in 15% yield. The parent compound 3 formed by the
displacement of the heterocyclic ligand was also obtained
in 25% yield. From this observation we can conclude that
the formation of 6 in the thermal reaction of 3 with
pyridine-2-thiol takes place via the intermediate forma-
tion of 5. Furthermore, compound 5 could not be
3. Experimental
Unless stated otherwise, all reactions were carried out
under a dry nitrogen atmosphere by using standard
Schlenk techniques. Solvents were distilled from the

162
S.E. Kabir et al. / Journal of Organometallic Chemistry 616 (2000) 157–164
appropriate drying agents before use. Infrared spectra
were recorded on Shimadzu FTIR 8101
C, 35.67; H, 2.15; N, 1.26%); IR (wCO, CH2Cl2): 2051s,
2008vs, 1987m, 1977w, 1939m, 1914w; H-NMR (250
1
a
spectrophotometer. NMR spectra were recorded on a
Bruker ARX-250 spectrometer. Mass spectra were
recorded on a Varian MAT 312 mass spectrometer.
Elemental analyses were performed by the microanalyt-
ical laboratories, Institut fu¨r Anorganische und Ana-
lytische Chemie, Freiburg Universitat, Germany.
Pyridine-2-thiol and pyrimidine-2-thiol were purchased
from Aldrich and used as received. The compound
[(m-H)Os3(CO)8{m-Ph2PCH2P(Ph)C6H4}] (3) was pre-
pared according to the published procedure [41].
MHz, CDCl3): l 6.10–8.47 (m, 23H), 5.87 (m, 1H),
4.11 (m, 1H); 31P{1H}-NMR (CDCl3), l −5.8 (d,
J=67.7 Hz) −15.7(d, J=67.7 Hz); 4 (0.063 g, 40%)
and 5 (0.011 g, 7%).
3.2. Reaction of 3 with pymSH
3.2.1. At room temperature
To a CH2Cl2 solution (25 cm3) of 3 (0.075g, 0.063
mmol) was added pymSH (0.014g, 0.127 mmol) and the
reaction mixture was stirred at r.t. for 72 h. The color
of the reaction mixture was changed from green to
yellow. The solvent was removed under reduced pres-
sure and the residue chromatographed by TLC on silica
gel. Elution with hexane–CH2Cl2 (7:3, v/v) gave two
bands which yielded, in order of elution, unreacted 3
ꢀ(0.005 g) and [(m-H)Os3(CO)8(m-pymS)(m-dppm)] (7)
(0.061 g, 75%) after recrystallization from hexane–
CH2Cl2 at r.t. (Anal. Calc. for C37H26N2O8Os3P2S: C,
34.41; H, 2.03; N, 2.16. Found: C, 34.67; H, 2.18; N,
2.29%). IR (wCO, CH2Cl2): 2071vs, 2025s, 1996vs,
3.1. Reaction of
[(v-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] (3) with pySH
3.1.1. At room temperature
To a CH2Cl2 solution (20 cm3) of 3 (0.050g, 0.042
mmol) was added pySH (0.009g, 0.084 mmol) and the
reaction mixture was stirred at room temperature (r.t.)
for 72 h. The solvent was removed under reduced
pressure and the residue was subjected to TLC on silica
gel. Elution with hexane–CH2Cl2 (7:3, v/v) developed
two bands. The faster moving band gave unreacted 3
(0.012 g). The second band, after recrystallization from
hexane–CH2Cl2 at −20°C, afforded [(m-H)Os3(CO)8(m-
pyS)(m-dppm)] (4) (0.030g, 55%) as orange crystals
(Anal. Calc. for C38H27NO8Os3P2S: C, 35.37; H, 2.11;
N, 1.08. Found: C, 35.25; H, 2.08; N, 1.03%); IR (wCO,
CH2Cl2): 2070vs, 2024s, 1995vs, 1953w, 1942m, 1938w
1
1943w, 1919w; H-NMR (250 MHz, CDCl3): l 7.08–
7.84 (m, 23H), 5.95 (m, 1H), 4.42 (m, 1H), −12.87 (d,
J=32.0 Hz, 1H); 31P{1H}-NMR (CDCl3): l −23.9 (d,
J=44.2 Hz), −25.7 (d, J=44.2 Hz); MS (m/z) 1291.
3.2.2. At 80°C
1
cm−1; H-NMR (250 MHz, CDCl3):l 6.90–8.45 (m,
To a benzene solution (15 cm3) of 3 (0.100 g, 0.085
mmol) was added pymSH (0.019 g, 0.170 mmol) and
the mixture refluxed for 3 h. The solvent was removed
under reduced pressure and the residue was chro-
matographed by TLC on silica gel. Elution with hex-
ane–CH2Cl2 (7:3, v/v) gave two bands. The faster
moving band gave [Os3(CO)10(dppm)] (0.031 g, 30%).
The second band gave [(m-H)Os3(CO)8(m-pymS)(m-
dppm)] (7) (0.049 g, 45%) after recrystallization from
hexane–CH2Cl2 at −20°C.
24H), 5.49 (m, 1H), 4.77 (m, 1H), −15.90 (d, J=30.2
Hz, 1H); 31P{1H}-NMR (CDCl3): l −23.4 (d, J=
41.8 Hz), −24.7 (d, J=41.8 Hz); MS (m/z): 1290,
and [H(m-H)Os3(CO)8(h2-pyS){Ph2PCH2P(Ph)C6H4}]·
CH2Cl2 (5) (0.009 g, 15%) as pale yellow crystals (Anal.
