A comparative study of the reactivity of the lightly stabilized cluster [Os3(CO)8{μ3-Ph2PCH2P(Ph)C 6H4}(μ-H)] towards tri(2-thienyl)-,tri(2-furyl)- and triphenyl-phosphine

Article abstract of DOI:10.1016/j.jorganchem.2013.08.027

Reactions of the lightly stabilized triosmium cluster [Os ₃(CO)₈{μ₃-Ph₂PCH ₂P(Ph)C₆H₄}(μ-H)] with tri(2-thienyl) phosphine (PTh₃) and tri(2-furyl)phosphine (PFu₃) are described and compared to analogous reactions with PPh₃. At room temperature, a number of products are isolated: [Os₃(CO) ₁₀(μ-dppm)] from CO addition, [Os₃(CO) ₈(PR₃){μ₃-Ph₂PCH ₂P(Ph)C₆H₄}(μ-H)] from phosphine addition, [Os₃(CO)₉(PR₃)(mdppm)] from phosphine and CO addition and [Os₃(CO)₈(PR3)₂(μ-dppm)] from addition of two equivalents of phosphine. The latter are shown by NMR and X-ray diffraction to exist as 1,2-isomers, whereby one phosphine is bound to the non-dppm-substituted center and the second shares an osmium atom with one end of the diphosphine. Heating 1,2-[Os₃(CO)₈(PTh ₃)₂(μ-dppm)] at 100 °C results in its clean isomerization to the 1,1-isomer in which both monodentate phosphines are located on the same osmium atom. Prolonged heating of [Os₃(CO) ₈(PR₃)₂(μ-dppm)] (R = Th, Ph) at 110 °C gives [Os₃(CO)₉(PR₃)(mdppm)] and the new lightly stabilized clusters [Os₃(CO)₇(PR ₃){μ₃-Ph₂PCH₂P(Ph)C ₆H₄}(μ-H)], the latter being formed by loss of phosphine and CO with concurrent metalation of a phenyl ring. Heating [Os ₃(CO)₈(PFu₃)₂(μ-dppm)] at 110 °C gives [Os₃(CO)₉(PFu₃)(μ-dppm)] together with the carbonphosphorus bond cleavage products [Os ₃(CO)₇(μ-PFu₂)(μ₃- η²-C₄H₂O)(μ-H)(μ-dppm)] and [Os ₃(CO)₇(μ-PFu₂)(μ₃- η²-C₆H₃CH₃)(μ-H)(μ-dppm)]. All new compounds were characterized by analytical and spectroscopic techniques together with single crystal X-ray diffraction analysis of nine clusters. Density functional theory (DFT) calculations have been carried out on isomers of [Os₃(CO)₈(PR₃)₂(μ-dppm)] in order to understand the observed isomer ratios.

Full text of DOI:10.1016/j.jorganchem.2013.08.027

Journal of Organometallic Chemistry 751 (2014) 399e411
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
A comparative study of the reactivity of the lightly stabilized cluster
[Os3(CO)8{m3-Ph2PCH2P(Ph)C6H4}(
m-H)] towards tri(2-thienyl)-,
tri(2-furyl)- and triphenyl-phosphine
Arun K. Raha a, Md. Nazim Uddin a, Shishir Ghosh a b, Abdur R. Miah a,
,
,
Michael G. Richmond c, Derek A. Tocher b, Ebbe Nordlander d, Graeme Hogarth b
*
,
,
Shariff E. Kabir a
*
a Department of Chemistry, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh
b Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
c Department of Chemistry, University of North Texas, 1155 Union Circle, Box 305070, Denton, TX 76203, USA
d Inorganic Chemistry Research Group, Chemical Physics, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-22100 Lund,
Sweden
a r t i c l e i n f o
a b s t r a c t
Article history:
Reactions of the lightly stabilized triosmium cluster [Os3(CO)8{m3-Ph2PCH2P(Ph)C6H4}(m-H)] with tri(2-
Received 28 May 2013
Received in revised form
9 August 2013
thienyl)phosphine (PTh3) and tri(2-furyl)phosphine (PFu3) are described and compared to analogous
reactions with PPh3. At room temperature, a number of products are isolated: [Os3(CO)10 -dppm)] from
CO addition, [Os3(CO)8(PR3){m3-Ph2PCH2P(Ph)C6H4}( -H)] from phosphine addition, [Os3(CO)9(PR3)(
dppm)] from phosphine and CO addition and [Os3(CO)8(PR3)2( -dppm)] from addition of two equivalents
(
m
m
m-
Accepted 12 August 2013
m
of phosphine. The latter are shown by NMR and X-ray diffraction to exist as 1,2-isomers, whereby one
phosphine is bound to the non-dppm-substituted center and the second shares an osmium atom with
Keywords:
Triosmium
Phosphines
Addition reactions
Isomerization
one end of the diphosphine. Heating 1,2-[Os3(CO)8(PTh3)2(m
-dppm)] at 100 ꢀC results in its clean
isomerization to the 1,1-isomer in which both monodentate phosphines are located on the same osmium
atom. Prolonged heating of [Os3(CO)8(PR3)2(
dppm)] and the new lightly stabilized clusters [Os3(CO)7(PR3){m3-Ph2PCH2P(Ph)C6H4}(m-H)], the latter
m
-dppm)] (R ¼ Th, Ph) at 110 ꢀC gives [Os3(CO)9(PR3)(
m-
Carbon-phosphorus bond cleavage
DFT studies
being formed by loss of phosphine and CO with concurrent metalation of a phenyl ring. Heating
[Os3(CO)8(PFu3)2( -dppm)] together with the carbon-
-dppm)] at 110 ꢀC gives [Os3(CO)9(PFu3)(
phosphorus bond cleavage products [Os3(CO)7( -PFu2)(m3 -H)( -dppm)] and [Os3(CO)7(
2-C4H2O)(
PFu2)(m3 -H)( -dppm)]. All new compounds were characterized by analytical and spec-
2-C6H3CH3)(
troscopic techniques together with single crystal X-ray diffraction analysis of nine clusters. Density
m
m
m
-
h
m
m
m-
-
h
m
m
functional theory (DFT) calculations have been carried out on isomers of [Os3(CO)8(PR3)2(
order to understand the observed isomer ratios.
m-dppm)] in
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
cluster [Os3(CO)8{m3-Ph2PCH2P(Ph)C6H4}(m-H)](1)[11], firstprepared
by Smith and coworkers upon decarbonylation of [Os3(CO)10(m-
The high reactivity associated with electronic and coordinative
unsaturation in mononuclear transition metal complexes has been
widely exploited in developing novel chemical behavior and in
catalysis. In comparison, despite the widespread interest in cluster
chemistry [1] the number of unsaturated low-valent clusters is
extremely limited [2e14]. Amongst the most studied examples of
dppm)], is not formally unsaturated but it behaves in this way as the
relatively weak interaction of the orthometalated phenyl group with
the triosmium center is easily removed. Consequently, 1 has been
shown to have a rich chemistry [12,13], which is dominated by ligand
addition rather than carbonyl substitution. For example, it undergoes
facile and reversible carbonylation at 25 ꢀC to afford saturated
electronically unsaturated clusters is [Os3(CO)10(m-H)2] [10], whose
[Os3(CO)9{m3-Ph2PCH2P(Ph)C6H4}(m-H)] (3) which in turn adds
unsaturation derives from its 46e count. The diphosphine-substituted
furtherCOtoregeneratetheparentcluster2(Scheme1)[11]. Recently,
Hall, Richmond and coworkers have investigated these processes in
some detail [14]. Their results show that carbonylation of 1 proceeds
* Corresponding authors.
via an intermediate [Os3(CO)8{m-Ph2PCH2P(Ph)C6H4}(m-H)] (A), in
E-mail address: skabir_ju@yahoo.com (S.E. Kabir).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.08.027

