Reactivity of triruthenium thiophyne and furyne clusters: Competitive S-C and P-C bond cleavage reactions and the generation of highly unsymmetrical alkyne ligands

Article abstract of DOI:10.1039/b806846a

The synthesis and reactivity of the thiophyne and furyne clusters [Ru ₃(CO)₇(μ-dppm)(μ₃-η²- C₄H₂E){μ-P(C₄H₃E) ₂}(μ-H)] (E = S, 4;E=O,6) is reported. Addition of P(C ₄H₃E)₃ to [Ru₃(CO) ₁₀(μ-dppm)] (1) at room temperature in the presence of Me ₃NO gives simple substitution products [Ru₃(CO) ₉(μ-dppm)(μ₃-n³-SC₄H ⁴){μ-P (C₄H₃E)₃}] (E = S, 2; E = O, 3). Mild thermolysis in the presence of further Me₃NO affords the thiophyne and furyne complexes [Ru₃(CO)₇(μ-dppm) (μ₃-η²-C₄H₂E){μ-P(C ₄H₃E)₂}(μ-H)] (E = S, 4; E = O, 6) resulting from both carbon-hydrogen and carbon-phosphorus bond activation. In each the C₄H₂E (E = S, O) ligand donates 4-electrons to the cluster and the rings are tilted with respect to the μ-dppm and the phosphido-bridged open triruthenium unit. Heating 4 at 80 °C leads to the formation of the ring-opened cluster [Ru₃(CO)₅(μ-CO) (μ-dppm)(μ₃-η³-SC₄H ₃){μ-P(C₄H₃S)₂}] (5) resulting from carbon-sulfur bond scission and carbon-hydrogen bond formation and containing a ring-opened μ₃-η³-1-thia-1,3-butadiene ligand. In contrast, a similar thermolysis of 3 affords the phosphinidene cluster [Ru₃(CO)₇(μ-dppm)(μ₃- η²-C₄H₂O){μ₃-P(C ₄H₃O)}] (7) resulting from a second phosphorus-carbon bond cleavage and (presumably) elimination of furan. Treatment of 4 and 6 with PPh₃ affords the simple phosphine-substituted products [Ru ₃(CO)₆(PPh₃)(μ-dppm)(μ₃- η²-C₄H₂E){μ-P(C₄H ₃E)₂}(μ-H)] (E = S, 8; E = O, 9). Both thiophyne and furyne clusters 4 and 6 readily react with hydrogen bromide to give [Ru ₃(CO)₆Br(μ-Br)(μ-dppm)(μ₃- η²-η¹-C₄H₂E){μ-P(C ₄H₃E)₂}(μ-H)] (E = S, 10; E = O, 11) containing both terminal and bridging bromides. Here the alkynes bind in a highly unsymmetrical manner with one carbon acting as a bridging alkylidene and the second as a terminally bonded Fisher carbene. As far as we are aware, this binding mode has only previously been noted in ynamine complexes or those with metals in different oxidation states. The crystal structures of seven of these new triruthenium clusters have been carried out, allowing a detailed analysis of the relative orientations of coordinated ligands. The Royal Society of Chemistry 2008.

Full text of DOI:10.1039/b806846a

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www.rsc.org/dalton | Dalton Transactions
Reactivity of triruthenium thiophyne and furyne clusters: competitive S–C and
P–C bond cleavage reactions and the generation of highly unsymmetrical
alkyne ligands†
Md. Nazim Uddin,a Noorjahan Begum,b Mohammad R. Hassan,a Graeme Hogarth,*c Shariff E. Kabir,*a
Md. Arzu Miah,a Ebbe Nordlander*b and Derek A. Tocher*c
Received 2nd May 2008, Accepted 1st September 2008
First published as an Advance Article on the web 30th September 2008
DOI: 10.1039/b806846a
2
The synthesis and reactivity of the thiophyne and furyne clusters [Ru3(CO)7(m-dppm)(m3-h -C4H2E){m-
P(C4H3E)2}(m-H)] (E = S, O) is reported. Addition of P(C4H3E)3 to [Ru3(CO)10(m-dppm)] (1) at room
temperature in the presence of Me3NO gives simple substitution products [Ru3(CO)9(m-dppm)-
{P(C4H3E)3}] (E = S, 2; E = O, 3). Mild thermolysis in the presence of further Me3NO affords the
2
thiophyne and furyne complexes [Ru3(CO)7(m-dppm)(m3-h -C4H2E){m-P(C4H3E)2}(m-H)] (E = S, 4;
E = O, 6) resulting from both carbon-hydrogen and carbon-phosphorus bond activation. In each the
C4H2E (E = S, O) ligand donates 4-electrons to the cluster and the rings are tilted with respect to the
m-dppm and the phosphido-bridged open triruthenium unit. Heating 4 at 80 ◦C leads to the formation
3
of the ring-opened cluster [Ru3(CO)5(m-CO)(m-dppm)(m3-h -SC4H3){m-P(C4H3S)2}] (5) resulting from
carbon-sulfur bond scission and carbon-hydrogen bond formation and containing a ring-opened
3
m3-h -1-thia-1,3-butadiene ligand. In contrast, a similar thermolysis of 3 affords the phosphinidene
2
cluster [Ru3(CO)7(m-dppm)(m3-h -C4H2O){m3-P(C4H3O)}] (7) resulting from a second
phosphorus-carbon bond cleavage and (presumably) elimination of furan. Treatment of 4 and 6 with
2
PPh3 affords the simple phosphine-substituted products [Ru3(CO)6(PPh3)(m-dppm)(m3-h -C4H2E){m-
P(C4H3E)2}(m-H)] (E = S, 8; E = O, 9). Both thiophyne and furyne clusters 4 and 6 readily react with
2
1
hydrogen bromide to give [Ru3(CO)6Br(m-Br)(m-dppm)(m3-h -h -C4H2E){m-P(C4H3E)2}(m-H)] (E = S,
10; E = O, 11) containing both terminal and bridging bromides. Here the alkynes bind in a highly
unsymmetrical manner with one carbon acting as a bridging alkylidene and the second as a terminally
bonded Fisher carbene. As far as we are aware, this binding mode has only previously been noted in
ynamine complexes or those with metals in different oxidation states. The crystal structures of seven of
these new triruthenium clusters have been carried out, allowing a detailed analysis of the relative
orientations of coordinated ligands.
made using heterodifunctional phosphines such as diphenyl(2-
Introduction
thienyl)phosphine,6–10 diphenyl(benzothienyl)phosphine,10 di(2-
thienyl)phenylphosphine,10 and tri(2-thienyl)phosphine10–14 which
are capable of introducing the thienyl, C4H3S, ligand as a result of
phosphorus-carbon bond cleavage.
The rearrangement of small organic molecules within the confines
of low-valent transition metal clusters continues to be an active
area of interest since it potentially allows insight into related trans-
formations that may occur during heterogeneous catalytic pro-
cesses. One particularly important illustration of this are attempts
to model the key steps in the metal-catalysed hydrodesulfurisation
of fossil fuels.1–5 Thiophene is a key contaminant that needs to
be removed and consequently its organometallic chemistry has
been widely studied, but it does not generally act as a good ligand
to low-valent metal clusters. Consequently, development of the
organometallic chemistry of thiophene-derived ligands has been
The coordination chemistry of diphenyl(2-thienyl)phosphine
has been especially well-developed.6 For example, Deeming and
co-workers have shown that it reacts with Re2(CO)10 to give
[Re2(CO)8(m-Ph2PC4H3S)] (A, Chart 1) in which the intact ligand
bridges the two metal atoms and this subsequently rearranges
upon heating via phosphorus-carbon bond cleavage to give
thienyl-bridged [Re2(CO)8(m-PPh2)(m-C4H3S)] (B). In contrast,
the simple addition product of Mn2(CO)10 rearranges to afford
1
5
[Mn2(CO)6(m-PPh2)(m-h :h -C4H3S)] in which the thienyl-bridge
acts as a 7-electron donor (C).6 Deeming also investigated
the reaction of diphenyl(2-thienyl)phosphine with Ru3(CO)12;7
here the major product is [Ru3(CO)9(m3-Ph2PC4H2S)(m-H)] (D),
containing a cyclometalated thienylphosphine ligand in which the
sulfur remains non-metal bound.
We recently focused our attention towards developing the
organometallic chemistry of tri(2-thienyl)phosphine and, by
way of contrast, the related tri(2-furyl)phosphine.15–16 These are
aDepartment of Chemistry, Jahangirnagar University, Savar, Dhaka 1342,
Bangladesh
bInorganic Research Group, Chemical Physics, Center for Chemistry and
Chemical Engineering, Lund University, P. O. Box 124, SE-22100 Lund,
Sweden
cDepartment of Chemistry, University College London, 20 Gordon Street,
London, UK WC1H OAJ
† CCDC reference numbers 684188–684193 and 685951. For crystallo-
graphic data in CIF or other electronic format see DOI: 10.1039/b806846a
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©

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containing highly unsymmetrical alkyne ligands which we believe
can be considered as binding in a terminal Fischer-carbene and
bridging alkylidene fashion.
