CO substitution in HRu3(CO)10(μ-COMe) by the unsaturated diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd): Synthesis and reactivity studies of the face-capped cluster Ru3(CO)7(μ3-COMe)[μ-P(Ph)C{double bond, long}C(PPh2)C(O)CH2C(O)]

Article abstract of DOI:10.1016/j.jorganchem.2008.04.007

The reaction of the methylidyne-bridged cluster HRu₃(CO)₁₀(μ-COMe) (1) with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) and Me₃NO furnishes HRu₃(CO)₈(μ-COMe)(bpcd) (2) and HRu₃(CO)₈(Ph₂PH)[μ-PPh₂C{double bond, long}CC(O)CH₂C(O)] (3) as the major and minor products, respectively. The ¹H and ³¹P NMR data indicate that the bpcd ligand in 2 is chelated to one of the ruthenium atoms that is bridged by the hydride and methylidyne ligands. Thermolysis of 2 is accompanied by P-Ph bond cleavage and elimination of benzene to yield Ru₃(CO)₇(μ₃-COMe)[μ-P(Ph)C{double bond, long}C(PPh₂)C(O)CH₂C(O)] (4). Compound 4 consists of a triangular ruthenium core that is face-capped by μ₃-COMe methylidyne and μ-P(Ph)C{double bond, long}C(PPh₂)C(O)CH₂C(O) phosphido ligands. The kinetics for the conversion of 2 → 4 have been measured in toluene solvent over the temperature range 320-343 K, and based on the observed activation parameters and the inhibitory effect of added CO on the reaction, a rate-limiting step involving a dissociative loss of CO is supported. Heating 4 in the presence of H₂ afforded the phosphinidene-capped cluster H₃Ru₃(CO)₇(μ₃-PPh)[μ-C{double bond, long}C(PPh₂)C(O)CH₂C(O)] (5). Crystallographic analysis of 5 has confirmed the loss of the methylidyne moiety and the cleavage of the phosphido PhP-C(dione) bond, and the presence of three edge-bridging hydrides is supported by ¹H NMR spectroscopy. The reaction of 4 with added PPh₃ and PMe₃ has been investigated; the uptake of a single phosphine ligand occurs regiospecifically at one of the phosphido-bound ruthenium centers to give Ru₃(CO)₆L(μ₃-COMe)[μ-P(Ph)C{double bond, long}C(PPh₂)C(O)CH₂C(O)] (PPh₃, 6; PMe₃, 7). Compound 6 contains 48e- and exhibits a structural motif similar to that found in 4. Compound 7 readily adds a second PMe₃ ligand to yield the bis-substituted cluster Ru₃(CO)₆(PMe₃)₂(μ₂-COMe)[μ-P(Ph)C{double bond, long}C(PPh₂)C(O)CH₂C(O)] (8). The solid-state structure of 8 confirms the loss of two ruthenium-ruthenium bonds and the conversion of the original face-capping μ₃-COMe ligand to a μ₂-COMe moiety that tethers two non-bonding ruthenium centers. The two PMe₃ ligands in 8 coordinate to the same ruthenium center, and the 9e- P(Ph)C{double bond, long}C(PPh₂)C(O)CH₂C(O) ligand binds all three ruthenium atoms through the phosphine, phosphido, alkene, and carbonyl moieties. Near-UV irradiation of 8 leads to loss of CO and polyhedral contraction of the triruthenium frame to yield the 48e- cluster Ru₃(CO)₅(PMe₃)₂(μ₃-COMe)[μ-P(Ph)C{double bond, long}C(PPh₂)C(O)CH₂C(O)] (9).

Full text of DOI:10.1016/j.jorganchem.2008.04.007

Journal of Organometallic Chemistry 693 (2008) 2327–2337
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
CO substitution in HRu3(CO)10(l-COMe) by the unsaturated diphosphine
ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd):
Synthesis and reactivity studies of the face-capped cluster
Ru3(CO)7(l3-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)]
b
b
b,
Simon G. Bott a, , Huafeng Shen , Shih-Huang Huang , Michael G. Richmond
*
*
a Department of Chemistry, University of Houston, Houston, TX 77004, United States
b Department of Chemistry, University of North Texas, Denton, TX 76203, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of the methylidyne-bridged cluster HRu3(CO)10(l-COMe) (1) with the diphosphine ligand
4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) and Me3NO furnishes HRu3(CO)8
(l-COMe)(bpcd) (2) and HRu3(CO)8(Ph2PH)[l-PPh2C@CC(O)CH2C(O)] (3) as the major and minor prod-
ucts, respectively. The 1H and 31P NMR data indicate that the bpcd ligand in 2 is chelated to one of the
ruthenium atoms that is bridged by the hydride and methylidyne ligands. Thermolysis of 2 is accompa-
nied by P–Ph bond cleavage and elimination of benzene to yield Ru3(CO)7(l3-COMe)
[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (4). Compound 4 consists of a triangular ruthenium core that is face-
capped by l3-COMe methylidyne and l-P(Ph)C@C(PPh2)C(O)CH2C(O) phosphido ligands. The kinetics
for the conversion of 2 ? 4 have been measured in toluene solvent over the temperature range
320–343 K, and based on the observed activation parameters and the inhibitory effect of added CO on
the reaction, a rate-limiting step involving a dissociative loss of CO is supported. Heating 4 in the pres-
ence of H2 afforded the phosphinidene-capped cluster H3Ru3(CO)7(l3-PPh)[l-C@C(PPh2)C(O)CH2C(O)]
(5). Crystallographic analysis of 5 has confirmed the loss of the methylidyne moiety and the cleavage
of the phosphido PhP–C(dione) bond, and the presence of three edge-bridging hydrides is supported
by 1H NMR spectroscopy. The reaction of 4 with added PPh3 and PMe3 has been investigated; the uptake
of a single phosphine ligand occurs regiospecifically at one of the phosphido-bound ruthenium centers to
give Ru3(CO)6L(l3-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (PPh3, 6; PMe3, 7). Compound 6 contains 48e-
and exhibits a structural motif similar to that found in 4. Compound 7 readily adds a second PMe3 ligand
to yield the bis-substituted cluster Ru3(CO)6(PMe3)2(l2-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (8). The
solid-state structure of 8 confirms the loss of two ruthenium–ruthenium bonds and the conversion of
the original face-capping l3-COMe ligand to a l2-COMe moiety that tethers two non-bonding ruthenium
Received 15 March 2008
Received in revised form 2 April 2008
Accepted 2 April 2008
Available online 10 April 2008
Keywords:
Ruthenium clusters
Ligand substitution
Diphosphine ligand
P–C bond activation
Cluster expansion
centers. The two PMe3 ligands in
8 coordinate to the same ruthenium center, and the
9e- P(Ph)C@C(PPh2)C(O)CH2C(O) ligand binds all three ruthenium atoms through the phosphine, phosph-
ido, alkene, and carbonyl moieties. Near-UV irradiation of 8 leads to loss of CO and polyhedral contraction
of the triruthenium frame to yield the 48e- cluster Ru3(CO)5(PMe3)2(l3-COMe)[l-P(Ph)C@
C(PPh2)C(O)CH2C(O)] (9).