400
A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
Ph
P
2 P
(CO)3
Os
Ph2
P
(OC)
4Os
CO
H
Ph
Os
P
Os
Os(CO)3
(OC)3
(CO)3
Ph2
Os
2
B
25 oC, 2d
(CO)3
110 oC
- 2CO
CO
Ph
P
2 P
Ph
P
2 P
25 oC
Ph
Ph
CO, 2h
(CO)
Os
Os
(OC)3
Os
Os(CO)3
(OC)3
3
110 oC
4 h
H
Os
H
Os
(CO)2
(CO)3
1
3
CO
Ph
P
Ph
2 P
(CO)
Os
Os
(OC)3
3
H
Os
A
(CO)2
Scheme 1.
which an osmium-carbon bond involving the orthometalated phenyl
moiety of the dppm ligand is broken, and a subsequent (rate-deter-
mining) associative step involving the addition of CO to
dppm)] (2), [Os3(CO)8(PR3){m3-Ph2PCH2P(Ph)C6H4}(
m-H)] (4e6),
[Os3(CO)9(PR3)( -dppm)] (7e9) and [Os3(CO)8(PR3)2( -dppm)] (10e
m
m
12) (Scheme 2). Smith and coworkers previously reported that re-
action of 1 with ca. one equivalent of PPh3 gives 2, 6 and 11, while 9
has been prepared by Johnson, Lewis and coworkers from the reac-
the unsaturated intermediate, yielding [Os3(CO)9{
C6H4}( -H)] (3). Further carbonylation of 3 then proceeds via a
reductive coupling with formation of [Os3(CO)9( -dppm)] (B) as an
intermediate, a process which proceeds via an agostic intermediate,
followed by two discrete -aryl complexes (Scheme 1) [14].
m-Ph2PCH2P(Ph)
m
m
tion between [Os3(CO)9(NCMe)(m-dppm)] and PPh3 [13d,18] Cluster
2 results from addition of two molecules of CO to 1, with the CO
presumably originating from cluster degradation. The characteriza-
tion and mode of formation of each of the other product types is
discussed separately in the following sections.
p
Phosphines are widely used as ligands in transition metal-
catalyzed reactions since they offer a wide variety of stereo-
electronic properties that can substantially influence the course of a
catalyzed reaction. One of the most widely utilized is triphenyl-
phosphinewhich hasbeenreported toreactsmoothly with1 to afford
2.2. Phosphine addition products [Os3(CO)8(PR3){m3-Ph2PCH2P(Ph)
C6H4}(m-H)] (4e6)
[Os3(CO)8(PPh3){m3-Ph2PCH2P(Ph)C6H4}(m-H)] and [Os3(CO)8(PPh3)2
(
m
-dppm)] [13d]. Over the past decade the chemistry of tri(2-furyl)
Clusters 4e6 are adducts of 1 and PR3. The PPh3 complex 6 has
previously been spectroscopically characterized [13d] and data for
4 and 5 are similar. The 31P{1H} NMR spectrum of each displays a
pair of doublets, assigned to the dppm ligand, and a singlet for the
PR3 ligand. The absence of coupling between the two phosphines
suggests that either they are bound to different metal atoms or two
phosphorus atoms bound to the same osmium lie cis to one
another. Each cluster has a high field resonance in its 1H NMR
phosphine (PFu3) [15,16] and tri(2-thienyl)phosphine (PTh3) [17] has
been developed. Sterically they are akin to PPh3; however, the
electron-withdrawing nature of the 2-heteroaryl rings makes them
poorer s-donors than PPh3 [17m]. This has been exploited in certain
catalytic reactions, with PFu3-containing catalysts often being more
active than traditional PPh3-based catalysts [16]. One aspect of our
recent work has been a comparison of these three ligands in similar
chemical systems [15cef,17geh] and herein we focus on an investi-
gation of the comparative reactivity of the three phosphines towards
lightly stabilized 1.
spectrum indicative of a bridging hydride (
d
ꢁ18.1 for 4; e18.4 for
5; e15.9 for 6). In order to fully elucidate the structures we have
carried out an X-ray diffraction study of 5, the results of which are
summarized in Fig. 1. The structure of 5 is very similar to
2. Results and discussion
[Os3(CO)8(PPri3){m3-Ph2PCH2P(Ph)C6H4}(
m-H)] [13d] and contains a
triangle of osmium atoms with three distinct osmiumeosmium
bond distances [Os(1)dOs(2) 2.8961(6), Os(1)dOs(3) 2.8569(7)
and Os(2)dOs(3) 3.0883(6) A] the longest being spanned by the
hydride (located and refined in the structural analysis). The PFu3
ligand occupies an equatorial coordination site on Os(2), while the
diphosphine is axially coordinated to Os(2) and Os(1) which
2.1. Reaction of [Os3(CO)8{m3-Ph2PCH2P(Ph)C6H4}(
PR3 (R ¼ Th, Fu, Ph)
m-H)] (1) with
ꢀ
Treatment of 1 with two equivalents of the requisite phosphine at
25 ꢀC in dichloromethane gave four product types; [Os3(CO)10
(m-

A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
401
Ph
P
2 P
Ph
(CO)
Os
3Ph2
P
PR3
RT
(OC)4 Os
(CO)
Os
Os
(OC)3
3
Os
P
H
Os
(CO)3 Ph2
(CO)2
2
1
PTh3 (6%)
PFu3 (6%)
PPh3 (11%)
+
Ph
P
2 P
CO
Os
Ph
OC
(CO)
Os
3Ph2
P
+
(CO)
Os
Os
(OC)3
3
R3P
CO
Os
P
H
Os(CO)2
PR3
(CO)3 Ph2
7, R = Th (11%)
8, R = Fu (8%)
9, R = Ph (19%)
4, R = Th (13%)
5, R = Fu (12%)
6, R = Ph (29%)
CO
CO
R3P
OC
Fu3P
Fu3P
(CO)
(CO)3
3Ph2
Ph2
P
Os
Os
P
Os
Os
+
CO
Os
CO
CO
Os
P
P
(CO)3 Ph2
Ph2
R3P
CO
12, (66%)
10, R = Th (54%)
11, R = Ph (24%)
Scheme 2.
facilitates coordination of the C6H4 moiety to Os(3). The P(2)-Os(2)-
P(3) bond angle of 94.96(6)o accounts for the lack of coupling
between these phosphorus atoms. In [Os3(CO)8(PPri3){m3-Ph2
that for 9 and also other complexes of the type [Os3(CO)9L(m-
dppm)] [L ¼ P(OMe)3, PHPh2] [18,19]. Each 31P{1H} NMR spectrum
consists of a pair of doublets attributed to the diphosphine and a
singlet for the monodentate phosphine, while all 1H NMR spectra
contain a triplet in the aliphatic region assigned to the methylene
protons of the dppm ligand. We have determined the crystal
structures of both 7 and 9, which are shown in Figs. 2 and 3,
respectively. Both are as expected; all phosphorus atoms lie in the
equatorial plane and the gross structural features are similar to
PCH2P(Ph)C6H4}(m-H)], the osmiumephosphorus bonds sharing
ꢀ
the same osmium atom [2.442(7) and 2.411(8) A] are significantly
ꢀ
longer than the third [2.334(8) A] which Smith attributed to the
extra electron-density on this osmium atom due to the presence of
the PPri3 ligand [13d]. In 5, the osmiumephosphorus bond
involving P(2) of the diphosphine ligand and Os(2) is significantly
ꢀ
ꢀ
longer [2.427(2) A] than the others [2.352(2) and 2.332(2) A]. These
differences may be a result of the better -acceptor ability of PFu3,
while in contrast PPri3 is a good
-donor ligand. By analogy to the
those of [Os3(CO)9(PHPh2)(m-dppm)] [19] and [Os3(CO)10(m-dppm)]
p
[20]. It seems likely that 7e9 result from the intermediate forma-
tion of 4e6, followed by carbonyl addition, a process in which the
monodentate phosphine also migrates to another osmium center.
In a separate experiment we have shown that 6 reacts with CO to
afford 9 as one of the products. This transformation is probably in
competition with phosphine addition to 4e6 (see below), with the
actual product distribution governed by the relative amounts of
free CO and phosphine present in solution.
s
carbonylation of 1 that has been studied experimentally and
computationally [14] (vide supra), it is likely that the phosphine
adducts 4e6 are formed in a similar fashion to 3; that is via the
isomeric mono-metalated intermediate [Os3(CO)8{m-Ph2PCH2P(Ph)
C6H4}( -H)] (A) (Scheme 1).
m
2.3. Phosphine and carbonyl addition products [Os3(CO)9(PR3)(m-
dppm)] (7e9)
2.4. Double phosphine addition products [Os3(CO)8(PR3)2(m-dppm)]
(10e12)
Clusters 7e9 formally result from addition of both CO and
phosphine to 1, followed by carbon-hydrogen bond formation. The
PPh3 complex, 9, has previously been reported by Johnson, Lewis
and coworkers [18]. Spectroscopic data for 7e8 are in accord with
The fourth cluster type, and the major product in the case of all
three phosphines, is [Os3(CO)8(PR3)2( -dppm)] (10e12) which
formally result from addition of two equivalents of phosphine to 1
m