Results and discussion
(a) Carbonyl substitution products
Treatment of [Ru3(CO)10(m-dppm)] (1) with tri(2-thienyl)phos-
phine and tri(2-furyl)phosphine at room temperature in the
presence of Me3NO afforded [Ru3(CO)9(m-dppm){P(C4H3S)3}]
(2) and [Ru3(CO)9(m-dppm){P(C4H3O)3}] (3) as red, air-stable
crystalline solids in 90–95% yield (Scheme 1). Both have been
fully characterized, 2 via a single-crystal X-ray diffraction analysis.
The molecular structure is shown in Fig. 1 together with selected
bond distances and angles and it is very similar to that of
a number of related [Ru3(CO)9(PR3)(m-dppm)] complexes.24 All
phosphorus atoms occupy equatorial sites and there are two short
Chart 1
capable of delivering multiple thienyl and furyl rings respec-
tively to cluster centres via phosphorus-carbon bond cleavage.
Although tri(2-furyl)phosphine has become an important ligand
in transition metal catalysis,17 related studies with low-valent
clusters remain virtually unexplored. Wong et al. have reported
formation of binuclear [Ru2(CO)6(m-C4H3O){m-P(C4H3O)2}] (E)
from the reaction of Ru3(CO)12 with tri(2-furyl)phosphine at
67 ◦C resulting from carbon-phosphorus bond cleavage and
coordination of the dissociated heteroaromatic group in a s,p-
alkenyl fashion.18 Wong’s group have also investigated the reac-
tion of tri(2-furyl)phosphine with [Ru4(CO)12(m-H)4] obtaining a
series of clusters containing furyl, furyne, phosphido- and phos-
phinidene ligands.19 More recently, we reported the synthesis of di-
and tri-substituted ruthenium clusters, [Ru3(CO)10{P(C4H3O)3}2]
and [Ru3(CO)9{P(C4H3O)3}3], and their subsequent transforma-
tion under mild conditions to dinuclear (E) and [Ru2(CO)5(m-
C4H3O){m-P(C4H3O)2}{P(C4H3O)3}] respectively via cleavage of
metal-metal and phosphorus-carbon bonds.
˚
[Ru(1)–Ru(2) = 2.8523(3), Ru(2)–Ru(3) = 2.8622(3) A] and one
˚
slightly longer [Ru(1)–Ru(3) = 2.8938(3) A] ruthenium-ruthenium
Reactions of tri(2-thienyl)phosphine with Os3(CO)12 and [(m-
H)2Os3(CO)10] leads to the formation of both simple substitution
products as well as others resulting from cyclometalation,13 related
dirhodium cyclometalation complexes also being accessible.11–12
In contrast, the only reported reactivity study of Ru3(CO)12 with
tri(2-thienyl)phosphine lead to the isolation of low yields of
[Ru3(CO)10{P(2-C4H3S)3}2] and trans-[Ru(CO)3{P(2-C4H3S)3}2];14
the latter being notable as it results from cluster fragmentation but
contains intact tri(2-thienyl)phosphine ligands.
Scheme 1
The work detailed above shows that reactions of both tri(2-
thienyl)- and tri(2-furyl)phosphines with Ru3(CO)12 are charac-
terized by cluster fragmentation. With this in mind, we turned
our attention to the reactivity of both with the diphosphine-
substituted triruthenium cluster [Ru3(CO)10(m-dppm)] (dppm =
Ph2PCH2PPh2).20 This has been shown to exhibit significantly
greater reactivity than the comparatively unreactive Ru3(CO)12,21
while the small-bite angle diphosphine ligand is also highly
effective at maintaining the integrity of the trinuclear cluster
framework. Herein we describe reactions of P(C4H3E)3 (E = O,
S) with [Ru3(CO)10(m-dppm)] leading to the facile formation of
trinuclear furyne- and thiophyne-hydride clusters the reactivity
of which has been investigated. A key finding in the latter is
the competitive nature of the activation of various E–C versus
P–C bonds within these clusters and the selective formation of
phosphinidene (E = O) and thia-1,3-butadiene (E = S) ligands,
while in no instance is the well-known self-activation of the dppm
ligand noted.21–23 We also report the formation of complexes
Fig. 1 Molecular structure of [Ru3(CO)9(m-dppm){P(C4H3S)3}] (2)
◦
˚
with selected bond lengths (A) and angles ( ): Ru(1)–Ru(2) 2.8523(3),
Ru(1)–Ru(3) 2.8938(3), Ru(2)–Ru(3) 2.8622(3), Ru(1)–P(1) 2.3366(8),
Ru(2)–P(2) 2.3232(7), Ru(3)–P(3) 2.3374(8), Ru(2)–Ru(1)–Ru(3)
59.745(8), Ru(1)–Ru(2)–Ru(3) 60.847(8), Ru(2)–Ru(3)–Ru(1) 59.407(8),
P(3)–Ru(3)–Ru(2) 159.88(2), P(3)–Ru(3)–Ru(1) 101.70(2), P(2)–Ru(2)–
Ru(1) 94.01(2), P(2)–Ru(2)–Ru(3) 152.98(2), P(1)–Ru(1)–Ru(2) 88.91(2),
P(1)–Ru(1)–Ru(3) 148.18(2), P(2)–C(10)–P(1) 111.50(14).
6220 | Dalton Trans., 2008, 6219–6230
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vectors. The latter lies opposite the monodentate phosphine
[P(3)–Ru(3)–Ru(2) = 159.88(2)◦] and the elongation results from
the trans-influence of the former. The ruthenium-phosphorus
bond distances [Ru(1)–P(1) = 2.3366(8), Ru(2)–P(2) = 2.3232(7)
˚
and Ru(3)–P(3) = 2.3374(8) A] are comparable to those found
in [Ru3(CO)9(PR3)(m-dppm)] (R = Et, Ph, Cy, Pri) in which
the phosphorus atoms are similarly bonded equatorially to the
ruthenium triangle.24
Spectroscopic data are also similar to those reported for
1
[Ru3(CO)9(PR3)(m-dppm)].24 The 31P{ H} NMR spectra of each
displays two singlets (d 16.4 and 1.9 for 2; d 16.4 and -14.3 for 3)
in an approximate 2:1 ratio showing that in solution the two ends
of the dppm ligand are equivalent. This is attributed to the rapid
fluxionality of P(C4H3E)3 (E = S, O) between equatorial positions
of the unique ruthenium atom and is similar to behavior noted
in other complexes of this type. In adopting a terminal-equatorial
coordination mode in 2–3, P(C4H3E)3 ligands serve as classic mon-
odentate phosphorus-donors. This behavior is in contrast to the re-
activity observed towards Ru3(CO)1214,18 where in bothcases mono-
substituted clusters were not isolated presumably since they un-
dergo further transformations under the reaction conditions used.
2
Fig. 2 Molecular structure of [Ru3(CO)7(m-dppm)(m3-h -C4H2S){m-P-
(b) Thiophyne and furyne complexes resulting from
phosphorus-carbon and carbon-hydrogen bond cleavage
◦
˚
(C4H3S)2}(m-H)] (4) with selected bond lengths (A) and angles ( ):
Ru(1)–Ru(3) 2.8072(4), Ru(1)–Ru(2) 2.9406(3), Ru(1)–P(1) 2.3574(8),
Ru(2)–P(2) 2.3687(8), Ru(2)–P(3) 2.3581(8), Ru(3)–P(3) 2.3862(8),
Ru(1)–C(35) 2.286(3), Ru(1)–C(38) 2.325(3), Ru(2)–C(35) 2.123(3),
Ru(3)–C(38) 2.104(3), Ru(3)–Ru(1)–Ru(2) 84.766(9), C(35)–Ru(1)–C(38)
36.04(10), C(35)–Ru(1)–Ru(3) 75.87(7), C(38)–Ru(1)–Ru(3) 47.26(8),
C(35)–Ru(1)–Ru(2) 45.84(7), C(38)–Ru(1)–Ru(2) 72.68(8), C(38)–
Ru(3)–Ru(1) 54.24(8), P(3)–Ru(2)–Ru(1) 78.373(19), P(3)–Ru(3)–Ru(1)
80.72(2), Ru(2)–P(3)–Ru(3) 109.55(3), C(38)–Ru(3)–P(3) 83.01(9),
C(37)–S(1A)–C(38) 102.3(2), C(42)–S(2)–C(39) 92.25(18), C(43)–S(3)–
C(46) 91.9(3), P(2)–C(10)–P(1) 111.85(14).