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
phino)maleic anhydride (bma) gives the chelated cluster HRu3
(CO)8(bma)(l-COMe) and the diphenylphosphine-substituted clus-
Activation of the methylidyne-bridged cluster HRu3(CO)10
(l-COMe) (1) by the oxidative-decarbonylation reagent Me3NO in
the presence of the rigid diphosphine ligand 2,3-bis(diphenylphos-
ter HRu3(CO)8(Ph2PH)[l-PPh2C@CC(O)OC(O)] as the major and
minor products, respectively [1]. Eq. (1) summarizes the reaction
between 1 and the bma ligand. Controlled thermolysis of 1 with
bma yields only trace amounts of HRu3(CO)8(bma)(l-COMe) due
to its facile decomposition under the reaction conditions. Also
exacerbating the situation is the extensive loss of all bma-substi-
tuted products during chromatographic work-up due to the delete-
rious support-induced hydrolysis of the anhydride ring [2].
* Corresponding authors. Tel.: +1 713 743 2771 (S.G. Bott); tel.: +1 940 565 3548
(M.G. Richmond).
E-mail addresses: sbott@uh.edu (S.G. Bott), cobalt@unt.edu (M.G. Richmond).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.04.007

2328
S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
OMe
Ru
O
O
OMe
O
Ru
H
Ru
Ru
H
Ru
Ru
Ru
Ph2HP
PPh2
H
ð1Þ
Me3NO
PPh2
Ru
Ru
O
Ph2P
O
O
O
O
O
major
minor
Ph2P
PPh2
bma
Since a detailed mechanistic study on the degradation path-
way(s) exhibited by the bma-chelated cluster HRu3(CO)8(bma)(l-
COMe) during thermolysis and was hampered, in part, due to the
unavoidable decomposition of the bma-derived products during
chromatographic separation, the reaction between 1 and the re-
lated diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopen-
ten-1,3-dione (bpcd) was next explored. While both ligands are
structurally similar in terms of the their cluster binding properties,
the dione moiety associated with the bpcd ligand is stable to chro-
matographic supports. Treatment of 1 with bpcd in the presence of
Me3NO furnishes the bpcd-chelated cluster HRu3(CO)8(bpcd)
(l-COMe) (2), which unlike its bma counterpart HRu3(CO)8(b-
ma)(l-COMe), is easily purified by column chromatography and
isolated in high yields. The ready availability of 2 has greatly facil-
itated our investigation on the reactivity of the ancillary methyli-
dyne and bpcd ligands in this and other related clusters under
thermal and photochemical activation. Previous reports from our
groups have demonstrated low-energy manifolds for the activation
of the diphosphine ligands bma and bpcd in a variety of polynu-
clear systems containing face-capping carbyne and alkyne ligands
[3].
for cluster 9 were collected at the UNT mass spectrometry facility
in the positive ion mode, using a MeOH matrix containing 1%
AcOH. The spectroscopic data for clusters 2–9 are summarized in
Table 1.
2.2. Reaction of HRu3(CO)10(l-COMe) with bpcd in the presence
of Me3NO to give HRu3(CO)8(l-COMe)(bpcd) (2) and
HRu3(CO)8(Ph2PH)[l-PPh2C@CC(O)CH2C(O)] (3)
To 0.35 g (0.52 mmol) of 1 and 0.27 g (0.58 mmol) of bpcd in a
large Schlenk flask under argon was added 50 mL of CH2Cl2 by can-
nula. The solution was stirred at room temperature for 1 h and
then examined by both TLC and IR spectroscopy. Only the two
reactants were observed, at which point 84 mg (1.1 mmol) of
Me3NO was next added, causing an immediate change in the color
of the solution from red to yellow-brown. Stirring was continued
for an additional 0.5 h and the solution was examined by TLC,
which revealed the presence of one major yellow-brown spot cor-
responding to 2 (Rf = 0.25 using 1:1 CH2Cl2/hexane), in addition to
a trace amount of 1 (Rf = 0.90 same eluent) and red-black material
at the origin of the plate. After the solvent was removed under vac-
uum, the residue was purified by column chromatography over sil-
ica using hexane to first elute unreacted 1, after which the mobile
phase was changed to CH2Cl2 to furnish 2. Washing the column
with acetone allowed for the separation of a small amount of the
red 3. Both new products were recrystallized from benzene/hexane
at room temperature to yield 0.46 g (82%) of 2 and 15 mg (2.9%) of
3. Compound 2: Anal. Calc. for C39H26O11P2Ru3 ꢀ 1/4C6H6: C, 46.05;
H, 2.61. Found: C, 45.89; H, 2.85%. Compound 3: Anal. Calc. for
2. Experimental
2.1. General
The carbonylation of RuCl3 ꢀ xH2O to give Ru3(CO)12 was con-
ducted in a 1000 mL Parr Series 4000 rocking autoclave and em-
ployed the procedure of Bruce [4], while the starting cluster 1
was prepared according to the procedure of Keister et al. [5]. The
bpcd ligand used in this study was synthesized from 4,5-di-
chloro-4-cyclopenten-1,3-dione and Ph2PSiMe3 [6]. All reaction
solvents were distilled from an appropriate drying agent under ar-
gon using Schlenk techniques and stored in Schlenk storage vessels
equipped with high-vacuum Teflon stopcocks [7]. The IR and NMR
solvents were reagent grade and were typically degassed by three
pump-thaw-degas cycles prior to their use. The reported combus-
tion analyses were performed by Atlantic Microlab, Norcross, GA.