402
A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
Fig. 3. ORTEP diagram of the molecular structure of [Os3(CO)9(PPh3)(m-dppm)] (9),
Fig. 1. ORTEP diagram of the molecular structure of [Os3(CO)8(PFu3){m3-Ph2
PCH2P(Ph)C6H4}( -H)] (5), showing 50% probability thermal ellipsoids. Ring hydrogen
showing 50% probability thermal ellipsoids. Rinꢀg hydrogen atoms are omitted for
m
ꢀ
clarity. Selected bond distances (A) and angles( ): Os(1)dOs(2) 2.8768(4), Os(1)d
ꢀ
ꢀ
atoms are omitted for clarity. Selected bond distances (A) and angles( ): Os(1)dOs(2)
2.8961(6), Os(1)dOs(3) 2.8569(7), Os(2)dOs(3) 3.0883(6), Os(1)dP(1) 2.352(2),
Os(2)dP(2) 2.4267(19), Os(2)dP(3) 2.3316(18), Os(3)dOs(1)dOs(2) 64.931(10),
Os(1)dOs(2)dOs(3) 56.921(15), Os(1)dOs(3)dOs(3) 58.148(15), P(3)dOs(2)dOs(3)
111.81(5), C(4)dOs(2)dP(3) 101.1(2), P(3)dOs(2)dP(2) 94.96(6), P(1)dOs(1)dOs(3)
85.32(5), P(1)dOs(1)dOs(2) 86.81(5), C(6)dOs(3)dC(12) 89.2(3), C(12)dOs(3)d
Os(1) 91.6(2), P(1)dC(10)dP(2) 107.5(4).
Os(3) 2.9149(5), Os(2)dOs(3) 2.8871(4), Os(1)dP(1) 2.3349(11), Os(2)dP(2)
2.3311(11), Os(3)dP(3) 2.3560(11), Os(2)dOs(1)dOs(3) 59.796(6), Os(1)dOs(2)d
Os(3) 60.757(10), Os(2)dOs(3)dOs(1) 59.447(10), P(3)dOs(3)dOs(1) 102.82(3),
P(3)dOs(3)dOs(2) 160.89(3), C(7)dOs(3)dP(3) 99.94(15), C(8)dOs(3)dP(3)
90.84(15), P(1)dC(10)dP(2) 112.1(2).
have determined the crystal structures of 10 and 12, the results of
which are shown in Figs. 4 and 5, respectively. For 10 there are
two independent triosmium clusters (and three molecules of
dichloromethane) in the asymmetric unit.
with concomitant carbonehydrogen bond formation. Two isomeric
forms are seen (Chart 1), and these are denoted as the 1,1- and 1,2-
isomer. Smith and coworkers previously found that PPh3 afforded
only the 1,2-isomer, whereas other phosphines and phosphites
gave the 1,1-isomer [13d]. With P(OMe)3 both isomers were formed
and could be separated by TLC, and the X-ray structure of the 1,1-
isomer was reported. The same authors also reported the X-ray
In the solid state, 10 exists as the 1,2-isomer while 12 is a 1,1-
isomer. Akin to the situation for 11, [Os3(CO)8{P(OMe)3}2(
m-
dppm)] [13d] and [Os3(CO)8(PHPh2)2( -dppm)] [19], all phos-
m
phorus atoms in both 10 and 12 occupy equatorial coordination
sites. Spectroscopic data for non-crystalline samples of 10 showed
structure of 1,2-[Os3(CO)8(PPh3)2(
previously shown that [Os3(CO)8(PHPh2)2(
[19]. In order to confirm the nature of the different isomers, we
m-dppm)] (11) [13d] and we have
the presence of both isomers in solution (Scheme 3). Thus, the 31
P
m-dppm)] is a 1,1-isomer
{1H} NMR spectrum displays two sets of resonances in an approx-
imate 5:1 ratio. The 1,2-isomer (10a) is the major form character-
ized by signals at ꢁ20.7 (dd, JPP ¼ 50.2, 9.2 Hz), e27.3 (d,
JPP ¼ 50.2 Hz), e39.3 (d, JPP ¼ 9.2 Hz) and ꢁ51.8 (s) ppm due to the
four non-equivalent phosphorus atoms, while the minor 1,1-isomer
(10b) appears as two singlets at ꢁ29.1 and ꢁ40.8 ppm. In contrast,
spectroscopic data for 12 show that only the solid-state structure
(1,1-isomer) exists in solution, being observed as two equal in-
tensity singlets. We have carried out VT NMR studies of both 10 and
11 in d8-toluene. No significant changes were seen in the 31P NMR
spectrum of 1,2-[Os3(CO)8(PPh3)2(m-dppm)] (11) upon warming to
80 ꢀC. Above this temperature, the bright yellow solution lightened
and a number of new resonances appeared due to irreversible
changes resulting from loss of PPh3 (see following section). Heating
a sample of pure 1,2-[Os3(CO)8(PTh3)2(m
-dppm)] (10a) to 80 ꢀC led
to no significant change; however, between 80 and 100 ꢀC, the
disappearance of 10a was observed with concomitant formation of
the 1,1-isomer 10b. Scheme 3 illustrates this transformation.
Maintaining this sample at 100 ꢀC for several hours led to the
appearance of a number of new resonances associated with phos-
phine loss and secondary rearrangement products (see following
section).
In order to further probe the relative stability of 1,1- and 1,2-
isomers of 10e12, we have performed density functional theory
(DFT) calculations on both sets of isomers. Fig. 6 shows the opti-
mized structures for 10a and 10b, where the 1,2-isomer is 4.8 kcal/
mol lower in energy than the 1,1-isomer. The ligand disposition in
the optimized structure of 10a agrees nicely with the solid-state
structure that is exhibited in Fig. 4. On the basis of the
Fig. 2. ORTEP diagram of the molecular structure of [Os3(CO)9(PTh3)(
m-dppm)] (7),
showing 50% probability thermal ellipsoids. Ring hydrogen atoms are omitted for
ꢀ
ꢀ
clarity. Selected bond distances (A) and angles( ): Os(1)dOs(2) 2.9141(4), Os(1)dOs(3)
2.8829(3), Os(2)dOs(3) 2.8856(4), Os(1)dP(3) 2.3345(12), Os(2)dP(2) 2.3370(11),
Os(3)dP(1) 2.3242(11), Os(3)dOs(1)dOs(2) 59.703(8), Os(3)dOs(2)dOs(1)
59.610(6), Os(1)dOs(3)dOs(3) 60.687(9), P(3)dOs(1)dOs(2) 100.42(3), P(3)dOs(1)d
Os(3) 159.03(3), C(2)dOs(1)dP(3) 104.26(15), C(1)dOs(1)dP(3) 91.30(14), P(1)d
C(10)dP(2) 111.6(2).

A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
403
thermodynamically less stable isomer 10b forms is far from clear.
We have kinetically and computationally investigated the isomer-
ization behavior of related phosphines at Os3(CO)10(PP) clusters
(where PP ¼ diphosphine) [21]. In these examples, the isomeriza-
tion was well-behaved and does not involve the dissociation of
the diphosphine ligand from the cluster. In the case of the
Os3(CO)8(PR3)2(dppm) clusters investigated in this study, no
attempt has been made to study this isomerization process by DFT
because of the complexity of the reaction which is likely to proceed
via the loss of a monodentate PR3 ligand, followed by ligand capture
at the putative unsaturated cluster Os3(CO)8(PR3)(dppm).
The geometry of cluster 12 was subjected to DFTanalysis and the
optimized structure (not shown) was consistent with the solid-
structure structure. The corresponding 1,2-isomer based on 12
was also optimized and the disposition of the ancillary ligands
about the cluster polyhedron paralleled the DFT structure
computed for 10a. The energy difference for the two PFu3-based
clusters is small (
D
G ¼ 0.8 kcal/mol) and favors that of the crys-
tallographically observed isomer. While the ground-state energy
difference between the two isomers is small, the activation barrier
is assuredly much greater and no equilibration of the two isomers is
expected at room temperature.
Fig. 4. ORTEP diagram of the molecular structure of one of the unique molecules of
[Os3(CO)8(PTh3)2(
m
-dppm)] (10), showing 50% probability thermal ellipsoids. Riꢀng
ꢀ
hydrogen atoms are omitted for clarity. Selected bond distances (A) and angles( ):
Os(1)dOs(2) 2.8882(4), Os(1)dOs(3) 2.9128(5), Os(2)dOs(3) 2.9112(4), Os(1)dP(1)
2.3269(17), Os(2)dP(2) 2.3170(16), Os(3)dP(3) 2.3196(17), Os(2)dP(4) 2.3091(16),
Os(2)dOs(1)dOs(3) 60.242(8), Os(1)dOs(2)dOs(3) 60.298(11), Os(2)dOs(3)dOs(1)
59.461(11), P(3)dOs(3)dOs(1) 97.51(4), P(3)dOs(3)dOs(2) 156.97(4), C(7)dOs(3)d
P(3) 92.1(2), P(4)dOs(2)dP(2) 108.09(6), C(4)dOs(2)dP(4) 92.1(2), P(4)dOs(2)d
Os(1) 159.42(4), P(4)dOs(2)dOs(3) 99.53(4), P(1)dC(65)dP(2) 116.7(3).
2.5. Thermolysis of [Os3(CO)8(PR3)2(m-dppm)] (10e11): phosphine
loss and carbonehydrogen bond activation
From the variable temperature (VT) NMR studies discussed
above, we were aware that the bis(phosphine) complexes 10e11
were unstable at higher temperatures. In order to probe this
behavior, we heated 10e11 independently in toluene which fur-
nished two products in each case (Scheme 4). The major product
found in both reactions was [Os3(CO)9(PR3)(m-dppm)] (7 and 9),
resulting from phosphine substitution by CO, while the second
products were the new lightly stabilized clusters [Os3(CO)7(PR3)
free-energy difference between 10a and 10b, a Keq value of 3 ꢂ 10ꢁ4
is computed, and this is in concert with the experimental data and
the observation of only 10a in the initial synthesis. While heating
10a furnishes 10b through the formal migration of a single PTh3
ligand about the cluster polyhedron, the mechanism by which the
{m3-Ph2PCH2P(Ph)C6H4}(m-H)] (13e14), which are formed upon loss
of both phosphine and CO with concomitant oxidative addition of a
carbon-hydrogen bond.
The molecular structures of 13 and 14 are shown in Figs. 7 and 8,
respectively, with the captions containing selected bond lengths
and angles. The overall structures are very similar to that of 1 apart
from the replacement of an equatorial carbonyl group of 1 by a
phosphine ligand. As in 1, the osmiumeosmium edge that is
simultaneously bridged by the metalated phenyl group and the
ꢀ
ꢀ
ꢀ
hydride ligand [2.747(1) A in 1; 2.7732(7) A in 13 and 2.7729(7) A in
14] is significantly shorter than the other two [2.844(1) and
ꢀ
ꢀ
2.834(1) A in 1; 2.8415(7) and 2.8455(8) A in 13; 2.8492(6) and
2.8470(6) A in 14], a condition that reflects the constraining influ-
ꢀ
ence to the two bridging ligands. The most notable feature of 13 and
14 is the position of the phosphine ligand that is bound to the
osmium atom that is not coordinated by the diphosphine. Spec-
troscopic data are consistent with the solid-state structures. Each
31P{1H} NMR spectrum consists of two doublets and a singlet in
1:1:1 ratio, as expected for the three non-equivalent phosphorus
atoms in the cluster, and the hydride resonance in the 1H NMR
spectra appears as a doublet of doublet of doublets. Clusters 13 and
14 are CO substitution products of 1 that are not formed from the
direct reaction of 1 with these phosphines (Scheme 1). This un-
derscores the difference in reactivity between electronically satu-
rated and unsaturated carbonyl clusters; the former being
dominated by CO substitution.
Fig. 5. ORTEP diagram of the molecular structure of [Os3(CO)8(PFu3)2(m-dppm)] (12),
showing 50% probability thermal ellipsoids. Rinꢀg hydrogen atoms are omitted for
ꢀ
clarity. Selected bond distances (A) and angles( ): Os(1)dOs(2) 2.8732(5), Os(1)d
The mode of formation of these products (Scheme 4) is not fully
understood, however, given the very similar outcomes of the two
reactions we assume that they take place by the same mechanism.
For 10, we know from VT NMR studies (see preceding section)
that heating at 100 ꢀC promotes the formation of the 1,1-isomer
Os(3) 2.8960(5), Os(2)dOs(3) 2.8942(6), Os(1)dP(1) 2.304(2), Os(2)dP(2) 2.308(2),
Os(3)dP(3) 2.282(2), Os(3)dP(4) 2.281(2), Os(2)dOs(1)dOs(3) 60.220(14), Os(1)d
Os(2)dOs(3) 60.281(11), Os(2)dOs(3)dOs(1) 59.499(13), P(3)dOs(3)dOs(1)
154.15(6), P(3)dOs(3)dOs(2) 97.96(6), C(7)dOs(3)dP(3) 99.94(15), C(8)dOs(3)dP(3)
90.1(3), C(7)dOs(3)dP(4) 86.7(2), P(1)dC(11)dP(2) 116.9(5).