◦
Heating either 2 or 3 at 40 C in the presence of Me3NO results
2
in the clean formation of [Ru3(CO)7(m-dppm)(m3-h -C4H2E){m-
P(C4H3E)2}(m-H)] (E = S, 4; E = O, 6) (Scheme 1). Both have been
fully characterized spectroscopically and by single crystal X-ray
diffraction studies. The molecular structures of these isostructural
clusters are depicted in Fig. 2 and 3 together with selected bond
lengths and angles. Both contain an open triangular cluster
of ruthenium atoms and seven terminal carbonyls. One edge
is simultaneously bridged by the hydride (located and refined
crystallographically) and the diphosphine and these metal-metal
age occurs initially. IR and TLC monitoring of the reactions gave
no evidence of the presence of any intermediates. We speculate that
hydride clusters, [Ru3(CO)7(m-dppm){m3-(C4H2E)P(C4H3E)2}(m-
H)] (E = S, O), resulting from cyclometalation of one a ring
are initially formed since such products are the final products
of the reaction of Ph2P(C4H3S) with Ru3(CO)12.7 The absence
of observable intermediates suggests that after the initial rate-
determining cyclometalation, cleavage of the phosphorus-carbon
bond is facile.
˚
distances [Ru(1)–Ru(2) = 2.9406(3) A in 4 and Ru(2)–Ru(3) =
˚
2.9316(3) A in 6] are significantly longer than the non-hydride-
˚
˚
bridged bonds [Ru(1)–Ru(3) = 2.8072(4) A in 4 and 2.8182(4) A in
6] and also the corresponding dppm- and hydride-bridged metal-
3
=
metal edge in [Ru3(CO)6(m-dppm){m3-h -PhC N(C6H4)PPh2}(m-
25
˚
H)] of 2.870(6) A. The open-edge of the ruthenium triangle
˚
˚
[3.876 A in 4 and 3.895 A in 6] is asymmetrically bridged by the new
phosphido ligands and ruthenium-phosphorus bond distances
and angles are similar to those found in other open triruthenium
clusters28–28 including [Ru3(CO)5(m-dppm)(m3-PPh)(m-PPh2)2].26
The most interesting features of these clusters are the coor-
Both 4 and 6 exist as a mixture of two isomers in solution
(Scheme 2) probably arising from the disposition of the bridging
hydride ligand across the two inequivalent ruthenium-ruthenium
edges. The hydride region of the 1H NMR spectra are very similar
and each contains two sets of signals in an approximate 10:1 ratio;
a doublet of doublet of doublets (d -14.95 for 4a and -15.18 for
6a) and a doublet of doublets (d -14.93 for 4b and -15.16 for 6b). It
seems reasonable to suggest that in the major isomer the hydride
and dppm ligands bridge the same ruthenium-ruthenium edge
as found in the solid-state, while in the minor isomer they span
two different ruthenium-ruthenium edges. The aliphatic region of
the spectra shows four sets of multiplets for the diastereotopic
2
dination of m3-h -thiophyne and furyne ligands to the face of
the cluster, formed by the cleavage of both carbon-phosphorus
and carbon-hydrogen bonds. Both are slightly tilted on cluster
surface towards the p-coordination side being similar to those
previously observed for coordinated thiophyne in [Os3(CO)9(m3-
3
h -SC4H2)(m-H)2].29 The C(35)–C(38) and C(10)–C(11) bonds in
˚
4 and 6 of 1.427(4) and 1.416(4) A respectively are typical of
coordinated alkynes. The Ru–C p-bonding is quite symmetrical
˚
in 4 [Ru(1)–C(35) = 2.286(3) and Ru(1)–C(38) = 2.325(3) A], but
1
more asymmetric in 6 [Ru(3)–C(10) = 2.257(3) and Ru(3)–C(11) =
methylene protons and 31P{ H} NMR spectra exhibit two sets of
˚
2.389(3) A].
three doublets of doublets (d 32.5, 42.0 and 5.5 for 4a; d 39.7, 33.3
and 4.1 for 4b; d 42.8, 37.1 and -6.9 for 6a; d 39.8, 34.2 and -5.2
for 6b) which are also attributed to the presence of two isomers.
The mode of formation of 4 and 6 remains unknown and it is not
clear whether carbon-hydrogen or carbon-phosphorus bond cleav-
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Scheme 3
2
Fig. 3 Molecular structure of [Ru3(CO)7(m-dppm)(m3-h -C4H2O){m-P-
˚
(C4H3O)2}(m-H)] (6) with selected bond lengths (A) and an-
gles (◦): Ru(1)–Ru(3) 2.8182(4), Ru(2)–Ru(3) 2.9316(3), Ru(1)–P(1)
2.3758(7), Ru(2)–P(1) 2.3554(7), Ru(2)–P(2) 2.3700(7), Ru(3)–P(3)
2.3542(8), C(10)–C(11) 1.416(4), Ru(1)–C(11) 2.089(3), Ru(2)–C(10)
2.094(3), Ru(3)–C(10) 2.257(3), Ru(3)–C(11) 2.389(3), C(10)–O(8)
1.417(3), C(14)–O(9) 1.382(4), C(18)–O(10) 1.337(4), Ru(1)–Ru(3)–Ru(2)
85.256(8), C(10)–Ru(3)–C(11) 35.34(9), C(11)–Ru(1)–Ru(3) 55.92(8),
C(10)–Ru(2)–Ru(3) 50.04(7), C(10)–Ru(3)–Ru(1) 74.51(7), C(11)–
Ru(3)–Ru(1) 46.40(7), P(1)–Ru(2)–Ru(3) 76.061(19), P(2)–Ru(2)–Ru(3)
93.429(19), P(3)–Ru(3)–Ru(1) 167.90(2), Ru(2)–P(1)–Ru(1) 110.82(3),
C(13)–O(8)–C(10) 106.7(2), C(17)–O(9)–C(14) 107.1(2), C(18)–O(10)–
C(21) 105.9(3), P(2)–C(30)–P(3) 113.34(15).
3
Fig. 4 Molecular structure of [Ru3(CO)5(m-CO)(m-dppm)(m3-h -SC4H◦3)-
˚
{m-P(C4H3S)2}] (5) with selected bond lengths (A) and angles ( ):
Ru(1)–Ru(2) 2.7030(8), Ru(2)–Ru(3) 2.8656(9), Ru(1)–P(3) 2.3254(11),
Ru(2)–P(2) 2.3025(11), Ru(3)–P(3) 2.3949(11), Ru(3)–P(1) 2.4170(11),
Ru(1)–S(1) 2.4001(11), Ru(2)–S(1) 2.4647(10), Ru(1)–C(7) 2.278(3),
Ru(1)–C(8) 2.343(4), Ru(2)–C(7) 2.030(3), Ru(3)–C(7) 2.058(3),
Ru(2)–C(4) 1.914(4), Ru(3)–C(4) 2.542(4), Ru(1)–Ru(2)–Ru(3)
77.689(11), C(7)–Ru(1)–C(8) 34.97(11), S(1)–Ru(1)–Ru(2) 57.39(3),
C(7)–Ru(1)–Ru(2) 47.15(8), C(8)–Ru(1)–Ru(2) 76.11(9), P(2)–Ru(2)–
Ru(1) 143.39(3), C(7)–Ru(2)–Ru(3) 45.88(9), S(1)–Ru(2)–Ru(3)
125.67(3), P(3)–Ru(3)–Ru(2) 83.37(3), Ru(1)–P(3)–Ru(3) 95.52(3),
C(7)–Ru(2)–S(1) 82.84(10), S(1)–Ru(2)–Ru(1) 55.12(2), C(7)–Ru(3)–Ru(2)
45.10(9), Ru(1)–S(1)–Ru(2) 67.49(3), Ru(2)–C(4)–Ru(3) 78.67(12),
C(8)–C(7)–Ru(3) 137.8(3), C(8)–C(7)–Ru(1) 75.1(2), Ru(3)–C(7)–Ru(1)
107.32(14), C(7)–C(8)–Ru(1) 69.96(19), P(2)–C(19)–P(1) 118.74(18).
Scheme 2
(c) Sulfur-carbon bond cleavage: ring-opening of the
thiophyne ligand
Fig. 4 together with selected bond lengths and angles, while Fig. 5
highlights the cluster core geometry.
The importance of the enhanced reactivity of the phospho-
thiophene and phosphofuran ligands in 2 and 3 is further
demonstrated by their thermal reactions at 80◦C. Thermolysis
of 2 in refluxing benzene provided, in addition to 4 (29%),
the novel thiophyne ring-opened complex [Ru3(CO)5(m-CO)(m-
The molecule represents a unique example of an open triruthe-
nium cluster containing a capping 1-thia-1,3-butadiene ligand.