The infrared spectra were recorded on a Nicolet 20 SXB FT-IR
spectrometer in a 0.1 mm NaCl cell, using PC control and OMNIC
software. The reported 1H and 31P NMR spectra were recorded at
200 MHz on a Varian Gemini-200 spectrometer and 121 MHz on
a Varian 300-VXR spectrometer, respectively. The reported 31P
chemical shifts, which were recorded in the proton-decoupled
mode unless otherwise stated, are referenced to external H3PO4
(85%), taken to have d = 0. The reported ESI mass spectral data
C
37H24O10P2Ru3 ꢀ 1/2C6H6: C, 46.48; H, 2.61. Found: C, 46.34; H,
2.69%.
2.3. Thermolysis of HRu3(CO)8(l2-COMe)(bpcd) (2) to Ru3(CO)7
(l3-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (4)
To a Schlenk tube was charged 0.20 g (0.19 mmol) of 2 under
argon flush, followed by 30 mL of 1,2-dichloroethane (DCE). The
vessel was sealed and heated at ca. 80–90 °C for period of 2 h, with
the solution slowly turning from yellow-brown to red in color.
Upon cooling, TLC analysis using a 10:1 mixture of CH2Cl2/acetone
as the eluent revealed trace amounts of 1 (Rf = 0.95) and 2
(Rf = 0.60), along with
a large red spot corresponding to 4
(Rf = 0.25) and some black material at the origin. The solvent was
removed and 4 subsequently isolated by column chromatography
using the aforementioned eluent. The desired product was recrys-

S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
2329
Table 1
IR and NMR spectroscopic data for the triruthenium clusters 2–9
Cluster
IRa (cmꢁ1
)
31P NMR, db
1H NMR, d
2
2074 (s), 2037 (vs), 2000 (s), 1982 (s),
1974 (s), 1946 (w, sh), 1746 (w, sym
dione), 1714 (m, antisym dione)
2079 (s), 2039 (vs), 2027 (vs), 1980 (s),
1712 (m, sym dione), 1682 (m, antisym
dione)
2075 (s), 2020 (vs), 1978 (m), 1968 (m),
1708 (m, sym dione), 1684 (m, antisym
dione)
51.74 (s), 43.62 (s)
7.00–8.20 (m, 20H, aryl), 4.07 (s, 3H, OMe), 3.41 (AB
2
quartet, 2H, CH2, JH–H = 22 Hz), ꢁ13.29 (t, 1H, hydride,
2JP–H = 7 Hz)
1
3
4
5
32.28 [s, Ph2P(dione)], 7.70 (s, Ph2PH)
6.83–7.80 (m, 20H, aryl), 6.89 (d, 1H, Ph2PH, JP–
H = 388 Hz), 3.01 (AB quartet, 2H, CH2, JH–H = 22 Hz),
2
2
ꢁ13.34 (dd, 1H, hydride, JP–H = 12, 18 Hz)
2
83.15 (d, l2-phosphido, JP–P = 9 Hz), 37.15 (d,
7.20–7.84 (m,15H, aryl), 4.54 (s, 3H, OMe), 3.51 (AB
2
2
phosphine, JP–P = 9 Hz)
quartet, 2H, CH2, JH–H = 22 Hz)
2101 (s), 2041 (vs), 1933 (s), 1722 (w,
sym dione), 1689 (m, antisym dione)
259.32 (s, l3-phosphido), 18.17 (s, phosphine)
7.05–7.80 (m, 15H, aryl), 2.95 (s, 2H, CH2), ꢁ17.41 (br t,
1H, hydride, J = 15 Hz), ꢁ18.25 (br d, 1H, hydride,
J = 15 Hz), ꢁ18.70 (br m, 1H, hydride)
6
7
2027 (m), 2000 (vs), 1966 (s), 1707 (m,
sym dione), 1681 (m, antisym dione)
2032 (m), 2002 (vs), 1968 (m), 1944 (sh),
1693 (m, sym dione), 1670 (m, antisym
dione)
85.01 (dd, l2-phosphido, JP–P = 156, 7 Hz), 42.21 (d,
PPh3, JP–P = 156 Hz), 41.08 (d, phosphine, JP–P = 7 Hz)
80.95 (dd, l2-phosphido, JP–P = 19, 15 Hz), 39.22 (dd,
phosphine, JP–P = 32, 15 Hz), ꢁ10.40 (dd, PMe3,
JP– P = 32, 19 Hz)
7.10–7.90 (m, 30H, aryl), 3.45 (AB quartet, 2H, CH2,
2JH–H = 21 Hz), 3.02 (s, 3H, OMe)
7.05–7.95(m, 15H, aryl), 4.56 (s, 3H, OMe), 3.53 (AB
2
quartet, 2H, CH2, JH–H = 21 Hz), 1.64 (d, 9H, PMe3,
2JP–H = 10 Hz)
8
9
2051 (vs), 1994 (s), 1975 (s), 1942 (m),
1906 (m), 1637 (m, free dione CO)
27.93 (d, phosphine, JP–P = 22 Hz), 2.12 (dd, PMe3,
JP–P = 244, 22 Hz), ꢁ12.27 (t, PMe3, JP–P = 22 Hz),
ꢁ52.15 (dt, l2-phosphido, JP–P = 244, 22 Hz)
73.72 (m, l2-phosphido), 48.50 (m, phosphine), 7.80
(m, PMe3), ꢁ9.45 (t, PMe3, J = 33 Hz)
6.48–7.70 (m, 15H, aryl), 4.42 (s, 3H, OMe), 4.20 (AB
2
quartet, 2H, CH2, JH–H = 21 Hz), 1.31 (d, 9H, PMe3,
2
2JP–H = 10 Hz), 0.84 (d, 9H, PMe3, JP–H = 10 Hz)
2065 (w), 2010 (vs), 1984 (vs), 1951 (vs),
1908 (s), 1675 (m, sym dione), 1650 (m,
antisym dione)
6.94–7.84 (m, 15H, aryl), 4.50 (s, 3H, OMe), 3.50 (AB
2
quartet, 2H, CH2, JH–H = 21 Hz), 1.53 (d, 9H, PMe3,
2
2JP–H = 10 Hz), 1.18 (d, 9H, PMe3, JP–H = 10 Hz)
a
All IR spectra were recorded in CH2Cl2.
All NMR data were recorded in CDCl3 at room temperature.
b
tallized from CH2Cl2/hexane to afford 0.15 g (84% yield) of 4. Anal.
Calc. for C32H20O10P2Ru3: C, 41.34; H, 2.17. Found: C, 41.16; H,
2.12%.
Calc. for C39H35O9P3Ru3 ꢀ CH2Cl2 ꢀ MeOH: C, 47.82; H, 3.23. Found:
C, 47.43; H, 2.97%.