404
A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
Fig. 6. Geometry-optimized structures for the isomeric clusters 10a and 10b. The quoted free-energy (kcal/mol) difference is relative to 10a at room temperature.
10b (Scheme 3). While we cannot show this for 11, we assume that
isomerization also occurs but under the conditions required to
facilitate this, secondary processes leading to formation of 9 and 14
are competitive. Loss of a phosphine from the 1,1-isomers would
H)(
m
-dppm)] (15) (40%) and [Os3(CO)7(
-dppm)] (16) (31%) (Scheme 5). Cluster 8 results from phosphine
m-PFu2)(m3-h m-
2-C6H3CH3)(
H)(m
substitution by CO, while cluster 15 results from a loss of one PFu3
ligand, coupled with the activation of one carbon-phosphorus bond
in remaining the PFu3 ligand. This PeC bond cleavage generates the
result in the unsaturated intermediates, [Os3(CO)8(PR3)(m-dppm)],
which can add CO to give 7 and 9 or undergo CeH activation, fol-
lowed by CO loss, to give 13 and 14. Hall and Richmond [14] have
recently shown that addition of CO to the intermediate 46-electron
observed phosphido and capping furyne (m3-h
2-C4H2O) groups in the
product. The isolation of cluster 16 provides evidence for the acti-
vation of the toluene solvent during the thermolysis reaction. An
independent control experiment has confirmed that the furyne
cluster 15 does not serve as a precursor to 16.
ORTEP diagrams of the molecular structures of 15 and 16 are
depicted in Figs. 9 and 10, and selected bond distances and angles
are listed in the captions. Both are similar to the triruthenium
cluster [Os3(CO)9(
reasonable to suggest that the same is true for the putative species
[Os3(CO)8(PR3)( -dppm)]. The added CO must result from another
cluster molecule, which, in turn, has undergone CeH activation.
m-dppm)] (B) (Scheme 1) is rapid, and it seems
m
thiophyne and furyne clusters [Ru3(CO)7{
C4H2E)( -H)(
-dppm)] (E ¼ S, O) [17b]. A m3
2-C4H2O (in 15) and
m3
2-C6H3CH3 (in 16) ligand caps the open triangular array of
m-P(C4H3E)2}(m3- -
h2
2.6. Thermolysis of [Os3(CO)8(PFu3)2(
phosphorus bond cleavage
m-dppm)] (12): carbone
m
m
-h
-
h
osmium atoms. The hydride was not located directly but it is
Heating 12 in toluene for 2 h followed a different course to that of
10e11, leading instead to the formation of three products; [Os3
believed to span the dppm-bridged edge due to the significant
ꢀ
(CO)9(PFu3)(m-dppm)] (8) (19%), [Os3(CO)7(m-PFu2)(m3-h m-
2-C4H2O)(
lengthening of this bond [Os(2)dOs(3) 2.9668(4) A in 15; Os(1)d
ꢀ
Os(2) 2.9494(7) A in 16] as compared to the other [Os(1)dOs(2)
ꢀ
ꢀ
2.8508(4) A in 15; Os(2)dOs(3) 2.8527(6) A in 16]. In both, the
phosphido group bridges the open edge of the cluster in a slightly
unsymmetrical fashion [Os(1)dP(1) 2.396(2) and Os(3)dP(1)
ꢀ
ꢀ
2.373(2) A in 15; Os(3)dP(3) 2.393(2) and Os(1)dP(3) 2.364(2) A in
Fig. 7. ORTEP diagram of the molecular structure of [Os3(CO)7(PTh3){m3-Ph2PCH2P(Ph)
C6H4}( -H)] (13), showing 50% probability thermal ellipsoids. Ring hydrogen atoms are
Fig. 8. ORTEP diagram of the molecular structure of [Os3(CO)7(PPh3){m3-Ph2PCH2P(Ph)
m
C6H4}(
m
-H)] (14), showing 50% probability thermal ellipsoidꢀs. Ring hydrogen atoms are
ꢀ
ꢀ
ꢀ
omitted for clarity. Selected bond distances (A) and angles( ): Os(1)dOs(2) 2.8415(7),
Os(1)dOs(3) 2.7732(7), Os(2)dOs(3) 2.8455(8), Os(1)dP(1) 2.360(2), Os(2)dP(2)
2.336(2), Os(3)dP(3) 2.325(2), Os(1)dC(12) 2.362(8), Os(3)dC(12) 2.238(8), Os(3)d
Os(1)dOs(2) 60.886(16), Os(1)dOs(2)dOs(3) 58.372(11), Os(1)dOs(3)dOs(2)
60.742(19), P(1)dOs(1)dOs(3) 110.02(5), P(1)dOs(1)dOs(2) 166.33(5), P(2)dOs(2)d
Os(3) 77.98(5), P(2)dOs(2)dOs(1) 85.67(5), P(3)dOs(3)dOs(1) 131.33(5), P(3)d
Os(3)dOs(2) 89.25(5), Os(3)dC(12)dOs(1) 74.1(2), C(2)dOs(1)dOs(3) 116.6(3),
C(6)dOs(3)dOs(1) 121.3(3), P(2)dC(10)dP(3) 107.3(4).
omitted for clarity. Selected bond distances (A) and angles( ): Os(1)dOs(2) 2.8492(6),
Os(1)dOs(3) 2.8470(6), Os(2)dOs(3) 2.7729(7), Os(1)dP(1) 2.331(2), Os(2)dP(2)
2.324(2), Os(3)dP(3) 2.372(2), Os(2)dC(9) 2.245(9), Os(3)dC(9) 2.430(9), Os(3)d
Os(1)dOs(2) 58.260(16), Os(3)dOs(2)dOs(1) 60.830(14), Os(2)dOs(3)dOs(1)
60.910(15), P(3)dOs(3)dOs(1) 172.19(6), P(3)dOs(3)dOs(2) 111.99(6), P(1)dOs(1)d
Os(3) 84.54(6), P(1)dOs(1)dOs(2) 77.36(6), P(2)dOs(2)dOs(3) 131.01(6), P(2)d
Os(2)dOs(1) 90.03(6), Os(2)dC(9)dOs(3) 72.6(2), C(5)dOs(2)dOs(3) 117.7(3), C(7)d
Os(3)dOs(2) 114.9(3), P(1)dC(8)dP(2) 107.9(4).