This results from the cleavage of one carbon-sulfur bond of the
coordinated thiophyne ligand and addition of the hydride to
the cleaved ligand. The thiabutadiene bridges across the Ru(1)–
Ru(2) edge through the sulfur atom [Ru(1)–S(1) = 2.4001(11),
3
dppm)(m3-h -SC4H2){m-P(C4H3S)2}] (5) in 37% yield (Scheme 3).
˚
In a separate experiment, 4 converted into 5 in 68% yield
after heating for 2.5 h in refluxing benzene. In contrast,
a similar thermolysis of 3 afforded only 6 in 94% yield,
and no evidence was obtained for the formation of a ring-
opened product. Cluster 5 was characterized by a single-crystal
X-ray diffraction analysis. The molecular structure is depicted in
Ru(2)–S(1) = 2.4647(10) A] and caps the ruthenium triangle
through C(7) via Ru–C s-bonds to two ruthenium atoms [Ru(3)–
˚
C(7) = 2.058(3) and Ru(2)–C(7) = 2.030(3) A] and a p-bond
to the third, Ru(1), through the atoms of formal carbon-carbon
˚
double bond, C(7)–C(8) of 1.390(5) A [Ru(1)–C(7) = 2.278(3),
˚
Ru(1)–C(8) = 2.343(4) A]. The other two carbon-carbon bond
6222 | Dalton Trans., 2008, 6219–6230
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Fig. 5 Different views of the orientation of the 1-thia-1,3-butadiene ligand on the Ru3 face of cluster 5.
˚
phosphido ligand, with concomitant loss of the hydride. These
may be eliminated as furan, however, we have not shown this
directly. Cluster 7 was fully characterized and a single-crystal
X-ray diffraction analyses was also carried out, the results of which
are summarised in Fig. 6 and its caption. The structure consists
of an open arrangement of three ruthenium atoms with two
metal-metal bonds [Ru(1)–Ru(2) = 2.8037(4) and Ru(1)–Ru(3) =
lengths [C(8)–C(9) = 1.479(5) and C(9)–C(10) = 1.321(6) A]
are clearly single and double bonds respectively and the diene
is cisoid (Fig. 5). Together with the diphosphine and phosphido
ligands, the remaining coordination sphere comprises five terminal
and one semi-bridging carbonyl [Ru(2)–C(4) = 1.914(4), Ru(3)–
˚
C(4) = 2.542(4) A]. The diphosphine occupies equatorial sites
on Ru(2)–Ru(3) vector which is also bridged by C(7) of the 1-
thia-1,3-butadiene ligand and the semi-bridging carbonyl. The
˚
2.8648(4) A] and a non-bonded separation [Ru(2)–Ru(3) =
˚
˚
4.038 A]. The diphosphine spans the Ru(1)–Ru(3) edge which is
open Ru(1) ◊ ◊ ◊ Ru(3) edge of 3.495 A is asymmetrically bridged
30
˚
˚
marginally longer than the comparable edge in 1 [2.834(1) A].
[Ru(3)–P(3) = 2.3949(11) and Ru(3)–P(3) = 2.3254(11) A] by the
The furylphosphinidene ligand asymmetrically caps one side of
the open ruthenium triangle; the two wingtips Ru–P distances
phosphido ligand with the diphosphine asymmetrically spanning
the Ru(2)–Ru(3) edge [Ru(3)–P(1) = 2.4170(11) and Ru(2)–P(2) =
˚
˚
˚
[Ru(2)–P(3) = 2.3083(6) A} and Ru(3)–P(3) = 2.2743(7) A]
2.3025(11) A], occupying equatorial coordination sites. Another
being significantly shorter than the hinge Ru–P distance
noticeable feature of 5 is the expansion of the P–C–P bond angle by
6.89◦ as compared to 4, possibly to accommodate the 1-thia-1,3-
butadiene ligand. This expansion is also evident from the reduction
of the Ru–Ru–Ru bond angle by 7.08◦ as compared to that in 4.
Spectroscopic data for 5 are consistent with the solid-state
structure. In addition to the resonances due to the diphosphine and
phosphido ligands, the 1H NMR spectrum contains two doublets
at d 6.67 (J = 4.8 Hz) and 3.89 (J = 5.6 Hz), and a doublet of
doublets at d 5.58 (J = 5.6, 4.8 Hz) assigned to the three protons
of the 1-thia-1,3-butadiene ligand. The 31P{ H} NMR spectrum
1
shows three doublet of doublets at d 44.4 (J = 238.3, 16.3 Hz), 41.5
(dd, J = 238.3, 75.5 Hz) and -34.5 (J = 75.5, 16.3 Hz) consistent
with the structure.
(d) Further phosphorus-carbon bond cleavage: Formation of a
phosphinidene cluster
In order to compare the chemistry of the oxygen analogue 6 with
that of 4, we investigated the thermolysis of the former under
more forcing conditions. Thus, refluxing a toluene solution of 6
2
yielded the new phosphinidene cluster [Ru3(CO)7(m-dppm)(m3-h -
2
C4H2O){m3-P(C4H3O)}] (7) in 70% yield (Scheme 4). This results
Fig. 6 Molecular structure of [Ru3(CO)7(m-dppm)(m3-h -C4H2O){m3-P-
◦
˚
(C4H3O)}] (7) with selected bond lengths (A) and angles ( ): Ru(1)–Ru(2)
2.8037(4), Ru(1)–Ru(3) 2.8648(4), Ru(1)–P(1) 2.3224(7), Ru(1)–P(3)
2.4063(6), Ru(2)–P(3) 2.3083(6), Ru(3)–P(3) 2.2743(7), Ru(3)–P(2)
2.3718(7), Ru(1)–C(9) 2.384(2), Ru(1)–C(8) 2.389(2), Ru(2)–C(9) 2.085(2),
Ru(3)–C(8) 2.091(2), Ru(2)–Ru(1)–Ru(3) 90.836(7), P(3)–Ru(1)–Ru(2)
51.916(16), P(3)–Ru(1)–Ru(3) 50.201(16), P(1)–Ru(1)–P(3) 127.81(2),
P(1)–Ru(1)–Ru(3) 82.340(16), C(8)–Ru(1)–Ru(2) 74.57(6), C(8)–Ru(1)–
Ru(3) 45.81(6), C(9)–Ru(1)–Ru(3) 74.02(6), C(9)–Ru(2)–Ru(1) 56.09(6),
C(8)–Ru(3)–Ru(1) 55.00(6), C(9)–Ru(1)–C(8) 34.46(8), C(9)–Ru(1)–P(3)
71.78(6), C(8)–Ru(1)–P(3) 71.05(6), C(9)–Ru(2)–P(3) 79.30(7), P(2)–
C(16)–P(1) 111.65(12).
from a second phosphorus-carbon bond activation of the bridging
Scheme 4
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˚
molecular structure is depicted in Fig. 7 together with selected
bond lengths and angles. It relates closely to 6 with the new
phosphine occupying an equatorial site at the previously unsubsti-
tuted ruthenium centre. This lies effectively cis to the phosphido-
bridge [P(3)–Ru(3)–P(4) 98.75(1)◦] and trans to the Ru(2)–Ru(3)
vector [P(3)–Ru(3)–Ru(2) 149.99(1)◦]. The ruthenium-phosphorus
distances involving the phosphido bridge [Ru(1)–P(4) = 2.369(2)
[Ru(1)–P(3) = 2.4063(6) A]. These ruthenium-phosphorus dis-
tances compare favorably with those found in other ruthenium
clusters where a phosphinidene ligand caps an open triruthenium
face (2.302–2.395 A).26–28 The m3-h -furyne ligand, which defines a
six-vertex polyhedron containing a furylphosphinidene fragment
occupying a basal vertex, caps the other face of the metal triangle
through C(9) to Ru(1) and C(8) to Ru(3) and also being attached in
a p-mode to C(9) and C(8). The Ru–C s-bonding distances [Ru(2)–
2
˚
˚
Ru(3)–P(4) = 2.398(2) A] are slightly longer than those observed
˚
in 6 as are the ruthenium-ruthenium distances [Ru(2)-Ru(3) =
C(9) = 2.085(2), Ru(3)–C(8) = 2.091(2) A] as well as the p-bonding
˚
˚
2.9364(8), Ru(1)-Ru(3) = 2.8490(8) A]. Other features of the two
distances [Ru(1)–C(9) = 2.384(2), Ru(1)–C(8) = 2.389(2) A] are in
structures are very similar.
good agreement with the corresponding distances in 6. This type
of coordination for the furylphosphinidene ligand has previously
been observed in the tetraruthenium clusters [Ru4(CO)12-x{m3-
P(C4H3O)2}(m3-h -C4H2O)(m-H)2] (x = 0, 2, 3).19
2
Spectroscopic data are fully consistent with the solid-state
structure. The 31P{ H} NMR spectrum contains three equal
1
intensity doublet of doublets. The strongly deshielded signal at
d 328.0 (J = 185.2, 27.0 Hz) is assigned to the furylphosphinidene
ligand and other signals at d 28.5 (J = 69.6, 27.0 Hz) and 22.8
(J = 185.2, 69.6 Hz) to the diphosphine. In addition to the phenyl
1
and methylene proton resonances of dppm ligand, the H NMR
spectrum contains five well-separated signals at d 7.18, 7.01, 6.95,
6.66, 6.51 (each integrating for 1H) assigned to the protons of
2
m3-h -C4H2O and m3-P(C4H3O) ligands.