2.6. Reaction of Ru3(CO)7(l3-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)]
(4) with PMe3 to give Ru3(CO)6(PMe3)(l3-COMe)
[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (7) and Ru3(CO)6(PMe3)2
(l2-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (8)
2.4. Synthesis of H3Ru3(CO)7(l3-PPh)[l-C@C(PPh2)C(O)CH2C(O)] (5)
from the thermolysis of Ru3(CO)7(l3-COMe)
[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (4) in the presence of hydrogen
To a Fisher-Porter tube was added 0.12 g (0.13 mmol) of 2 and
50 mL of toluene, after which the vessel was sealed and degassed
via three pressurization cycles using nitrogen. The vessel was next
charged with 100 psi of H2 and stirred at room temperature for
several hours and examined by TLC, which confirmed the presence
of only starting cluster. The solution was then heated at ca.
60–70 °C overnight in a thermostated oil bath. Upon cooling, the
solution was again examined by TLC using CH2Cl2 as the eluent,
revealing the complete consumption of 2 and the presence of a yel-
low spot (Rf = 0.45) corresponding to 5. Chromatographic separa-
tion, followed by recrystallization from CH2Cl2/MeOH at 0 °C,
furnished 60 mg (52% yield) of 5. Anal. Calc. for C30H20O9P2Ru3:
C, 40.45; H, 2.25. Found: C, 40.53; H, 2.32%.
0.17 g (0.18 mmol) of 4 and 30 mL CH2Cl2 were charged to a
Schlenk tube and the contents cooled to ꢁ78 °C using an external
dry ice/acetone bath. 0.50 mL of 0.47 M PMe3 in THF (0.24 mmol)
was next added and the vessel sealed to protect against the loss
of the volatile PMe3, with stirring continued with warming to
room temperature. The initial red color of the solution slowly
turned dark red as the reaction approached room temperature.
Stirring was continued for an additional 4 h once room tempera-
ture had been reached and the solution examined by TLC. Com-
pound
4 was completely consumed and two new spots
corresponding to the PMe3-substituted clusters 7 (Rf = 0.85) and
8 (Rf = 0.25) were observed by TLC using an eluent composed of
5:1 CH2Cl2/Et2O. Both products were isolated by flash column
chromatography using the same solvent system as employed in
the TLC. Recrystallization of 7 from benzene/MeOH furnished 7
in 80% yield (0.14 g), while the combustion sample and X-ray
quality crystals of 8 were obtained from a recrystallization using
CH2Cl2/benzene. Yield of 8: 26 mg (14% yield). The yield of 8 is
greatly increased by using a threefold excess of PMe3 relative to
4 or by treating 7 (isolated or in situ) with additional PMe3. Com-
pound 7: Anal. Calc. for C34H29O9P3Ru3 ꢀ 1/2C6H6: C, 43.71; H,
3.17. Found: C, 44.17; H, 3.35%. Compound 8: Anal. Calc. for
2.5. Synthesis of Ru3(CO)6(PPh3)(l3-COMe)
[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (6) from the reaction of
Ru3(CO)7(l3-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (4) with PPh3
The substitution reaction was carried out in medium-sized
Schlenk tube under argon using 0.10 g (0.11 mmol) of 4 and
30 mg (0.11 mmol) of PPh3 in 40 mL of CH2Cl2. The reactants were
refluxed for ca. 2 h at room temperature and the extent of the reac-
tion checked by TLC analysis. Other than some unreacted 4 and a
trace amount of PPh3, the presence of a red-brown spot corre-
sponding to 6 was observed at Rf = 0.40 using 1:1 CH2Cl2/petro-
leum ether as the mobile phase. Compound 6 was isolated by
column chromatography by first eluting with hexane to remove
unreacted starting materials and then an eluent composed of a
10:1 mixture of CH2Cl2/Et2O. Recrystallization of 6 from CH2Cl2
and MeOH afforded the analytical sample and single crystals suit-
able for X-ray diffraction analysis. Yield of 6: 72% (90 mg). Anal.
C
37H38O9P4Ru3 ꢀ CH2Cl2: C, 40.08; H, 3.54. Found: C, 40.29; H,
3.48%.
2.7. Photochemical conversion of Ru3(CO)6(PMe3)2(l-COMe)
[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (8) to 7 and Ru3(CO)5(PMe3)2
(l3-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (9)
A 0.15 g (0.14 mmol) sample of 8 was dissolved in ca. 25 mL of
CH2Cl2 and irradiated between two GE Blacklight bulbs overnight.

2330
S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
Table 2
X-ray crystallographic data and processing parameters for 4–6, 8, and 9
Compound
4
5
6
8
9
CCDC Entry No.
Crystal system
Space group
617376
Triclinic
P1
617374
Triclinc
P1
617375
Monoclinic
P21/n
617377
Triclinic
P1
617378
Monoclinic
P21/n
ꢀ
ꢀ
ꢀ
a (Å)
b (Å)
c (Å)
a (°)
10.8594(7)
11.933(1)
13.420(1)
86.983(8)
88.562(6)
75.961(8)
1685.1(3)
9.857(1)
10.5766(8)
17.594(2)
102.186(9)
105.19(1)
92.887(8)
1719.4(3)
C30H20O9P2Ru3 ꢀ 1/2C7H8
932.65
20.084(1)
12.7078(9)
22.029(2)
12.1735(7)
13.1955(7)
15.6289(8)
113.616(4)
93.533(5)
89.956(5)
2295.2(2)
C37H38O9P4Ru3 ꢀ CH2Cl2
1138.75
11.929(1)
13.399(1)
28.775(2)
b (°)
116.906(6)
95.67(2)
c (°)
V (Å3)
5013.7(7)
4577(2)
C36H38O8P4Ru3 ꢀ THF
1097.91
4
1.593
0.71073
11.44
Molecular formula
Fw
C
32H20O10P2Ru3
C49H35O9P3Ru3 ꢀ MeOH ꢀ CH2Cl2
929.67
2
1.832
0.71073
14.49
n/a
1280.93
4
Formula units per cell (Z)
Dcalc. (g/cm3)
k (Mo Ka), Å
Absorption coefficient (cmꢁ1
Rmerge
2
2
1.801
0.71073
14.19
n/a
1.697
0.71073
11.33
1.648
0.71073
12.58
n/a
)
0.018
0.031
Abs. corr. factor
Total reflections
Independent reflections
Data/res/parameters
R
0.79/1.14
4166
3746
3746/0/334
0.0318
0.87/1.11
4221
2104
2104/0/263
0.0467
0.92/1.07
6470
4657
4657/0/442
0.0420
0.85/1.13
5594
4732
4732/0/506
0.0315
0.63/1.23
3474
966
966/0/225
0.0567
Rw
0.0347
1.82
0.0726
0.95
0.0444
1.09
0.0350
1.10
0.0661
0.91
GOF on F2
Weights
[0.04F2 + (rF)2]ꢁ1
0.74 near Ru(1)
[0.04F2 + (rF)2]ꢁ1
0.88 near Ru(1), ꢁ0.24
[0.04F2 + (rF)2]ꢁ1
0.92 near CH2Cl2
[0.04F2 + (rF)2]ꢁ1
1.0 near CH2Cl2, ꢁ0.77
[0.04F2 + (rF)2]ꢁ1
0.76 near THF
Dq(max), Dq(min) (e/Å3)
TLC examination of the solution the following day using CH2Cl2 as
the eluent revealed the presence of 7 (major; Rf = 0.25) and a new
spot (minor; Rf = 0.15), whose identity was later established as 9.