A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
405
CO
Os
CO
R3P
OC
R3P
(CO)3
Os
(CO)
Ph2
P
3Ph2
Os
Os
P
P
CO
Os
R3P
CO
CO
Os
P
(CO)3 Ph2
Ph2
R3P
CO
1,2-isomer
1,1-isomer
Chart 1.
15) and 1411 (for 16) associated with the molecular ions. NMR
spectra of 15 show that in solution it exists in two isomeric forms.
Thus, the 31P{1H} NMR spectrum consists of two sets of resonances
in 4:1 ratio, each set consisting of two doublets and a doublet of
doublet due to the three phosphorus atoms. Consistent with this,
the aliphatic region of the 1H NMR spectrum exhibits four reso-
nances for the methylene protons of the dppm ligand at
2.73, and 2.53 with a relative intensity of 4:1:1:4, respectively,
while the hydride region displays two multiplets at
and ꢁ17.27 also in a 4:1 ratio. We have observed similar isomeri-
zation of furyne clusters previously [15i] and it most likely arises
from the different relative orientations of the oxygen atom in the
furyne ring (Chart 2). For 16, the spectroscopic data are in agree-
ment with the solid-state structure. The 1H NMR spectrum reveals
twenty-nine aromatic hydrogens as series of multiplets from
d 3.34, 3.10,
Fig. 9. ORTEP diagram of the molecular structure of [Os3(CO)7(m-PFu2)(m3- -
h2
C4H2O)(
m-H)(
m
-dppm)] (15), showing 50% probability thermal ellipsoids. Riꢀng
d
ꢁ17.31
ꢀ
hydrogen atoms are omitted for clarity. Selected bond distances (A) and angles( ):
Os(1)dOs(2) 2.8508(4), Os(2)dOs(3) 2.9668(4), Os(1)dP(1) 2.3956(17), Os(2)dP(2)
2.3534(17), Os(3)dP(3) 2.3750(16), Os(3)dP(1) 2.3734(16), Os(1)dC(8) 2.119(7),
Os(3)dC(9) 2.125(6), Os(2)dC(8) 2.427(6), Os(2)dC(9) 2.282(6), Os(1)dOs(2)dOs(3)
84.723(10), P(1)dOs(3)dP(3) 169.29(6), P(1)dOs(3)dOs(2) 76.45(4), P(1)dOs(1)d
Os(2) 78.47(4), Os(3)dP(1)dOs(1) 110.60(6), Os(3)dC(9)dOs(2) 84.5(2), Os(1)d
C(8)dOs(2) 77.3(2), C(9)dOs(2)dC(8) 34.2(2), C(6)dOs(3)dOs(2) 140.03(19), C(4)d
Os(2)dOs(3) 114.7(2), P(2)dC(20)dP(3) 113.6(3).
d
6.32e7.62, with the lone methyl group appearing as a singlet at
d
1.57. The diastereotopic methylene hydrogens and the bridging
16]. Each capping ligand is bound to the cluster through a h2
interaction, being slightly tilted toward the -coordination side as
observed in the related thiophyne clusters [Os3(CO)9(m3
k1 h2
PTh2(C4H2S)( -H)] [17g], [Os3(CO)9(m3 -H)]
k1 2-PPh2(C4H2S)(
[17d] and [Os3(CO)8(PPh2Th){m3 -H)] [17d].
k1 2-PTh2(C4H2S)}(
,p-
hydride appear as separate resonances centered at
d 3.26, 2.50,
and ꢁ17.22, respectively. The 31P NMR and ESI mass spectral data
p
are summarized in the experimental section.
-
:
-
m
-
:h
m
3. Summary and conclusions
-
:h
m
Spectroscopic data support the observed solid-state structures,
for example ESI mass spectra show [MþeH] peaks at m/z 1383 (for
In this work we set out to investigate the comparative reactivity
of PTh3, PFu3 and PPh3 towards the lightly stabilized triosmium
cluster [Os3(CO)8{m3-Ph2PCH2P(Ph)C6H4}(m-H)] (1). As detailed in
Scheme 2, even at room temperature the reaction is complex and
leads to a number of different product types. The three phosphines
broadly behave in a similar manner, although it is notable that
PTh3 and PFu3 favor formation of the bis(phosphine) adducts
[Os3(CO)8(PR3)2(m-dppm)] 10 (54%) and 12 (66%) respectively,
while with PPh3 products 6 and 9 (29 and 19%) containing a single
phosphine ligand are more abundant. The key intermediates in
determining this product ratio are likely the saturated mono-
phosphine complexes [Os3(CO)8(PR3){m3-Ph2PCH2P(Ph)C6H4}(
H)] (4e6). For both PFu3 and PTh3 the major products are the
bis(phosphine) complexes [Os3(CO)8(PR3)2( -dppm)] (10 and 12),
m-
m
further phosphine addition being favored with respect to PPh3 by
both their smaller cone angles (PFu3 133ꢀ vs PPh3 148ꢀ) and the
stronger p-acceptor nature, which reduces electron-density at the
cluster center. Both 1,1- and 1,2-isomers were found, and in order to
probe their relative stabilities a series of DFT calculations were
carried out, and the computed free energies (at room temperature)
of the different isomers are in agreement with the experimentally
observed diffraction structures. The bis(phosphine) complexes
were not stable at higher temperatures and converted into a
number of new species, all of which resulted from phosphine loss.
Interestingly, while PPh3 and PTh3 complexes 10e11 behaved in a
similar manner, thermal rearrangement cleavage of the PFu3
adduct 12 was dominated by carbonephosphorus bond cleavage of
the PFu3 ligand (71% total yield). This resulted in formation of a new
furyne cluster 15 together with a related toluene-derived complex
16, formally resulting from exchange of the furyne by the reaction
solvent.
Fig. 10. ORTEP diagram of the molecular structure of one of the unique molecules of
[Os3(CO)7(
thermal ellipsoids. Ring hydrogen atoms are omitted for clarity. Selected bond dis-
m-PFu2)(m3-h m-H)(m-dppm)] (16), showing 50% probability
2-C6H3CH3)(
ꢀ
ꢀ
tances (A) and angles( ): Os(1)dOs(2) 2.9494(7), Os(2)dOs(3) 2.8527(6), Os(1)dP(1)
2.391(2), Os(2)dP(2) 2.366(2), Os(3)dP(3) 2.393(2), Os(1)dP(3) 2.364(2), Os(1)dC(9)
2.169(10), Os(2)dC(10) 2.329(9), Os(2)dC(9) 2.243(9), Os(3)dC(10) 2.093(9), Os(3)d
Os(2)dOs(1) 83.803(14), P(3)dOs(1)dP(1) 167.87(8), P(3)dOs(1)dOs(2) 80.03(6),
P(3)dOs(3)dOs(2) 81.61(5), Os(1)dP(3)dOs(3) 109.15(9), Os(1)dC(9)dOs(2) 83.9(3),
Os(3)dC(10)dOs(2) 80.2(3), C(9)dOs(2)dC(10) 37.0(3), C(1)dOs(1)dOs(2) 130.6(3),
C(4)dOs(2)dOs(1) 110.2(3), P(1)dC(8)dP(2) 114.8(4).

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A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
CO
Os
Th3P
OC
CO
Os
(CO)3
Os
Ph2
P
Th3P
Th3P
100 oC
(CO)
Os
3Ph2
P
CO
Os
CO
Th3P
P
CO
Os
P
Ph2
(CO)3 Ph2
CO
10a
10b
Scheme 3.
This work demonstrates that the relatively simple procedure of
NMR (CDCl3, 25 ꢀC):
d
¼ 8.54 (m, 2H), 8.24 (m, 2H), 7.67 (m, 15H),
adding two equivalents of a phosphine to 1 is considerably more
complicated than expected, and further that there are some sig-
nificant differences not only between PPh3 and PFu3/PTh3 but also
between PFu3 and PTh3. This mirrors many aspects of our previous
work with these phosphines [15cef,17geh] and suggests that the
chemistries of these ligands are significantly different warranting
further study.
7.09 (m, 2H), 6.96 (m, 2H), 6.79 (m, 1H), 6.43 (m, 2H), 6.14 (m, 1H),
5.90 (m, 1H), 5.24 (m, 1H), 3.82 (m, 1H), ꢁ18.09 (m, 1H). 31P{1H}
NMR (CDCl3, 25 ꢀC):
d
¼ ꢁ40.2 (d, JPP ¼ 8.4 Hz, 1P), ꢁ33.6 (s,
1P), ꢁ22.9 (dd, JPP ¼ 63.6, 8.4 Hz, 1P), ꢁ28.8 (d, JPP ¼ 63.6 Hz, 1P).
Characterizing data for 7: Anal. Calcd for C46H31O9Os3P3S3: C, 37.14;
H, 2.10. Found: C, 37.39; H, 2.16. IR (CH2Cl2): nCO ¼ 2064 w, 2000 s,
1980 vs, 1959 sh, 1936 m cmꢁ1. 1H NMR (CDCl3, 25 ꢀC):
d
¼ 7.55 (m,
3H), 7.46 (m, 3H), 7.33 (m, 20H), 7.16 (m, 3H), 4.96 (t, J ¼ 10.6 Hz,
1H). 31P{1H} NMR (CDCl3, 25 ꢀC):
d
¼ ꢁ24.6 (d, JPP ¼ 53.6 Hz,
4. Experimental
1P), ꢁ27.6 (d, JPP ¼ 53.6 Hz, 1P), ꢁ43.4 (s, 1P). Characterizing data
for 10: Anal. Calcd for C57H40O8Os3P4S6: C, 39.35; H, 2.32. Found: C,
39.61; H, 2.39. IR (CH2Cl2): nCO ¼ 2048 w, 1994 s, 1970 vs, 1931
4.1. General
m cmꢁ1. 1H NMR (CDCl3, 25 ꢀC): aliphatic region: 10a:
d
¼ 4.68 (t,
[Os3(CO)12] was purchased from Strem Chemicals Inc. and used
without further purification and [Os3(CO)8{m3-Ph2PCH2P(Ph)
C6H4}(m-H)] (1) was prepared according to the published procedure
J ¼ 10.4 Hz); 10b: ¼ 4.88 (t, J ¼ 10.8 Hz), aromatic region: 10aeb:
d
d
¼ 7.49e6.88 (m). 31P{1H} NMR (CDCl3, 25 ꢀC): 10a:
¼ ꢁ20.7 (dd,
d
JPP
¼ 50.2, 9.2 Hz), ꢁ27.3 (d, JPP ¼ 50.2 Hz), ꢁ39.3 (d,
[11]. Triphenylphosphine, tri(2-thienyl)phosphine and tri(2-furyl)
phosphine were purchased from E. Merck, Acros Organics and
Aldrich, respectively, and used as received. All reactions were car-
ried out under a nitrogen atmosphere using standard Schlenk
techniques. Reagent-grade solvents were dried by standard
methods prior to use. Infrared spectra were recorded on a Shi-
madzu FTIR 8101 spectrophotometer. NMR spectra were recorded
on Bruker DPX 400 instruments. Elemental analyses were per-
formed by Microanalytical Laboratories, University College London.
JPP ¼ 9.2 Hz), ꢁ51.8 (s); 10b:
d
¼ ꢁ29.1 (s), ꢁ40.8 (s).
4.3. Reaction of [Os3(CO)8{m3-Ph2PCH2P(Ph)C6H4}(m-H)] (1) with
PFu3
To a CH2Cl2 solution (20 mL) of 1 (50 mg, 0.042 mmol) was
added PFu3 (20 mg, 0.086 mmol) and the mixture was then stirred
at 25 ꢀC for 5 h. The solvent was removed under reduced pressure
and the residue chromatographed by TLC on silica gel. Elution with
hexane/CH2Cl2 (3:2, v/v) gave four bands which afforded the
4.2. Reaction of [Os3(CO)8{m3-Ph2PCH2P(Ph)C6H4}(m-H)] (1) with
PTh3
following compounds in order of elution: [Os3(CO)10
(3 mg, 6%) as yellow crystals, [Os3(CO)8(PFu3){m3-Ph2PCH2P(Ph)
C6H4}( -H)] (5) (7 mg, 12%) as yellow crystals, [Os3(CO)9(PFu3)(
dppm)] (8) (5 mg, 8%) as yellow crystals from hexane/CH2Cl2 at 4 ꢀC
(m-dppm)] (2)
To a CH2Cl2 solution (20 mL) of 1 (50 mg, 0.042 mmol) was
added PTh3 (24 mg, 0.086 mmol) and the mixture was then stirred
at 25 ꢀC for 8 h. The solvent was removed by rotary evaporation and
the residue chromatographed by TLC on silica gel. Elution with
hexane/CH2Cl2 (7:3, v/v) gave four bands which afforded the
following compounds in order of elution: [Os3(CO)10
(3 mg, 6%) as yellow crystals, [Os3(CO)8(PTh3){m3-Ph2PCH2P(Ph)
C6H4}(
m
m-
and [Os3(CO)8(PFu3)2(m-dppm)] (12) (46 mg, 66%) as orange crys-
tals from hexane/C2H4Cl2 at 4 ꢀC. Characterizing data for 5: Anal.
Calcd for C45H31O11Os3P3: C, 38.29; H, 2.22. Found: C, 38.52; H, 2.26.
(
m
-dppm)] (2)
IR (CH2Cl2): nCO ¼ 2027 m, 2003 vs, 1991 s, 1956 m, 1935 m,br cmꢁ1
.
1H NMR (CDCl3, 25 ꢀC):
d
¼ 8.14 (m, 1H), 7.19 (m, 18H), 6.89 (m, 1H),
m
-H)] (4) (8 mg, 13%) as yellow crystals, [Os3(CO)9(PTh3)(
m-
-
6.69 (m, 2H), 6.65 (m, 2H), 6.40 (m, 1H), 6.35 (m, 1H), 6.06 (m, 1H),
dppm)] (7) (7 mg, 11%) as yellow crystals and [Os3(CO)8(PTh3)2(
m
5.90 (m, 1H), 5.33 (m, 1H), 3.61 (m, 1H), ꢁ18.36 (m, 1H). 31P{1H}
dppm)] (10) (40 mg, 54%) as orange crystals after recrystallization
from hexane/CH2Cl2 at 4 ꢀC. Characterizing data for 4: Anal. Calcd
for C45H31O8Os3P3S3: C, 37.03; H, 2.14. Found: C, 37.29; H, 2.19. IR
(CH2Cl2): nCO ¼ 2025 m, 2001 vs,1987 s,1949 m,1932 m, br cmꢁ1. 1H
NMR (CDCl3, 25 ꢀC):
d
¼ ꢁ53.3 (s, 1P), ꢁ22.7 (d, JPP ¼ 67.2 Hz,
1P), ꢁ14.0 (d, JPP ¼ 67.2 Hz, 1P). Characterizing data for 8: Anal.
Calcd for C46H31O12Os3P3: C, 38.38; H, 2.17. Found: C, 38.63; H, 2.23.
IR (CH2Cl2): nCO ¼ 2065 w, 2029 w, 2001 s, 1983 vs, 1967 sh, 1937
Ph
P
2 P
Ph
R3P
110 oC
7, R = Th (58%)
10, R = Th
(CO)
Os
Os
3
+
(OC)2
9, R = Ph (52%)
11, R = Ph
13, R = Th (28%)
14, R = Ph (36%)
H
Os
(CO)2
Scheme 4.