The selective cleavage of a phosphorus-carbon bond in 6 as
compared to a sulfur-carbon bond scission seen in 4 is probably
a consequence of the relative stability of the oxygen-carbon versus
sulfur carbon bonds in these complexes. We note, however, that in
previous studies by Deeming and co-workers,7 heating cyclomet-
alated [Ru3(CO)9(m3-Ph2PC4H2S)(m-H)] with excess Ru3(CO)12
resulted in the formation of two tetranuclear phosphinidene-
capped clusters, [Ru4(CO)11(m4-PPh)(m4-C6H4)] and [Ru4(CO)11(m4-
PPh)(m4-C4H2S)]. Here two carbon-phosphorus bonds are cleaved
while the carbon-sulfur bond remains intact. Clearly this high-
lights the subtle factors affecting the relative rates of element-
carbon bond cleavage in these closely related triruthenium clusters.
A further point to note is that during all the thermal transforma-
tions of 4 and 6 no evidence was observed for any participation
of the diphosphine ligand. This is somewhat surprising as facile
carbon-hydrogen and carbon-phosphorus bond activation has
been commonly observed for trinuclear dppm-bridged group
8 complexes.21
2
Fig. 7 Molecular structure of [Ru3(CO)6(PPh3)(m-dppm)(m3-h -C4H2O)-
˚
{m-P(C4H3O)2}(m-H)] (9) with selected bond lengths (A) and angles
(◦): Ru(1)–C(58) 2.120(8), Ru(1)–P(1) 2.3481(19), Ru(1)–P(4) 2.3694(19),
Ru(1)–Ru(2) 2.9364(8), Ru(2)–C(58) 2.285(7), Ru(2)–C(59) 2.344(7),
Ru(2)–P(2) 2.3713(19), Ru(2)–Ru(3) 2.8490(8), Ru(3)–C(59) 2.071(8),
Ru(3)–P(3) 2.3472(19) Ru(3)–P(4) 2.3977(19), C(58)–Ru(1)–Ru(2)
50.64(19), P(1)–Ru(1)–Ru(2) 92.06(5), P(4)–Ru(1)–Ru(2) 77.27(5), C(58)–
Ru(2)–Ru(1) 45.83(19), C(59)–Ru(2)–Ru(1) 72.65(17), P(2)–Ru(2)–Ru(1)
90.37(5), Ru(3)–Ru(2)–Ru(1) 84.41(2), C(58)–Ru(2)–C(59) 35.5(3),
C(58)–Ru(2)–Ru(3) 73.87(19), C(59)–Ru(2)–Ru(3) 45.73(18), Ru(1)–P(4)–
Ru(3) 109.26(7), P(1)–C(19)–P(2) 112.3(4).
Spectroscopic data for 8 and 9 indicate that they are isostruc-
tural. Pertinently, the closely related pattern of the carbonyl
stretching frequencies in the IR spectra indicates that they have a
similar distribution of carbonyls. Both exist as a mixture of two
isomers in solution in approximately 10:1 ratio, which we attribute
to different hydride locations. A similar finding was made for 4
(e) Phosphine-substituted thiophyne and furyne clusters
Reactions of 4 and 6 with PPh3 in refluxing benzene afforded
2
the PPh3 derivatives [Ru3(CO)6(PPh3)(m-dppm)(m3-h -C4H2E){m-
P(C4H3E)2}(m-H)] (E = S, 8; E = O, 9) in good yields (Scheme 5).
Both were fully characterized and a single-crystal X-ray diffraction
analysis was carried out for 9. An ORTEP drawing of the
1
and 6. The 31P{ H} NMR spectra exhibit two sets of signals, each
isomer having four overlapping doublet of doublet of doublets (d
50.1, 40.8, 32.8 and 9.9 for 8a; d 47.5, 37.0 31.9 and 8.7 for 8b; d
50.3, 40.7, 35.8 and -0.1 for 9a; d 50.2, 38.1, 33.4 and -1.1 for 9b)
attributed to the four inequivalent phosphorus nuclei. Consistent
with these observations, the methylene protons of the dppm ligand
(d 4.01 and 2.60 for 8a, 3.51 and 2.80 for 8b; d 3.42 and 2.65 for 9a,
3.20 and 2.76 for 9b) and the bridging hydrides (d -14.36 for 8a; d
-14.55 for 8b and d -14.76 for 9a; d -15.0 for 9b) each exhibit two
sets of signals.
Scheme 5
6224 | Dalton Trans., 2008, 6219–6230
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(f) Reactions of thiophyne and furyne clusters with HBr: synthesis
of highly asymmetric alkyne complexes
Oxidative-addition of HBr to clusters often results in the net
addition of 4-electrons with concomitant opening of two metal-
metal bonds or loss of two carbonyls.31 Bubbling HBr gas through
thf solutions of 4 or 6 lead to an immediate color change
and the isolation after chromatography of the new triruthe-
2
1
nium clusters [Ru3(CO)6Br(m-Br)(m-dppm)(m3-h -h -C4H2E){m-
P(C4H3E)2}(m-H)] (E = S, 10; E = O, 11) in moderate yields.
Both were characterized by spectroscopic and analytical data but
their precise nature only became clear from a single-crystal X-
ray diffraction analysis of 11. The molecular structure of 11 is
depicted in Fig. 8 together with selected bond lengths and angles.
The molecule consists of an open arrangement of ruthenium atoms
with the expected bridging diphosphine, hydride and phosphido
ligands together with one bridging and one terminal bromide. The
hydride ligand was crystallographically located (refined) across the
Ru(2)–Ru(3) edge, lying trans to carbonyl groups CO(3) and CO(5)
and bent down towards the opposite face of the triangle occupied
˚
by the furyne. The Ru(2)–Ru(3) bond distance of 2.9379(5) A
is significantly shorter compared to the corresponding distances
in 6. The terminal bromide is equatorially coordinated [Ru(1)–
2
1
Fig. 8 Molecular structure of [Ru3(CO)6Br(m-Br)(m-dppm)(m3-h -h -
C4H2O){m-P(C4H3O)2}(m-H)] (11) with selected bond lengths
(A) and angles (◦): Ru(1)–C(11) 2.079(4), Ru(1)–P(3) 2.3098(12),
˚
˚
Br(1) = 2.6197(6) A]. The second bromide asymmetrically spans
Ru(1)–Br(2) 2.5588(6), Ru(1)–Br(1) 2.6197(6), Ru(2)–C(10) 2.196(4),
Ru(2)–P(3) 2.3815(12), Ru(2)–P(1) 2.4082(12), Ru(2)–Ru(3) 2.9379(5),
Ru(3)–C(10) 2.148(4), Ru(3)–P(2) 2.2859(12), Ru(3)–Br(2) 2.6212(6),
Br(2)–Ru(1)–Br(1) 91.77(2), P(3)–Ru(1)–Br(2) 84.51(3), P(3)–Ru(1)–Br(1)
173.64(3), P(3)–Ru(2)–P(1) 177.60(4), P(3)–Ru(2)–Ru(3) 88.58(3), P(1)–
Ru(2)–Ru(3) 90.69(3), Br(2)–Ru(3)–Ru(2) 98.243(17), Ru(1)–Br(2)–Ru(3)
102.127(19), Ru(1)–P(3)–Ru(2) 112.14(5), C(10)–Ru(2)–Ru(3) 46.77(11),
C(10)–Ru(3)–Ru(2) 48.14(12), Ru(3)–C(10)–Ru(2) 85.10(15), P(2)–C(22)–
P(1) 110.1(2).
the open Ru(1)–Ru(3) edge [Ru(1)–Br(2) = 2.5588(6), Ru(3)–
˚
Br(2) = 2.6212(6) A], while the phosphido ligand asymmetrically
bridges the second open edge, namely Ru(1)–Ru(2) [Ru(1)–P(3) =
˚
2.3098(12), Ru(2)–P(3) 2.3815(12) A].