Both products were isolated by chromatographic separation,
affording 86 mg of 7 (62%) and 15 mg (10%) of 9. ESI-MS m/z:
1025.73 for [9+H]+.
inside a Lindemann capillary tube, followed by mounting on an En-
raf-Nonius CAD-4 diffractometer. After the cell constants were ob-
tained, intensity data in the range of 2° 6 2h 6 44° were collected
at 298 K and were corrected for Lorentz, polarization, and absorp-
tion (DIFABS). The structure for 4 was solved by SIR, and all non-
hydrogen atoms were located with difference Fourier maps and
full-matrix least-squares refinement. With the exception of the
phenyl carbon atoms, all non-hydrogen atoms were refined aniso-
tropically. The remaining four structures were all solved by using
SHELX-86 and all non-hydrogen atoms were located with difference
Fourier maps and full-matrix least-squares refinement. For
5 ꢀ 1/2C7H8, the three bridging were not located during refinement,
and all of the non-hydrogens were refined anisotropically except
for the carbon atoms. In the case of 6 ꢀ CH2Cl2 ꢀ MeOH, all of the
non-hydrogen atoms except for the phenyl carbons were refined
anisotropically, while all of the non-hydrogen atoms were refined
anisotropically for 8 ꢀ CH2Cl2. All of the non-hydrogen atoms in
9 ꢀ THF had to be refined isotropically due to solvent loss and the
poor quality of the crystal. The carbon-bound hydrogen atoms in
all five cluster compounds were assigned to calculated positions
and allowed to ride on the attached heavy atom. Table 2 summa-
rizes the X-ray processing and data collection parameters, and
Table 3 displays selected bond distances and angles for these
clusters.
2.8. Kinetics studies on the conversion of 2 to 4
The UV–Vis studies were carried out using a cluster concentra-
tion of ca. 10ꢁ4 M employing 1.0 cm quartz UV–Vis cells that were
equipped with a high-vacuum Teflon stopcock to facilitate han-
dling on the vacuum line. Solutions of 2 were prepared under ar-
gon and used immediately before each kinetic measurement. The
Hewlett–Packard 8452A diode array spectrometer employed in
our studies was configured with a variable-temperature cell holder
and was connected to a VWR constant temperature circulator,
allowing for the quoted temperatures to be maintained within
0.5 K. The UV–Vis kinetics were monitored by following the de-
crease of the 420 nm absorbance band as a function of time for
at least 4 half-lifes. The rate constants quoted in Table 4 were
determined by non-linear regression analysis using the single
exponential function [8]:
AðtÞ ¼ A1 þ DA ꢂ eðꢁktÞ
The activation parameters for the conversion of 2 to 4 were cal-
culated from a plot of ln(k/T) versus Tꢁ1 [9], with the error limits
representing the deviation of the data points about the least-
squares line of the Eyring plot.
3. Discussion
3.1. Synthesis and spectroscopic data for 2 and 3
The reaction between HRu3(CO)10(l-COMe) (1) and the diphos-
phine ligand bpcd proceeds readily in CH2Cl2 at room temperature
in the presence of the oxidative-decarbonylation reagent Me3NO
(2 equiv.) [10]. TLC analysis of the reaction solution using a 1:1
mixture of CH2Cl2/hexane confirmed the near quantitative con-
sumption of cluster 1 and bpcd and the presence of one major spe-
cies (Rf = 0.25), whose identity was subsequently confirmed as
HRu3(CO)8(l-COMe)(bpcd) (2). The red-black material that re-
mained at the origin of the TLC plate was also investigated by rede-
veloping the TLC plate using acetone as an eluent. The more polar
solvent afforded a second spot that was ascribed to the phosphido-
2.9. X-ray diffraction structures for 4–6, 8, and 9
Single crystals of 4 suitable for X-ray crystallography were
grown from a CH2Cl2 solution containing 4 that had been layered
with hexane, with crystals of 5 ꢀ 1/2 toluene, grown from a toluene
solution of 5 that had layered with hexane. The growth of X-ray
quality crystals of 6 ꢀ CH2Cl2 ꢀ MeOH has already been described,
while the crystals of 8 ꢀ CH2Cl2 and 9 ꢀ THF were grown from clus-
ter solutions in CH2Cl2 and THF, respectively, that had been layered
with hexane. In each case, a suitable crystal was chosen and sealed