A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
407
O
CH3
Fu2P
(OC)3Os
Fu2P
Os
(CO)2
Os
110 oC
Ph2
P
(CO)2
Os
Ph2
P
12
+
8
(OC)3
+
19%
Os
(CO)2
P
Os
(CO)2
P
Ph2
H
Ph2
H
40%
15
16
31%
Scheme 5.
m cmꢁ1. 1H NMR (CDCl3, 25 ꢀC):
d
¼ 7.97 (m, 2H), 7.69 (m, 2H), 7.65
as green crystals after recrystallization from hexane/CH2Cl2 at 4 ꢀC.
The third band gave a minor unidentified product. Characterizing
data for 13: Anal. Calcd for C44H31O7Os3P3S3: C, 36.91; H, 2.19.
Found: C, 37.18; H, 2.24. IR (CH2Cl2): nCO ¼ 2031 vs, 1990 vs, 1977 s,
(m, 2H), 7.51 (m, 2H), 7.34 (m, 15H), 6.88 (m, 2H), 6.69 (m, 2H), 6.45
(m, 2H), 4.33 (m, 1H), 4.20 (m, 1H). 31P{1H} NMR (CDCl3, 25 ꢀC):
d
¼ ꢁ56.8 (s, 1P), ꢁ27.4 (d, JPP ¼ 53.4 Hz, 1P), ꢁ24.8 (d, JPP ¼ 53.4 Hz,
1P). Characterizing data for 12: Anal. Calcd for C57H40O14Os3P4: C,
41.65; H, 2.46. Found: C, 41.86; H, 2.53. IR (CH2Cl2): nCO ¼ 1993 s,
1956 m, 1918 s cmꢁ1. 1H NMR (CDCl3, 25 ꢀC):
d
¼ 8.12 (m, 1H), 7.89
(m, 2H), 7.60 (m, 15H), 7.11 (m, 3H), 6.98 (m, 3H), 6.56 (m, 1H), 6.23
1967 vs, 1927 m cmꢁ1. 1H NMR (CDCl3, 25 ꢀC):
d
¼ 7.43 (m, 6H), 7.31
(m, 2H), 6.15 (m, 1H), 4.78 (m, 1H), 3.77 (m, 1H), ꢁ12.16 (ddd,
(m, 20H), 6.47 (m, 6H), 6.28 (m, 6H), 4.87 (t, J ¼ 10.4 Hz, 2H). 31P{1H}
J ¼ 10.4, 9.2, 1.8 Hz, 1H). 31P{1H} NMR (CDCl3, 25 ꢀC):
d
¼ ꢁ15.1 (d,
NMR (CDCl3, 25 ꢀC):
d
¼ ꢁ28.3 (s, 2P), ꢁ50.6 (s, 2P).
JPP ¼ 71.8 Hz, 1P), ꢁ19.8 (d, JPP ¼ 71.8 Hz, 1P), ꢁ25.7 (s, 1P).
4.6. Thermolysis of [Os3(CO)8(PPh3)2(m-dppm)] (11)
4.4. Reaction of [Os3(CO)8{m3-Ph2PCH2P(Ph)C6H4}(m-H)] (1) with
PPh3
A toluene solution (15 mL) of 11 (40 mg, 0.023 mmol) was
heated to reflux for 30 min. The solvent was removed by rotary
evaporation and the residue chromatographed by TLC on silica gel.
Elution with hexane/CH2Cl2 (7:3, v/v) developed three bands. The
PPh3 (20 mg, 0.086 mmol) was added to a CH2Cl2 solution (20 mL)
of 1 (50 mg, 0.042 mmol) and the mixture was then stirred at 25 ꢀC
for 7 h. The solvent was removed under reduced pressure and the
residue subjected toTLC on silica gel forchromatographic separation.
Elutionwith hexane/CH2Cl2 (7:3, v/v) gave four bands which afforded
the following compounds in order of elution: [Os3(CO)10
(2) (6 mg, 11%) as yellow crystals, [Os3(CO)9(PPh3)( -dppm)] (9)
(12 mg, 19%) as yellow crystals, [Os3(CO)8(PPh3)2( -dppm)] (11)
(17 mg, 24%) as orange crystals and [Os3(CO)8(PPh3){m3-Ph2
first and second bands gave [Os3(CO)9(PPh3)(m-dppm)] (9) (18 mg,
52%) as yellow crystals and [Os3(CO)7(PPh3){m3-Ph2PCH2P(Ph)
C6H4}(m-H)] (14) (12 mg, 36%) as green crystals after recrystalliza-
(m-dppm)]
tion from hexane/CH2Cl2 at 4 ꢀC. The third band gave a minor un-
m
m
identified product. Characterizing data for 14: Anal. Calcd for
C
50H37O7Os3P3: C, 42.48; H, 2.64. Found: C, 42.83; H, 2.72. IR
(CH2Cl2): nCO ¼ 2103 m, 2061 m, 2044 vs, 2012 s, 1964 w, 1940 w
cmꢁ1. 1H NMR (CDCl3, 25 ꢀC):
PCH2P(Ph)C6H4}(m-H)] (6) (18 mg, 29%) as yellow crystals after
d
¼ 7.95 (m, 2H), 7.81 (m, 2H), 7.62 (m,
recrystallization from hexane/CH2Cl2 at 4 ꢀC. Characterizing data for
9: Anal. Calcd for C52H37O9Os3P3: C, 42.50; H, 2.54. Found: C, 42.82; H,
2.61. IR (CH2Cl2): nCO ¼ 2060 m, 2028 w,1997 s,1976 vs,1964 sh,1933
6H), 7.43 (m, 3H), 7.35 (m, 10H), 7.13 (m, 7H), 6.98 (m, 1H), 6.90 (m,
2H), 6.64 (m, 1H), 4.75 (m, 1H), 3.68 (m, 1H), ꢁ12.15 (ddd, J ¼ 18.4,
10.8, 7.6 Hz, 1H). 31P{1H} NMR (CDCl3, 25 ꢀC):
(d, JPP ¼ 74.5 Hz, 1P), e20.5 (d, JPP ¼ 74.5 Hz, 1P).
d
¼ 14.2 (s, 1P), e14.7
m cmꢁ1. 1H NMR (CDCl3, 25 ꢀC):
d
¼ 7.50 (m, 6H), 7.35 (m, 29H), 4.93
(t, J ¼ 10.4 Hz, 2H). 31P{1H} NMR (CDCl3, 25 ꢀC):
¼ 0.8 (s, 1P), ꢁ24.6
d
(d, JPP ¼ 52.2 Hz, 1P), ꢁ27.7 (d, JPP ¼ 52.2 Hz, 1P).
4.7. Thermolysis of [Os3(CO)8(PFu3)2( -dppm)] (12)
m
4.5. Thermolysis of [Os3(CO)8(PTh3)2(m-dppm)] (10)
A toluene solution (15 mL) of 12 (30 mg, 0.018 mmol) was
heated at 110 ꢀC for 2 h. The solvent was removed by rotary
evaporation and the residue separated by TLC on silica gel. Elution
with hexane/CH2Cl2 (1:1, v/v) developed six bands. The second,
A toluene solution (15 mL) of 10 (30 mg, 0.017 mmol) was heated
to reflux for 3 h. The solvent was removed under reduced pressure
and the residue separated by TLC on silica gel. Elution with hexane/
CH2Cl2 (7:3, v/v) developed three bands. The first and second bands
third and fifth bands gave [Os3(CO)7(
dppm)] (15) (10 mg, 40%) as colorless crystals, [Os3(CO)9(PFu3)(
dppm)] (8) (5 mg, 19%) as yellow crystals and [Os3(CO)7(
2-C6H3CH3)(
-H)(
m
-PFu2)(m3
-
h
2-C4H2O)(
m-H)(
m
m
-
-
-
gave [Os3(CO)9(PTh3)(m-dppm)] (7) (15 mg, 58%) as yellow crystals
m-PFu2)(m3
and [Os3(CO)7(PTh3){m3-Ph2PCH2P(Ph)C6H4}(m-H)] (13) (7 mg, 28%)
h
m
m-dppm)] (16) (8 mg, 31%) as colorless crystals
after recrystallization from hexane/CH2Cl2 at 4 ꢀC. The other three
bands gave minor unidentified products. Characterizing data for 15:
Anal. Calcd for C44H31O10Os3P3: C, 38.20; H, 2.26. Found: C, 38.43;
H, 2.33. IR (CH2Cl2): nCO ¼ 2055 s, 2031 s, 1998 s, 1980 s, 1957
O
O
Fu2P
sh cmꢁ1. 1H NMR (CDCl3, 25 ꢀC): aliphatic region: 15a:
d
¼ 3.34 (q,
¼ 3.10 (q, J ¼ 24.0,
11.8 Hz), 2.73 (q, J ¼ 24.0, 11.8 Hz), aromatic region: 15aeb:
¼ 7.83e6.36 (m), hydride region: 15a: e17.31 (m); 15b: e17.27
(m). 31P{1H} NMR (CDCl3, 25 ꢀC): 15a:
¼ 13.6 (dd, JPP ¼ 105.2,
203.2 Hz), 8.0 (d, JPP ¼ 105.2 Hz), e92.6 (d, JPP ¼ 203.2 Hz); 15b:
Fu2P
(CO)2
Ph2
(CO)2
Os
Ph2
P
J ¼ 24.6,12.4 Hz), 2.53 (q, J ¼ 24.6,12.4 Hz); 15b:
d
(OC)3 Os
Os
P
(OC)3 Os
Os
(CO)2
P
d
Os
(CO)2
P
Ph2
Ph2
H
d
H
d
¼ 10.2 (dd, J ¼ 213.2, 98.8 Hz), 4.4 (d, J ¼ 98.8 Hz), ꢁ91.4 (d,
15b
15a
JPP ¼ 213.2 Hz). ESI-MS: m/z ¼ 1383 [MþeH]. Characterizing data
Chart 2.
for 16: Anal. Calcd for C47H35O9Os3P3: C, 40.11; H, 2.51. Found: C,