Calc. for C39H29Cl2NO8Os3P2S: C, 34.05; H, 2.13; N,
1.02. Found: C, 34.22; H, 2.26; N, 1.12%). IR (wCO,
CH2Cl2): 2081vs, 2049s, 2020vs 2000w, 1979m, 1943w;
1H-NMR (250 MHz, CDCl3): l 6.20–7.88 (m, 23H),
5.32(s, 2H), 5.20 (m, 1H), 3.75 (m, 1H) −9.04 (dd,
J=4.0, 23.8 Hz, 1H), −12.30 (d, J=14.7 Hz, 1H);
31P{1H}-NMR (CDCl3): l −8.7 (d, J=64.4 Hz),
−14.7 (d, J=64.4 Hz). The reaction of 3 with pySH in
benzene at r.t. also gave the above products in similar
yields.
3.3. Reaction of 6 with molecular hydrogen
Hydrogen gas was bubbled through a refluxing tolu-
ene solution (20 cm3) of 6 (0.040 g, 0.031 mmol) at
110°C for 2 h. The solvent was removed under reduced
pressure and the residue was chromatographed by TLC
on silica gel. Elution with hexane–CH2Cl2 (7:3, v/v)
gave 4 (0.004 g, 10%) and 5 (0.008 g, 20%).
3.1.2. At 80°C
To a benzene solution (20 cm3) of 3 (0.145 g, 0.122
mmol) was added pySH (0.027 g, 0.243 mmol) and the
reaction mixture was heated to reflux for 3 h. A similar
chromatographic separation to that above gave
[Os3(CO)8(m-h2-pyS){Ph2PCH2P(Ph)C6H4}] (6) (0.032
g, 20%) as orange crystals after recrystallization from
CH2Cl2–hexane at −20°C (Anal. Calc. for
C38H25NO8Os3P2S: C, 35.42; H, 1.96; N, 1.08. Found:
3.4. Thermolysis of 5
A heptane solution (25 cm3) of 5 (0.050 g, 0.038
mmol) was refluxed at 98°C for 5 h. The solvent was
removed under reduced pressure and the residue chro-

S.E. Kabir et al. / Journal of Organometallic Chemistry 616 (2000) 157–164
163
4. Supplementary material
matographed by TLC on silica gel. Elution with hex-
ane–CH2Cl2 (7:3, v/v) gave 3 (0.011 g, 25%), 6 (0.007 g,
15%) and 5 (0.010 g).
Crystallographic data for both compounds have been
deposited with the Cambridge Crystallographic Data
Centre, CCDC nos. 145 566 (5) and 145 567 (6). Copies
of this information may be obtained free of charge
from the Director, CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK (fax: +44-1223-3360333) or e-mail:
3.5. X-ray crystallography
Intensity data for 5 and 6 were recorded, respectively,
on a FAST area detector and a CAD4 diffractometer
using monochromatized Mo–Ka radiation (u=0.71073
deposit@ccdc.cam.ac.uk
ac.uk).
or
http://www.ccdc.cam.
,
A). Both data sets were corrected for absorption effects
using DIFABS [42]. The structures were solved by direct
methods (SHELXS-96) [43] and refined on F2 using all
unique data (SHELXL-96) [44]. The non-hydrogen atoms
were all anisotropic. The terminal and bridging hy-
drides in 5 were located from difference map, but these
atoms were not refined. Other hydrogen atoms in both
structures were included in calculated positions (riding
model). The C6H5 rings were treated as idealized
Acknowledgements
Support of this work by the Ministry of Science and
Technology, Government of the People’s Republic of
Bangladesh, is gratefully acknowledged. We are also
grateful to Professor M.B. Hursthouse for access to the
EPSRC supported X-ray data collection Service (data
for 5).
,
hexagons [CꢀC=1.390 A and CꢀCꢀC=120.0°]. A
summary of pertinent crystallographic and experimen-
tal data for the complexes is given in Table 3.
References
Table 3
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Compound
5
6
Empirical formula
C38H27NO8Os3P2S·
CH2Cl2
1375.13
150
Monoclinic
P21/n
C
38H25NO8Os3P2S
Formula weight
Temperature (K)
Crystal system
Space group
Unit cell dimensions
1288.19
150
Monoclinic
P21/n
,
a (A)
10.364(3)
21.083(4)
18.846(4)
91.92(3)
4116(2)
4
10.389(3)
31.765(5)
11.989(2)
113.98(2)
3615.2(14)
4
,
b (A)
,
c (A)
i (°)
3
,
V (A )
Z
v(Mo–Ka) (mm−1
Crystal size (mm)
)
9.549
10.720
0.08×0.06×0.06
yellow/prism
1.93–25.10
0.40×0.28×0.22
red/prism
2.19–25.10
Crystal color/shape
q range for data
collection (°)
Reflections collected 16587
Unique reflections 6126 (0.0728)
(Rint
7028
6403 (0.0452)
)
Refinement method
Full-matrix
Full-matrix
least-squares on F2 least-squares on F2
Data/restraints/
parameters
Goodness-of-fit on
F2
Final R1/wR2 indices R1=0.0604/0.0627
(all data)
6126/18/469
6403/72/442
1.030
0.992
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R1=0.0548/0.1589
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[I\2|(I)]
R1=0.0366/0.0587
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