S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
2331
Table 3
Selected bond distances (Å) and angles (degr) for 4–6, 8, and 9a
Cluster 4
Bond distances
Ru(1)–Ru(2)
Ru(2)–Ru(3)
Ru(1)–P(2)
Ru(2)–P(2)
Ru(3)–C(11)
Ru(3)–C(16)
C(11)–C(15)
C(13)–C(14)
2.8317(7)
Ru(1)–Ru(3)
Ru(1)–P(1)
2.7517(7)
2.334(2)
2.126(7)
2.179(6)
2.230(6)
1.489(8)
1.529(8)
1.464(8)
2.8583(6)
2.337(2)
2.325(2)
2.228(6)
1.950(6)
1.439(7)
1.518(7)
Ru(1)–C(16)
Ru(2)–C(16)
Ru(3)–C(15)
C(11)–C(12)
C(12)–C(13)
C(14)–C(15)
Bond angles
P(1)–Ru(1)–P(2)
P(2)–Ru(1)–C(16)
C(11)–Ru(3)–C(15)
Ru(3)–C(11)–P(1)
Ru(3)–C(15)–C(11)
83.22(5)
90.9(2)
37.6(2)
95.1(2)
71.1(3)
P(1)–Ru(1)–C(16)
P(2)–Ru(2)–C(16)
C(16)–O(17)–C(18)
Ru(3)–C(15)–P(2)
Ru(1)–C(16)–Ru(2)
110.9(2)
89.9(2)
118.2(5)
86.3(2)
82.3(2)
Cluster 5
Bond distances
Ru(1)–Ru(2)
Ru(2)–Ru(3)
Ru(1)–P(2)
Ru(2)–C(15)
C(11)–C(15)
C(13)–C(14)
2.926(3)
2.972(2)
2.304(6)
2.06(2)
1.39(3)
1.51(3)
Ru(1)–Ru(3)
Ru(1)–P(1)
Ru(2)–P(2)
Ru(3)–P(2)
C(12)–C(13)
C(14)–C(15)
2.960(2)
2.336(6)
2.290(6)
2.323(6)
1.52(3)
1.47(3)
Bond angles
P(1)–Ru(1)–P(2)
Ru(1)–P(1)–C(11)
Ru(1)–P(2)–Ru(3)
P(1)–C(11)–C(15)
90.8(2)
110.6(7)
79.5(2)
125(1)
P(2)–Ru(2)–C(15)
Ru(1)–P(2)–Ru(2)
Ru(2)–P(2)–Ru(3)
Ru(2)–C(15)–C(11)
96.3(6)
79.1(2)
80.2(2)
127(1)
Cluster 6
Bond distances
Ru(1)–Ru(2)
Ru(2)–Ru(3)
Ru(1)–P(2)
Ru(2)–C(11)
Ru(2)–C(16)
Ru(3)–P(3)
O(17)–C(16)
C(11)–C(12)
C(12)–C(13)
C(14)–C(15)
2.785(1)
2.8195(7)
2.328(2)
2.214(7)
1.985(8)
2.413(2)
1.33(1)
1.49(1)
1.52(1)
1.49(1)
Ru(1)–Ru(3)
Ru(1)–P(1)
Ru(1)–C(16)
Ru(2)–C(15)
Ru(3)–P(2)
Ru(3)–C(16)
O(17)–C(18)
C(11)–C(15)
C(13)–C(14)
2.8728(8)
2.308(2)
2.215(8)
2.246(8)
2.340(2)
2.097(7)
1.434(9)
1.445(9)
1.503(9)
Bond angles
P(1)–Ru(1)–P(2)
P(1)–Ru(1)–C(2)
P(2)–Ru(1)–C(1)
P(2)–Ru(1)–C(16)
C(3)–Ru(2)–C(15)
C(11)–Ru(2)–C(16)
P(2)–Ru(3)–P(3)
P(3)–Ru(3)–C(16)
C(6)–Ru(3)–C(16)
Ru(1)–C(16)–Ru(2)
Ru(2)–C(16)–Ru(3)
84.30(7)
101.9(2)
95.5(3)
P(1)–Ru(1)–C(1)
P(1)–Ru(1)–C(16)
P(2)–Ru(1)–C(2)
C(3)–Ru(2)–C(11)
C(11)–Ru(2)–C(15)
C(15)–Ru(2)–C(16)
P(2)–Ru(3)–C(16)
C(5)–Ru(3)–C(16)
Ru(2)–C(15)–P(2)
Ru(1)–C(16)–Ru(3)
103.3(2)
111.0(2)
171.8(3)
97.5(3)
37.8(2)
122.2(3)
91.9(2)
125.2(4)
86.2(3)
83.5(3)
89.3(2)
132.0(3)
129.7(3)
178.14(6)
86.6(2)
133.2(3)
82.9(3)
87.3(3)
Cluster 8
Bond distances
Ru(1)–Ru(2)
Ru(1)–C(15)
Ru(2)–P(1)
Ru(3)–P(2)
Ru(3)–P(4)
Ru(3)–C(16)
O(14)–C(14)
C(11)–C(15)
C(13)–C(14)
2.8610(6)
2.177(5)
2.411(2)
2.455(1)
2.357(2)
2.098(6)
1.285(7)
1.467(8)
1.526(9)
Ru(1)–C(11)
Ru(1)–C(16)
Ru(2)–P(2)
Ru(3)–P(3)
Ru(3)–O(14)
O(12)–C(12)
C(11)–C(12)
C(12)–C(13)
C(14)–C(15)
2.297(6)
1.998(7)
2.429(1)
2.404(2)
2.181(4)
1.219(8)
1.464(8)
1.549(7)
1.397(6)
Bond angles
C(2)–Ru(1)–C(11)
C(11)–Ru(1)–C(15)
C(15)–Ru(1)–C(16)
P(2)–Ru(3)–P(3)
P(3)–Ru(3)–P(4)
P(2)–Ru(3)–C(16)
P(3)–Ru(3)–C(16)
123.0(3)
38.2(2)
90.3(2)
98.19(5)
95.09(6)
78.2(2)
175.6(1)
C(2)–Ru(1)–C(15)
C(11)–Ru(1)–C(16)
P(1)–Ru(2)–P(2)
P(2)–Ru(3)–P(4)
P(2)–Ru(3)–O(14)
P(3)–Ru(3)–O(14)
P(4)–Ru(3)–O(14)
155.5(2)
128.5(2)
84.35(5)
160.98(7)
85.13(9)
92.1(1)
80.8(1)
(continued on next page)

2332
S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
Table 3 (continued)
P(4)–Ru(3)–C(16)
O(14)–Ru(3)–C(16)
Ru(1)–C(16)–Ru(3)
89.0(1)
90.0(2)
117.7(3)
O(14)–Ru(3)–C(6)
Ru(2)–P(2)–Ru(3)
176.3(2)
125.31(6)
Cluster 9
Bond distances
Ru(1)–Ru(2)
Ru(2)–Ru(3)
Ru(1)–P(2)
Ru(2)–P(2)
Ru(2)–C(16)
Ru(3)–C(11)
Ru(3)–C(16)
C(11)–C(15)
C(13)–C(14)
2.855(5)
2.814(6)
2.37(1)
2.37(1)
2.07(4)
2.24(1)
2.02(4)
1.47(6)
1.44(6)
Ru(1)–Ru(3)
Ru(1)–P(1)
Ru(1)–C(16)
Ru(2)–P(3)
Ru(3)–P(4)
Ru(3)–C(15)
C(11)–C(12)
C(12)–C(13)
C(14)–C(15)
2.756(5)
2.36(1)
2.03(4)
2.35(1)
2.32(1)
2.16(4)
1.57(6)
1.51(5)
1.47(5)
Bond angles
P(1)–Ru(1)–P(2)
P(2)–Ru(1)–C(16)
P(2)–Ru(2)–C(16)
P(4)–Ru(3)–C(16)
C(11)–Ru(3)–C(16)
Ru(1)–P(2)–Ru(2)
P(4)–Ru(3)–C(15)
C(5)–Ru(3)–C(15)
79.9(4)
91(1)
89(1)
P(1)–Ru(1)–C(16)
P(2)–Ru(2)–P(3)
P(3)–Ru(2)–C(16)
C(11)–Ru(3)–C(15)
C(15)–Ru(3)–C(16)
P(4)–Ru(3)–C(11)
C(5)–Ru(3)–C(11)
C(5)–Ru(3)–C(16)
115(1)
93.1(4)
153(1)
39(1)
117(1)
103(1)
110(2)
122(2)
91(1)
127(2)
74.2(4)
141(1)
101(2)
a Numbers in parentheses are estimated standard deviations in the least significant digits.