408
A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
Table 1
Crystal data and structure refinement for the complexes [Os3(CO)8(PFu3){m3-Ph2PCH2P(Ph)C6H4}(
[Os3(CO)8(PTh3)2( -dppm)] (10), [Os3(CO)8(PFu3)2( -dppm)] (12) and [Os3(CO)7(PTh3){m3-Ph2PCH2P(Ph)C6H4}(
[Os3(CO)7(
-PFu2)(m3
m
-H)] (5), [Os3(CO)9(PTh3)(
-H)] (13). [Os3(CO)7(PPh3){m3-Ph2PCH2P(Ph)C6H4}(
2-C6H3CH3)(
m-PFu2)(m3-h m-H)(m-dppm)] (16).
m
-dppm)] (7) and [Os3(CO)9(PPh3)(
m
-dppm)] (9).
m
m
m
m
-H)] (14),
m
-h
2-C4H2O)(
m
-H)(m
-dppm)] (15) and [Os3(CO)7(
5.CH2Cl2
7
9.0.5 CH2Cl2
Chemical formula
Formula mass
Crystal system
Space group
C46H33Cl2O11Os3P3
1496.13
Monoclinic
P21/n
15.616(4)
20.069(5)
15.846(4)
90
102.479(4)
90
C46H31O9Os3P3S3
1487.40
Monoclinic
C2/c
40.680(5)
11.386(1)
19.890(2)
90
92.453(2)
90
C52.50H37.50ClO9Os3P3
1511.28
Monoclinic
C2/c
41.535(6)
11.645(2)
20.206(3)
90
92.990(2)
90
ꢀ
a [A]
ꢀ
b [A]
ꢀ
c [A]
aꢀ
bꢀ
gꢀ
3
ꢀ
Cell volume [A ]
4848(2)
9205(2)
9760(2)
Z
4
8
8
Calcd. density [g cmꢁ3
]
2.050
8.109
2.147
8.558
2.057
8.002
Abs. coeff.
m
[mmꢁ1
]
F(000)
2816
5600
5716
Crystal color
Crystal size [mm]
range for data collection [ꢀ]
Yellow
Orange
Orange
0.30 ꢂ 0.30 ꢂ 0.06
2.62 to 28.29
ꢁ19 ꢃ h ꢄ 20,
ꢁ25 ꢃ h ꢄ 25,
ꢁ20 ꢃ h ꢄ 20
99.6% to 26.00ꢀ
40,924
0.24 ꢂ 0.24 ꢂ 0.04
2.75 to 28.30
ꢁ54 ꢃ h ꢄ 53,
ꢁ15 ꢃ h ꢄ 15,
ꢁ26 ꢃ h ꢄ 26
99.7% to 26.00ꢀ
39,109
0.18 ꢂ 0.17 ꢂ 0.05
2.29 to 28.31
ꢁ55 ꢃ h ꢄ 53,
ꢁ15 ꢃ h ꢄ 15,
ꢁ26 ꢃ h ꢄ 26
99.5% to 26.00ꢀ
40,686
q
Index ranges
Completeness to
q
Reflections collected
Independent reflections
Min. and max. transmission
Data/restraints/parameters
11,430 (Rint ¼ 0.0892)
0.1947 and 0.6418
11,430/0/596
R1 ¼ 0.0484,
10,997 (Rint ¼ 0.0521)
0.2332 and 0.7259
10,997/0/575
R1 ¼ 0.0297,
wR2 ¼ 0.0658
R1 ¼ 0.0367,
wR2 ¼ 0.0683
1.029
11,702 (Rint ¼ 0.0461)
0.3268 and 0.6904
11,702/0/621
R1 ¼ 0.0308,
wR2 ¼ 0.0731
R1 ¼ 0.0378,
wR2 ¼ 0.0757
1.033
Final R indices [F2 > 2
s]
wR2 ¼ 0.1246
R1 ¼ 0.0621,
R indices (all data)
wR2 ¼ 0.1320
1.045
4.254 andꢁ2.117
Goodness-of-fit on F2
Largest diff. peak and hole [e.A
ꢀꢁ3
]
1.404 andꢁ1.431
1.803 andꢁ1.942
10.1.5 CH2Cl2
12.CH2Cl2.4H2O
13.CHCl3
Chemical formula
Formula mass
Crystal system
Space group
C58.5H43Cl3O8Os3P4S6
1867.12
Monoclinic
P21/n
23.143(4)
21.980(3)
24.468(4)
90
98.651(2)
90
C59H52Cl2O18Os3P4
1814.39
Triclinic
P 1 bar
12.099(2)
15.578(2)
19.092(3)
76.243(2)
72.173(2)
C45H32Cl3O7Os3P3S3
1550.75
Monoclinic
P21/c
13.424(4)
19.906(5)
18.093(5)
90
90.885(4)
90
ꢀ
a [A]
ꢀ
b [A]
ꢀ
c [A]
aꢀ
bꢀ
gꢀ
86.758(2)
3327.0(8)
3
ꢀ
Cell volume [A ]
12,305(3)
4834(2)
Z
8
2
4
Calcd. density [g cmꢁ3
]
2.016
6.672
1.811
5.957
2.131
8.309
Abs. coeff.
m
[mmꢁ1
]
F(000)
7144
1744
2920
Crystal color
Crystal size [mm]
range for data collection [ꢀ]
Orange
Orange
Red
0.46 ꢂ 0.16 ꢂ 0.13
1.13 to 28.31
ꢁ30 ꢃ h ꢄ 30,
ꢁ29 ꢃ h ꢄ 29,
ꢁ32 ꢃ h ꢄ 31
99.8% to 26.00ꢀ
1,04,259
0.42 ꢂ 0.12 ꢂ 0.04
2.38 to 28.26
ꢁ16 ꢃ h ꢄ 16,
ꢁ20 ꢃ h ꢄ 20,
ꢁ24 ꢃ h ꢄ 24
97.6% to 26.00ꢀ
28,233
0.46 ꢂ 0.42 ꢂ 0.12
2.47 to 28.33
ꢁ17 ꢃ h ꢄ 17,
ꢁ26 ꢃ h ꢄ 26,
ꢁ23 ꢃ h ꢄ 24
99.8% to 26.00ꢀ
39,578
q
Index ranges
Completeness to
q
Reflections collected
Independent reflections
Min. and max. transmission
Data/restraints/parameters
29,564 (Rint ¼ 0.0498)
0.1493 and 0.4775
29,564/0/1466
R1 ¼ 0.0439,
wR2 ¼ 0.1082
R1 ¼ 0.0541,
wR2 ¼ 0.1141
1.037
15,110 (Rint ¼ 0.0458)
0.1887 and 0.7966
15,110/2/775
R1 ¼ 0.0635,
wR2 ¼ 0.1971
R1 ¼ 0.0731,
wR2 ¼ 0.2172
0.977
11,407 (Rint ¼ 0.0740)
0.1146 and 0.4355
11,407/0/568
R1 ¼ 0.0508,
wR2 ¼ 0.1271
R1 ¼ 0.0613,
wR2 ¼ 0.1333
1.041
Final R indices [F2 > 2
s]
R indices (all data)
Goodness-of-fit on F2
Largest diff. peak and hole [e.A
ꢀꢁ3
]
3.094 andꢁ1.768
4.738 andꢁ3.600
4.184 andꢁ1.884
14.1.5CH2Cl2
15
16.2CH2Cl2
Chemical formula
Formula mass
Crystal system
Space group
C52H41Cl3O7Os3P3
1547.71
Triclinic
C46H31O9Os3P3
1391.22
Triclinic
C98H78Cl8O16Os6P6
3154.23
Triclinic
P 1 bar
P 1 bar
P 1 bar