Perhaps the most striking feature of 11 is the nature of the
furyne ligand which is now quite different to that found in
6. While it still spans all three ruthenium atoms so as to cap
one face of the triruthenium core it binds very asymmetrically
lying approximately perpendicular to the ruthenium-ruthenium
bonded edge (Fig. 9). One of the carbons, C(10), bridges this
edge slightly asymmetrically [Ru(2)–C(10) = 2.196(4) and Ru(3)–
˚
single metal atom. The Ru(1)–C(11) bond distance of 2.079(4) A
is similar to the ruthenium-carbon s bond distances in 6 while
˚
˚
C(10) = 2.148(4) A]. This is bound to a further carbon, C(11), the
distances of 3.009 and 3.178 A to Ru(2) and Ru(3) respectively are
˚
carbon-carbon bond length of 1.435(6) A is significantly greater
clearly non-bonding. The furyne ring has clear double and single
bond character as shown by the C(11)–C(12) and C(12)–C(13)
˚
than that found in 6 (1.416(4) A) and other alkyne complexes
described in this paper. This second carbon is now bound to a
˚
distances of 1.413(6) and 1.353(6) A.
Fig. 9 Two views of the central core of 11 highlighting the relative positions of furyne and ruthenium atoms and the octahedral nature of Ru(1).
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In light of these metric parameters, we favour the coordination
mode shown in Scheme 6 for the furyne binding in 11. Hence, the
ligand can be considered as a hybrid bridging-terminal carbene;
one carbon binding to a ruthenium atom in a terminal fashion
while the second bridges a ruthenium-ruthenium bond. While the
binding of alkynes to low-valent clusters is well-documented32 as
far as we are aware this type of alkyne binding is extremely rare
and has previously been confined to heterobimetallic complexes
containing metals in significantly different oxidation states,33 or
ynamine complexes.34–38 The alkyne binding in 11 most closely
doublet of doublets (d -11.87 for 10; -11.85 for 11) and their
mass spectra confirm the stoichiometry with molecular ion peaks
being observed in each case (m/z 1297 for 10 and 1249 for 11).
Unfortunately due to the relatively small amounts of 10 and 11 we
have been unable to acquire high quality 13C NMR data in order
to establish the electronic characteristics of the carbon atoms of
the alkyne ligand.
Conclusions
2
1
resembles that in [Os3(CO)9(m-H)2{m3-h -h -HC–C(NEt2)}] (F)
which can be prepared from the reaction of [Os3(CO)9(m-H)(m3-
This paper demonstrates that both tri(2-furyl)phosphine and
tri(2-thienyl)phosphine are versatile synthons for a series of new
triruthenium clusters. The transformation of 2 into 4 and 5 rep-
resents a previously unprecedented cluster-promoted sequential
activation of carbon-hydrogen, carbon-phosphorus and carbon-
sulfur bonds of coordinated tri(2-thienyl)phosphine ligand leading
2
1
h -h -C2H)] with diethylamine,38 or upon heating the alkylidyne
1
37
=
complex [Os3(CO)9(m-H)2{m3-h -C-CH( NEt2)}]. Adams and
Tanner formulated the ynamine ligand in F as a combination of
terminal and bridging carbene ligands and our current data concur
with this approach. It is noteworthy that in F and other ynamine
complexes, the amine group is bound to the terminally bonded
carbon, however in both 10–11 the electronegative heteroatom is
bound to the bridging carbene carbon.
3
to a ring-opened m3-h -1-thia-1,3-butadiene ligand. In contrast,
while the transformation of 3 into 6 follows similar phosphorus-
carbon and carbon-hydrogen bond activation processes, ring-
opening of the coordinated furyne ligand in 6 does not occur
under more forcing conditions. Rather the phosphinidene cluster
7 results from a further carbon-phosphorus bond activation of
the bridging phosphido ligand. This difference in reactivity can be
rationalised in terms of the strong carbon-oxygen versus carbon-
sulfur bond.
Addition of hydrogen bromide to both thiophyne and furyne
clusters results in the formation of new alkyne clusters in which
the hydrocarbon ligand binds highly asymmetrically to the three
metal atoms. We favour a bonding picture in which the terminally
bonded carbon acts like a Fischer-carbene and the second carbon
a bridging alkylidene. This then suggests that the carbon-carbon
interaction is best described as a single bond. We are still
developing this bonding picture using DFT calculations40 and
hope to report the details of these in the near future. The synthesis
of 10 and 11 opens up the possibility of exploring the chemistry of
theseinterestingcompounds, andworkinthisdirectioniscurrently
underway in our laboratories. In this context we note that there
are a small number of examples of related osmium clusters bearing
terminally bonded carbene ligands41,42 and these have been shown
to display high reactivity.43–46 We are currently investigating the
reactivity of 10 and 11 and will report on these in the near future.
Scheme 6
The coordination geometry of Ru(1) is octahedral with cis-
carbonyls and cis-bromides, one carbonyl lying trans to C(11)
and the terminal bromide lying trans to the phosphido-bridge.
Experimental
Ruthenium-carbon bonds in terminal alkylidene complexes tend
39
˚
to be of the order 1.85–1.90 A, but these are commonly five-
Methods and materials
coordinate and cannot be directly compared to 6. With this model
in mind, we also note the significant elongation of the carbonyl
All reactions were performed under a nitrogen atmosphere.
Reagent grade solvents were dried by the standard procedures
and were freshly distilled prior to use. [Ru3(CO)10(m-dppm)] (1)
was prepared according to the literature.47 Tri(2-thienyl)phosphine
and tri(2-furyl)phosphine were purchased from Across and used
as received. Preparative thin-layer (TLC) plates were prepared
from silica gel (Kieselgel DGF254). Infrared spectra were recorded
on a Shimadzu FTIR 8101 spectrophotometer. NMR spectra
were recorded on Varian Unity Plus 500 and Bruker DPX 400
instruments. The chemical shifts were referenced to residual
˚
trans to C(11) [Ru(1)–C(2) 1.960(5) A] as compared to that trans
˚
to the bridging bromide [Ru(1)–C(1) 1.858(6) A], and that the
˚
terminal bromide distance [Ru(1)–Br(1) = 2.6197(6) A] is longer
˚
than that to the bridging bromide [Ru(1)–Br(2) = 2.5588(6) A].
The spectroscopic data of 11 indicate that its solid-state
structure is maintained in solution and data for 10 indicate that
1
it is isostructural. The 31P{ H}NMR spectra exhibit two doublets
[d 48.4 (J = 70.4 Hz), -9.8 (J = 91.6 Hz for 10; d 48.3 (J =
64.4 Hz), -10.10 (J = 85.6 Hz) for 11] and a doublet of doublets
[d 21.7 (J = 70.4, 91.6 Hz) for 10; d 22.1 (J = 64.4, 85.6 Hz)
for 11] consistent with their solid-state structures. The hydride
1
solvent resonances or external 85% H3PO4 in H and 31P NMR
spectra as appropriate. Elemental analyses were performed by
Microanalytical Laboratories, University College London. Fast
1
region of the H NMR spectra of both contains an overlapping
6226 | Dalton Trans., 2008, 6219–6230
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atom bombardment mass spectra were obtained on a JEOL SX-
102 spectrometer using 3-nitrobenzyl alcohol as matrix and CsI as
calibrant.
the residue chromatographed by TLC on silica gel. Elution with
hexane/CH2Cl2 (6:4, v/v) developed two bands. The first band
gave 4 (27 mg, 29%) while the band [Ru3(CO)5(m-CO)(m-dppm)(m3-
3
h -SC4H3){m-P(C4H3S)2}] (5) (35 mg, 37%) as red crystals after
recrystallisation from CH2Cl2/hexane at 4 ◦C. Likewise, refluxing
a benzene solution (20 mL) of 4 (30 mg, 0.026 mmol) for 2.5 h
yielded 5 (20 mg, 68%) and some unconverted starting material
(7 mg, 23%). Calc. for C43H31O6P3Ru3S3: C, 45.46; H, 2.75. Found:
C, 45.72; H, 2.93%. IR (nCO, CH2Cl2): 2029 s, 2006 vs, 1983 vs,
1943 s, 1844 w cm-1. 1H NMR (CDCl3): d 7.62 (m, 2H), 7.44 (m,
8H), 7.29 (s, 3H), 7.14 (m, 13H), 6.67 (d, J = 4.8 Hz, 1H), 5.58
(dd, J = 5.6, 4.8 Hz, 1H) 3.89 (d, J = 5.6 Hz, 1H), 2.83 (m,
Syntheses
[Ru3(CO)9(l-dppm){P(C4H3S)3}] (2). To a dichloromethane
solution (30 cm3) of [Ru3(CO)10(m-dppm)] (1) (100 mg,
0.103 mmol) and P(C4H3S)3 (36 mg, 0.128 mmol) was added
dropwise a dichloromethane solution (15 cm3) of Me3NO (8 mg,
0.103 mmol). The reaction mixture was stirred at room tempera-
ture for 1.5 h during which time the color changed from orange
to red. The solution was filtered through a short silica column
(2 cm) and the solvent from the filtrate was removed under reduced
pressure. The residue was recrystallised from hexane/CH2Cl2 at
4 ◦C to give [Ru3(CO)9(m-dppm){P(C4H3S)3}] (2) (113 mg, 90%) as
red crystals. Calc. for C46H31O9P3Ru3S3: C, 45.28; H, 2.56. Found:
C, 45.51; H, 2.65%. IR (nCO, CsH2Cl2) 2055 w, 1995 vs, 1979 vs,
1945 m cm-1. 1H NMR (CDCl3): d 7.53 (m, 3H), 7.50 (m, 3H), 7.33
1
1H), 2.20 (m, 1H). 31P{ H} NMR (CDCl3): d 44.4 (dd, J = 238.1,
16.3 Hz,1P), 41.5 (dd, J = 75.5, 238.1 Hz 1P), -34.5 (dd, J = 75.5,
16.3 Hz, 1P). FAB MS: m/z 1137 (M+).
[Ru3(CO)7(l-dppm)(l3-g2-C4H2O){l-P(C4H3O)2}(l-H)]
(6).
A
dichloromethane solution (40 cm3) of [Ru3(CO)9(m-
dppm){P(C4H3O)3}] (3) (100 mg, 0.085 mmol) and Me3NO
(21 mg, 0.28 mmol) was refluxed for 34 h during which time the
colour changed from red to yellow. Analytical TLC indicated
complete conversion to a new product. The solvent was removed
in vacuo and the residue washed with cold acetone to give [Ru3-
1
(m, 20H), 7.12 (m, 3H), 4.20 (t, J = 10.4 Hz, 3H). 31P{ H} NMR
(CDCl3): d 16.4 (s, 2P), 1.9 (s, 1P). FAB MS: m/z 1221 (M+).
[Ru3(CO)9(l-dppm){P(C4H3O)3}] (3). A similar reaction to
that above using 1 (100 mg, 0.103 mmol), P(C4H3O)3 (30 mg,
0.128 Me3NO (8 mg, 0.103 mmol) afforded [Ru3(CO)9(m-
dppm){P(C4H3O)3}] (3) (115 mg, 95%) as red crystals. Calc. for
C46H31O12P3Ru3: C, 47.15; H, 2.67. Found: C, 47.38; H, 2.90%. IR
(nCO, CH2Cl2) 2057 w, 1996 vs, 1981 vs, 1943 m cm-1. 1H NMR
(CDCl3): d 7.65 (s, 3H), 7.34 (m, 20H), 6.70 (m, 3H), 6.43 (m, 3H),
2
(CO)7(m-dppm)(m3-h -C4H2O){m-P(C4H3O)2}(m-H)] (6) (88 mg,
94%) as yellow crystals after recrystallisation from hexane/CH2Cl2
at 4◦C. A similar thermolysis of [Ru3(CO)9(m-dppm){P(C4H3O)3}]
(2) (100 mg, 0.085 mmol) in refluxing benzene (30 mL) for 1 h
followed by similar work up afforded 6 in high yield. Calc. for
C43H31O10P3Ru3: C, 46.79; H, 2.83. Found: C, 46.98; H, 2.96%. IR
(nCO, CH2Cl2): 2058 vs, 2038 vs, 2000 vs, 1993 vs, 1947 w cm-1.
1H NMR (CDCl3): major isomer (6a), d 7.83 (m, 1H), 7.70 (m,
4H), 7.45 (m, 6H), 7.19 (m, 8H), 6.97 (m, 3H), 6.60 (m, 3H), 6.36
(m, 2H), 6.24 (m, 1H), 3.25 (m, 1H), 2.64 (m, 1H), -15.18 (ddd,
1
4.21 (t, J = 10.2 Hz, 3H). 31P{ H} NMR (CDCl3): d 16.4 (s, 2P),
-14.3 (s, 1P). FAB MS: m/z 1173 (M+).
[Ru3(CO)7(l-dppm)(l3-g2-C4H2S){l-P(C4H3S)2}(l-H)] (4).
A
dichloromethane solution (30 cm3) of 2 (100 mg, 0.082 mmol) and
Me3NO (20 mg, 0.267 mmol) was refluxed 40 h during which
time the color changed from red to yellow. The solvent was
removed under reduced pressure and the residue chromatographed
by TLC on silica gel. Elution with hexane/CH2Cl2 (3:2, v/v)
developed two bands. The first band gave [Ru3(CO)7(m-dppm)(m3-
1
J = 11.2, 6.0 Hz, 1H). 31P{ H} NMR (CDCl3): d 42.8 (dd, J =
216.0, 122.0 Hz, 1P), 37.1 (dd, J = 122.0, 17.0 Hz, 1P), -6.9 (dd,
J = 216.0, 17.0 Hz, 1P); minor isomer (6b), d 7.78 (m, 1H), 7.71
(m, 4H), 7.54 (m, 6H), 7.14 (m, 8H), 7.02 (m, 3H), 7.90 (m, 3H),
6.80 (m, 2H), 6.25 (m, 1H), 3.04 (m, 1H), 2.74 (m, 1H), -15.16
2
1
(dd, J = 16.0, 17.2 Hz, 1H). 31P{ H} NMR (CDCl3): d 39.8 (dd,
h -C4H2S){m-P(C4H3S)2}(m-H)] (4) (55 mg, 60%) as pale yellow
crystals after recrystallisation from CH2Cl2/hexane at 4 ◦C. Calc.
for C43H31O7P3Ru3S3: C, 44.83; H, 2.71. Found: C, 44.98; H, 2.84.
IR (nCO, CH2Cl2): 2057 vs, 2036 vs, 2000 vs, 1991 vs, 1943 w cm-1.
1H NMR (CDCl3): major isomer (4a), d 7.82 (d, J = 4.0 Hz, 1H),
7.69 (m, 4H), 7.50 (m, 6H), 7.34 (m, 2H), 7.20 (m, 3H), 7.13 (m,
5H), 7.00 (m, 2H), 6.87 (m, 2H), 6.82 (d, J = 4.0 Hz, 1H), 6.48
(m, 2H), 3.77 (m, 1H), 2.77 (m, 1H) -14.95 (ddd, J = 16.0, 10.2,
J = 216.2, 104.7 Hz, 1P), 34.2 (dd, J = 104.7, 18.8 Hz, 1P), -5.2
(dd, J = 216.2, 18.8 Hz, 1P). FAB MS: m/z 1105 (M+).
[Ru3(CO)7(l-dppm)(l3-g2-C4H2O){l3-P(C4H3O)}] (7). A so-
lution of 6 (30 mg, 0.027 mmol) in toluene (25 mL) was refluxed for
4.5 h. A similar chromatographic separation to that above afforded
2
6 (5 mg) and [Ru3(CO)7(m-dppm)(m3-h -C4H2O){m3-P(C4H3O)}]
1
8.0 Hz, 1H). 31P{ H} NMR (CDCl3): d 42.0 (dd, J = 224.9, 8.9 Hz,
(7) as yellow crystals (20 mg, 70%) after recrystallisation from
hexane/CHCl3 at 4 ◦C. Calc. for C40H27O9P3Ru3: C, 45.85; H,
2.60. Found: C, 46.05; H, 2.81. IR (nCO, CH2Cl2) 2062 vs, 2009
vs, 1995 s, 1975 s, 1958 s cm-1. 1H NMR (CDCl3): d 7.70 (m, 5H),
7.39 (m, 5H), 7.28 (m, 5H), 7.18 (d, J = 2.0 Hz, 1H), 7.13 (m, 5H),
7.01 (d, J = 1.5, 1H), 6.95 (d, J = 2.0 Hz, 1H), 6.66 (d, J = 2.0 Hz,
1P), 33.2 (dd, J = 76.8, 8.9 Hz, 1P), 5.5 (dd, J = 224.9, 76.8 Hz,
1P); minor isomer (4b), d 7.78 (d, J = 4.0 Hz, 1H), 7.65 (m, 4H),
7.45 (m, 6H), 7.31 (m, 2H), 7.18 (m, 3H), 7.12 (m, 5H), 6.96 (m,
2H) 6.84 (m, 2H), 6.79 (d, J = 4.0 Hz, 1H), 6.41 (m, 2H), 2.89 (m,
1H), 2.56 (m, 1H), -14.93 (dd, J = 16.4, 16.0 Hz, 1H). 31P{ H}
1
1
1H), 6.51 (dd, J = 1.5, 2.0 Hz, 1H), 4.20 (m, 2H). 31P{ H} NMR
NMR (CDCl3): d 39.7 (dd, J = 230.2, 8.2 Hz, 1P), 32.5 (dd, J =
86.4, 8.2 Hz, 1P), 4.1 (dd, J = 230.2, 86.4 Hz, 1P) 4b. The second
band gave unconsumed 2 (4 mg). FAB MS: m/z 1153 (M+).