bridged cluster HRu3(CO)8(Ph2PH)[l-PPh2C@CC(O)CH2C(O)] (3).
The products 2 and 3 were isolated by column chromatography
and characterized by IR and NMR spectroscopies and combustion
analyses. Compounds 2 and 3 are mildly air sensitive in solution,
with those solutions exposed to oxygen exhibiting decomposition
after several hours. The formulated structures for these clusters
are shown below.
and HRu3(CO)8(l2-PPh2)(bpcd), where the diphosphine ligands
are chelated to one of the hydride-bridged ruthenium centers
[1,12,13].
The spectroscopic properties of 3 mirror those data reported by
us for the diphenylphosphine-substituted cluster HRu3-
(CO)8(Ph2PH)[l-PPh2C@CC(O)OC(O)], which was also isolated as a
minor product from the reaction of 1 with bma. The loss of the
bridging methylidyne moiety and the P–C bond activation of the
bma ligand that accompany the formation of HRu3(CO)8
(Ph2PH)[l-PPh2C@CC(O)OC(O)] were unequivocally established
by X-ray diffraction analysis [1]. Unlike HRu3(CO)8(Ph2PH)[l-
PPh2C@CC(O)OC(O)] which exists as a 9:1 mixture of stereoisomers
in solution, 3 exhibits a single set of 31P resonances at d 7.70 and
32.28 for the coordinated Ph2PH and Ph2PC (dione ring) moieties,
respectively.
O
OMe
O
Ru
H
Ru
Ru
Ru
Ph2HP
PPh2
H
PPh2
Ru
The thermolysis of 1 with added bpcd was also investigated in
1,2-dichloroethane at ca. 80–90 °C as an alternative route to 2.
Heating an equimolar amount of 1 and bpcd does indeed afford
2, as verified by TLC monitoring of the reaction solution, in addition
to a new red cluster that was later shown to be Ru3(CO)7(l3-CO-
Me)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (4) (vide infra). Independent
thermolysis reactions employing 2 were also performed and these
reactions confirmed that the thermolysis of 2 does indeed produce
4. These experiments indicate that the synthesis of 2 via the direct
thermolysis of 1 with bpcd is not a viable synthetic route to 2 be-
cause the initially formed product is not stable and competitively
transforms to 4.
Ru
O
Ph2P
O
2
3
The IR spectrum of 2 shows terminal carbonyl bands at 2074 (s),
2037 (vs), 2000 (s), 1982 (s), 1974 (s), and 1946 (w, sh) cmꢁ1, in
addition to two lower energy m(CO) bands at 1746 and 1714
cmꢁ1 associated with the vibrationally coupled symmetric and
antisymmetric dione carbonyl groups belonging to the platform
ring of the bpcd ligand [11]. The terminal m(CO) bands for 2 are
in excellent agreement with those data reported earlier by us for
the related bma-substituted cluster HRu3(CO)8(l-COMe)(bma)
[1]. The 1H NMR spectrum exhibited characteristic resonances at
d ꢁ13.29, 3.41, and 4.07 that are readily assigned to the high-field
hydride, methylene moiety of the bpcd ring, and bridging methoxy
group. The overlapping aryl hydrogens were observed from d 7.00–
8.20. The chelation of the ancillary bpcd ligand in 2 was corrobo-
rated by the observation of two down-field 31P singlets at d 51.74
and 43.62 in the 31P NMR spectrum. The presence of inequivalent
31P resonances is consistent with the formulated structure for 2,
and is in keeping with those data reported in the triruthenium
clusters HRu3(CO)8(l-COMe)(bma), HRu3(CO)8(l2-NCPh2)(bpcd),
3.2. Synthesis, kinetics, and crystallographic data for 4
Heating cluster 2 in either toluene or 1,2-dichloroethane leads
to the rapid loss of CO and benzene and the formation of the phos-
phido-bridged cluster Ru3(CO)7(l3-COMe)[l-P(Ph)C@C(PPh2)C(O)-
CH2C(O)] (4). The formation of benzene was verified by GC–MS
analysis. Compound 4 was observed as the predominant product,
in addition to trace amounts of 1 (<1%), when preparative thermol-
ysis reactions employing 2 were monitored by TLC. Compound 4
was readily isolated by column chromatography and characterized
by NMR and IR spectroscopies and X-ray diffraction analysis. The
thermolysis reaction of 2 to 4 is depicted in Eq. (2). Compound 4
displays terminal m(CO) bands at 2075 (s), 2020 (vs), 1978 (m),

S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
2333
and 1968 (m) cmꢁ1, and the carbonyl bands belonging to dione
moiety appear at 1708 (m) and 1682 (m) cmꢁ1. The shift to lower
energy exhibited by these latter two m(CO) bands relative to the
dione m(CO) bands in 2 indicates that the p bond of the cyclopen-
ten-1,3-dione ring is coordinated to one of the ruthenium centers
[14]. The 1H NMR spectrum exhibits three sets of resonances at d
7.20–7.84, 4.54, and 3.51 in a 15:3:2 integral ratio, respectively,
whose assignments for three aryl rings, a bridging methylidyne
moiety, and a bpcd-derived methylene group are consistent with
the formulated structure for 4. The two 31P doublets recorded in
the 31P NMR spectrum at d 83.15 and 37.15 are congruent with
the presence of proximally situated phosphido and phosphine moi-
eties, respectively, as found by us in other trimetallic clusters con-
taining an activated bpcd ligand [13,15]. The ORTEP diagram of 4 is
shown in Fig. 1, where the loss of one aryl ring is immediately ver-
ified. Compound 4 contains 48-valence electrons, and the triangu-
lar array of ruthenium atoms is face-capped by bridging
methoxymethylidyne and P(Ph)C@CC(O)CH2C(O)PPh2 ligands,
which serve as 3e- and 7e- donor ligands, respectively. The bond
distances and angles associated with the latter ligand are in agree-
ment with those values reported by us in related cluster systems
containing the same ligand [13,15]. The seven ancillary CO groups
are all linear and display bond distances and angles within accept-
able limits.