A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
409
Table 1 (continued )
14.1.5CH2Cl2
15
16.2CH2Cl2
ꢀ
a [A]
10.487(2)
15.456(3)
16.719(3)
90.899(3)
99.824(3)
107.982(3)
2533.0(8)
10.0797(6)
11.7563(7)
19.667(1)
79.920(1)
76.121(1)
12.085(2)
12.219(2)
38.384(6)
94.299(3)
92.388(3)
119.605(2)
4894(1)
ꢀ
b [A]
ꢀ
c [A]
aꢀ
bꢀ
gꢀ
67.817(1)
2085.8(2)
3
ꢀ
Cell volume [A ]
Z
2
2
2
Calcd. density [g cmꢁ3
]
2.029
7.810
2.215
9.289
2.140
8.143
Abs. coeff.
m
[mmꢁ1
]
F(000)
1466
1304
2984
Crystal color
Crystal size [mm]
range for data collection [ꢀ]
Green
Yellow
Yellow
0.12 ꢂ 0.12 ꢂ 0.03
2.58 to 28.32
ꢁ13 ꢃ h ꢄ 13,
ꢁ20 ꢃ h ꢄ 19,
ꢁ22 ꢃ h ꢄ 22
97.3% to 26.00ꢀ
21,849
0.16 ꢂ 0.08 ꢂ 0.06
2.07 to 28.28
ꢁ13 ꢃ h ꢄ 12,
ꢁ15 ꢃ h ꢄ 15,
ꢁ24 ꢃ h ꢄ 25
97.2% to 26.00ꢀ
17,296
0.24 ꢂ 0.17 ꢂ 0.08
1.07 to 28.28
ꢁ16 ꢃ h ꢄ 15,
ꢁ16 ꢃ h ꢄ 16,
ꢁ50 ꢃ h ꢄ 50
97.2% to 26.00ꢀ
41,880
q
Index ranges
Completeness to
q
Reflections collected
Independent reflections
Min. and max. transmission
Data/restraints/parameters
11,542 (Rint ¼ 0.0453)
0.4542 and 0.7995
11,542/0/603
R1 ¼ 0.0460,
wR2 ¼ 0.1011
R1 ¼ 0.0740,
wR2 ¼ 0.1233
1.032
9207 (Rint ¼ 0.0362)
0.3180 and 0.6057
9207/0/541
R1 ¼ 0.0362,
wR2 ¼ 0.0718
R1 ¼ 0.0527,
wR2 ¼ 0.0780
0.986
22,249 (Rint ¼ 0.0344)
0.2454 and 0.5620
22,249/0/1204
R1 ¼ 0.0466,
Final R indices [F2 > 2
s]
wR2 ¼ 0.1378
R1 ¼ 0.0585,
R indices (all data)
wR2 ¼ 0.1545
1.037
2.405 andꢁ2.246
Goodness-of-fit on F2
Largest diff. peak and hole [e.A
ꢀꢁ3
]
2.035 andꢁ1.689
2.667 andꢁ2.297
40.33; H, 2.56. IR (CH2Cl2): nCO ¼ 2061 s, 2032 s, 2008 s, 1987 s, 1971
s cmꢁ1. 1H NMR (CDCl3, 25 ꢀC):
oxygen atom has a short contact with a sulfur atom on a neigh-
boring molecule [O(2)-S(10) 3.204 A]. Four carbon atoms in thienyl
ꢀ
d
¼ 7.62 (m, 3H), 7.51 (m, 1H), 7.45
(m, 3H), 7.23e7.03 (m,13H), 6.97 (m, 2H), 6.83 (m, 2H), 6.74 (m,1H),
6.59 (m, 1H), 6.41 (m, 1H), 6.39 (m, 1H), 6.32 (m, 1H), 3.26 (dd,
J ¼ 24.6, 12.4 Hz, 1H), 2.50 (dd, J ¼ 24.6, 12.4 Hz, 1H), 1.57 (s, 3H,
rings, namely C(27), C(47), C(59) and C(63), were refined only iso-
tropically. The asymmetric unit of 12 contains a disordered mole-
cule of dichloromethane and four extra unconnected peaks in the
difference map which have been modeled as oxygen atoms (pre-
sumably from water). Hydrogen atoms were not placed on any of
these solvent molecules. The asymmetric unit of 13 contains a
disordered molecule of chloroform. Cluster 14 co-crystallized with
one and a half molecules of dichloromethane, the half molecule
being disordered over two sites. Both were refined only isotropi-
cally and protons were not included for the disordered molecule.
For 16 there were two clusters and four molecules of dichloro-
methane in the asymmetric unit. In one of the solvent molecules a
chlorine atom was equally disordered over two sites [Cl(8) and
Cl(9)]. These atoms were refined only isotropically and protons
were not generated. Scattering factors were taken from Interna-
tional Tables for X-ray Crystallography [27]. Crystallographic data
are given in Table 1.
31
Me), ꢁ17.22 (dt, J ¼ 10.8, 7.6 Hz, 1H). P{1H} NMR (CDCl3, 25 ꢀC):
d
¼ 19.2 (dd, JPP ¼ 111.6, 210.9 Hz, 1P), 5.8 (d, JPP ¼ 111.6 Hz,
1P), ꢁ98.0 (d, JPP ¼ 210.9 Hz, 1P). ESI-MS: m/z ¼ 1411 [MþeH].
4.8. X-ray crystallography
Single crystals of 5, 7, 9, 10, 13, 14, 15 and 16 suitable for X-ray
structure analysis were grown by slow diffusion of hexane into
dichloromethane solution at 4 ꢀC and that of 12 by slow diffusion of
hexane into dichloroethane solution at 4 ꢀC. Diffraction intensities
were collected at 150(2) K with a Bruker SMART APEX2 CCD
ꢀ
diffractometer using Mo-K
a
radiation (
l
¼ 0.71073 A). Indexing and
initial cell refinements as well as the data collection were all done
using APEX2 [22] software. Data integration was accomplished
with SAINT [23] software and numerical absorption correction
(based on the real shape of the crystals) followed by scaling pro-
cedure with SADABS program [24] were used to account for sys-
tematic effects. The structures were solved by direct methods [25]
and refined by full-matrix least squares [26]. In most of the struc-
tures all non-hydrogen atoms were refined anisotropically and
hydrogen atoms were included using a riding model. The structure
of 5 contains a dichloromethane molecule in which one of the
chlorine atoms is disordered [Cl(2A)/Cl(2B)] and protons were not
generated for this. In 7, the sulfur-carbon atoms on one of the
thienyl groups are disordered over two sites. Cluster 9 co-
crystallized with half a molecule of dichloromethane, the chlorine
4.9. Computational methodology
DFT calculations were performed with the Gassian09 package
of programs [28]. The calculations were carried out with the
B3LYP functional, which utilizes the Becke three-parameter ex-
change functional (B3) [29] combined with the correlation func-
tional of Lee, Yang, and Parr (LYP) [30]. The osmium atoms were
described by StuttgarteDresden effective core potentials (ecp)
and an SDD basis set, while the 6e31G(d0) basis set was employed
for the remaining atoms. The geometry-optimized structures
were drawn with the JIMP2 molecular visualization and manip-
ulation program [31].
ꢀ
atom of which makes a close contact (3.226 A) with one of the
carbonyl oxygen atoms, O(3). For this complex, all hydrogen atoms
were located from difference maps and refined isotropically. The
asymmetric unit of 10 contains two triosmium clusters and three
molecules of dichloromethane. There are short contacts of 2.87e
Acknowledgments
This research has been partly sponsored by The Ministry of
Education, Government of the Peoples Republic of Bangladesh. SG
ꢀ
3.05 A between oxygen atoms of the carbonyl ligands while one

410
A.K. Raha et al. / Journal of Organometallic Chemistry 751 (2014) 399e411
K. Hardcastle, J. Roe, V. Vazquez, C. Roe, S. Kabir, B. Roy, S. Alam, K.A. Azam,
Coord. Chem. Rev. 190-192 (1999) 975e1002;
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(2005) 4747e4759;
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378 (2011) 307e310;
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M. Visi, J. Am. Chem. Soc. 120 (1998) 12818e12828;
(i) E. Arcia, D.S. Kolwaite, E. Rosenberg, K. Hardcastle, J. Ciurash, R. Duque,
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thanks the Commonwealth Scholarship Commission for the award
of a Commonwealth Scholarship. GH thanks The Royal Society of
Chemistry for an International Authors Award which allowed him
to complete this manuscript while visiting the University of North
Texas. MGR acknowledges financial support from the Robert A.
Welch Foundation (Grant B-1093) and the NSF (CHE-0741936). Prof.
Michael B. Hall (TAMU) is thanked for providing us a copy of his
JIMP2 program, which was used to prepare the geometry-
optimized structures reported here. We also thank Ms. Anna
Gould who was supported by a Nuffield Foundation Undergraduate
Research Bursary for the VT NMR study of [Os3(CO)8(PTh3)2(
m-
dppm)].
Appendix A. Supplementary material
CCDC 941629, 941630, 941631, 941632, 941634, 941633, 941635,
941636 and 941637 contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.
uk/data_request/cif.
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