(CDCl3): d 328.0 (dd, J = 185.2, 27.0 Hz, 1P), 28.5 (dd, J = 69.6,
27.0 Hz, 1P), 22.8 (d, J = 185.2, 69.6, Hz, 1P). FAB MS: m/z 1049
(M+).
[Ru3(CO)5-(l-CO)(l-dppm)(l3-g3-SC4H3){l-P(C4H3S)2}] (5).
A benzene solution (30 cm3) of 2 (100 mg, 0.082 mmol) was heated
to reflux for 3.5 h during which time the colour changed from red
to deep red. The solvent was removed under reduced pressure and
[Ru3(CO)6(PPh3)(l-dppm)(l3-g2-C4H2S){l-P(C4H3S)2}(l-H)]
(8). PPh3 (12 mg, 0.046 mmol) was added to a solution of 4
(50 mg, 0.043 mmol) in 25 cm3 of benzene. The reaction mixture
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2
was heated to reflux for 3 h. After the mixture was cooled,
the solvent was removed in vacuo. The product was separated
by TLC using a 7:3 hexane/CH2Cl2 solvent mixture to yield
aration afforded [Ru3(CO)6Br(m-Br)(m-dppm)(m3-h -C4H2O){m-
P(C4H3O)2}(m-H)] (11) (9 mg, 51%) as yellow crystals af-
ter recrystallisation from hexane/CHCl3 at 25 ◦C. Calc. for
C43H31Br2O9P3Ru3: C, 41.39; H, 2.50. Found: C, 41.62; H, 2.76.
IR (nCO, CH2Cl2) 2031 w, 2014 vs, 1974 s, 1956 s cm-1. 1H NMR
(CDCl3): d 8.57 (s, 1H), 7.44 (s, 1H), 7.60 (m, 3H), 7.54–7.32 (m,
13H), 7.16–7.01 (m, 6H), 6.66 (s, 1H) 6.50 (s, 1H), 6.35 (s, 1H),
4.45 (m, 1H), 3.71 (s, 1H), 2.95 (m, 1H), -11.85 (dd, J = 12.8,
2
[Ru3(CO)6(PPh3)(m-dppm)(m3-h -C4H2S){m-P(C4H3S)2}(m-H)] (8)
(30 mg, 73%) as yellow crystals from hexane/CH2Cl2 at 4◦C. Calc.
for C61H46O6P4Ru3S3: C, 52.40; H, 3.32. Found: C, 52.69; H, 3.47.
IR (nCO, CH2Cl2) 2057 w, 2015 vs, 1973 s, 1954 s cm-1. 1H NMR
(CDCl3): major isomer (8a) d 7.81 (m, 2H), 7.57 (m, 6H), 7.44 (m,
4H), 7.35 (m, 20H), 7.16 (m, 6H), 7.01 (m, 2H), 6.87 (m, 1H), 6.65
(m, 1H), 6.09 (m, 1H), 4.01 (m, 1H), 2.60 (m, 1H), -14.36 (m, 1H).
8.8 Hz, 1H). 31P{ H} NMR (CDCl3): d 48.3 (d, J = 64.4 Hz, 1P),
1
22.1 (dd, J = 85.6, 64.4 Hz, 1P), -10.10 (d, J = 85.6 Hz, 1P). MS
(FAB): m/z 1249 (M+).
1
31P{ H} NMR (CDCl3): major isomer (8a) d 50.1 (m, 1P), 40.8 (m,
1
1P), 32.8 (m, 1P), 9.9 (m, 1P); H NMR (CDCl3): minor isomer
(8b) d 7.78 (m, 2H), 7.66 (m, 6H), 7.47 (m, 4H), 7.22 (m, 20H),
Crystallography†
7.11 (m, 6H), 6.92 (m, 2H), 6.57 (m, 1H), 6.31 (m, 1H), 6.19 (m,
1
1H), 3.51 (m, 1H), 2.80 (m, 1H), -14.55 (m, 1H). 31P{ H} NMR
Single crystals of 2, 4–7, 9 and 11 suitable for X-ray diffraction were
grown by slow diffusion of hexane into a dichloromethane solution
at 4 ◦C. All geometric and crystallographic data 2, 4–7, 9 and 11
were collected at 150 K on a Bruker SMART APEX CCD diffrac-
(CDCl3): minor isomer (8b) d 47.5 (m, 1P), 37.0 (m, 1P), 31.9 (m,
1P), 8.7 (m, 1P). FAB MS: m/z 1399 (M+).
[Ru3(CO)6(PPh3)(l-dppm)(l3-g2-C4H2O){l-P(C4H3O)2}(l-H)]
˚
tometer using Mo-Ka radiation (l = 0.71073 A). Data reduction
(9).
A similar reaction to that above using 6 (60 mg,
and integration was carried out with SAINT+ and absorption
corrections were applied using the program SADABS.48 Structures
were solved by direct methods and developed using alternating
cycles of least-squares refinement and difference-Fourier synthesis.
All non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were placed in the calculated positions and their thermal
parameters linked to those of the atoms to which they were
attached (riding model). The SHELXTL PLUS V6.10 program
package was used for structure solution and refinement.49 Final
difference maps did not show any residual electron density of
stereochemical significance. The details of the data collection and
structure refinement are given in Table 1.
0.054 mmol) and PPh3 (15 mg, 0.057 mmol) in benzene
(25 cm3) followed by similar work-up and chromatographic
2
separation afforded [Ru3(CO)6(PPh3)(m-dppm)(m3-h -C4H2O){m-
P(C4H3O)2}(m-H)] (9) (50 mg, 68%) as yellow crystals after recrys-
tallisation from hexane/CH2Cl2 at 4 ◦C. Calc. for C61H46O9P4Ru3:
C, 54.27; H, 3.43. Found: C, 54.42; H, 3.67. IR (nCO, CH2Cl2)
1
2031 w, 2014 vs, 1974 s, 1956 s cm-1. H NMR (CDCl3): major
isomer (9a) d 7.56 (m, 5H), 7.12 (m, 25H), 6.84 (m, 4H), 6.67 (m,
3H), 6.38 (m, 2H), 6.15 (m, 1H), 5.96 (m, 2H), 5.57 (m, 1H), 3.42
1
(m, 1H), 2.65 (m, 1H), -14.76 (m, 1H). 31P{ H} NMR (CDCl3):
major isomer (9a) d 50.3 (m, 1P), 40.7 (m, 1P), 35.8 (m, 1P), -0.1
(m, 1P). 1H NMR (CDCl3): maior isomer (9b) d 7.76 (m, 4H), 7.38
(m, 4H), 7.21 (m, 25H), 6.94 (m, 3H), 6.89 (m, 2H), 6.42 (m, 2H)
6.20 (m, 1H), 5.87 (m, 1H), 5.64 (m, 1H), 3.20 (m, 1H), 2.76 (m,
Acknowledgements
1
1H), -15.0 (m, 1H). 31P{ H} NMR (CDCl3): minor isomer (9b) d
M.N.U. thanks Hajee Mohammad Danesh Science and Technol-
ogy University for study leave to work at Jahangirnagar University.
S.E.K. acknowledges The Royal Society (London) for a fellowship
to work at University College London and Jahangirnagar Univer-
sity for sabbatical leave. N.B. thanks Sher-e-Bangla Agricultural
University for leave to work at Lund University. This research
has been sponsored by the Swedish International Development
Agency (SIDA) via the Swedish Research Links programme and
the Swedish Research Council (VR).
50.2 (m, 1P), 38.1 (m, 1P), 33.4 (m, 1P), -1.1 (m, 1P). FAB MS:
m/z 1351 (M+).
[Ru3 (CO)6Br(l-Br)(l-dppm)(l3 -g2 -C4H2S){l-P(C4H3S)2 }(l-
H)] (10). Hydrogen bromide gas was bubbled through a THF
solution (12 cm3) of 4 (20 mg, 0.017 mmol) for 1 min. and
immediately the color changed from pale yellow to yellow. An-
alytical TLC indicated complete consumption of 4 and formation
of a single product. Removal of solvent under reduced pressure
and chromatographic separation of the residue on silica TLC
plates eluting with hexane/CH2Cl2 gave [Ru3(CO)6Br(m-Br)(m-
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6230 | Dalton Trans., 2008, 6219–6230
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