well-behaved and not subject to gross material loss. The nature
of the solvent is not terribly important, as entries 2 and 3 in Table
4 exhibit nearly identical rate constants for reactions conducted in
toluene and DCE. The effect of added CO on the reaction was also
examined, and these data are seen in entries 5 and 6, where 1
atm of CO retards to the rate by a factor of ca. 102. On the basis
of the first-order kinetics, CO inhibition, and the Eyring activation
parameters [DHà = 30.8(3) kcal/mol; D Sà = 19.6(8) eu], a mecha-
nism involving a rate-limiting, unimolecular CO loss from 2 is sup-
ported [16]. The oxidative Ph–P bond cleavage experienced by the
bpcd ligand and the elimination of benzene that accompany the
formation of 4 must follow after the putative unsaturated species
HRu3(CO)7(l-COMe)(bpcd) has formed in the rate-limiting step of
the reaction.
3.3. Ligand substitution properties of 4
The reactivity of 4 was next explored as part of our interest on
the lability of the face-capping ligand P(Ph)C@CC(O)CH2C(O)PPh2
in associative ligand exchange processes where the p-bound alkene
moiety serves as a coordinatively flexible ligand [17]. Scheme 1
illustrates the various reactions examined. Compound 4 reacts
with H2 (100 psi) at ca. 65 °C in toluene to furnish the phosphinid-
ene-capped 5. The 1H NMR spectrum of 5 exhibits three distinct
hydride resonances at d ꢁ17.41, ꢁ18.25, and ꢁ18.70 in agreement
with a structure containing three hydride-bridged Ru–Ru bonds.
The 15 aromatic hydrogens belonging to the three phenyl groups
appear as a set of overlapping resonances from d 7.05–7.80 while
the methylene hydrogens of the carbocyclic dione ring appear as
a singlet at d 2.95. The two 31P resonances recorded at d 259.32
and 18.17 may be confidently assigned to the face-capping phos-
phinidene and phosphine ligands, respectively. The molecular
structure of 5, which is depicted in Fig. 2, confirms the loss of
the methoxymethylidyne ligand and the cleavage of the PhP–
C(dione) bond belonging to the face-capping P(Ph)C@CC(O)CH2-
C(O)PPh2 ligand in 4. Activation of the latter ligand leads to the ob-
served l3-PPh phosphinidene moiety and the edge-bridging
C@CC(O)CH2C(O)PPh2 ligand in 5. Compound 5 is electron precise
with 48-valence electrons and displays an average Ru–Ru bond
distance of 2.953 Å, whose value is consistent with Ru–Ru bond
distances found in other polynuclear ruthenium clusters [18]. Each
Ru–Ru vector contains an edge-bridged hydride that lies below the
metallic plane capped by the l3-PPh group similar to those pseudo-
axial hydride ligands in the triruthenium clusters H2Ru3(CO)8
(PMePh2)(l3-PPh) and H2Ru3(CO)9(l3-PPh) [19]. The 3e- ligand
C@CC(O)CH2C(O)PPh2 spans the Ru(1)–Ru(2) vector in a plane
roughly parallel to the triangular array of ruthenium atoms and
exhibits a Ru(2)–C(15) r bond of 2.06(2) Å and a Ru(1)–P(1) dative
bond of 2.336(6) Å, whose distances are similar to those distances
O
Ph
O
OMe
P
heat
-CO
-C6H6
Ru
H
Ru
Ru
Ru
PPh2
PPh2
Ru
Ru
MeO
O
Ph2P
O
2
4
ð2Þ
The kinetics for the conversion of 2 to 4 were also investigated
by UV–Vis spectroscopy over the temperature range of 320–343 K.
Here the reaction rates were readily measured by following the de-
crease in the absorbance of the 420 nm band of 2, with the rate
constants presented in Table 4. The observed isosbestic points at
323, 400, and 464 nm confirm that the reaction is kinetically
Table 4
Experimental rate constants for the conversion of 2 to 4a
Entry No.
Temperature (K)
Solvent
104k (sꢁ1)
1
2
3
4
5
6
7
8
320.2
320.2
320.2
326.5
333.3
333.3
338.2
343.1
Toluene
Toluene
DCE
Toluene
Toluene
Toluene
Toluene
Toluene
1.28 0.01
1.36 0.01b
1.31 0.02
3.68 0.12
8.68 0.04
0.10 0.01c
17.3 0.3
31.7 0.2
a
The UV–Vis kinetic data were collected in the specified solvent using
2.2 ꢃ 10ꢁ4 M solution of cluster 2 by following the decrease in the absorbance of
the 420 nm band.
b
Reaction carried out with a 1.1 ꢃ 10ꢁ4 M solution of cluster 2.
Fig. 1. ORTEP diagram of 4 showing the thermal ellipsoids at the 30% probability
level.
c
Reaction carried out under 1 atm of CO.

2334
S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
Ph
P
O
O
Ru
Ru
PPh2
4
MeO
Ru
100 psi H2
heat
L - room temp
Ph
P
O
Ph
P
O
H
L'
Ru
H
Ru
Ru
H
Ru
PPh2
L
O
Ru
MeO
Ru
P
Ph2
O
6 (L = PPh3; L' = CO)
7 (L' = PMe3; L = CO)
5
additional PMe3
with cluster 7
O
O
OMe
Me3P
PPh2
Ru
Ru
8
Me3P
P
Ru
Ph
hν, -CO
O
Ph
P
O
Me3P
MeO
9
Ru
Ru
PMe3
PPh2
Ru
Scheme 1.
reported by us in the cluster compound Ru3(CO)7[l-C@CC(O)CH2-
C(O)PPh2](l-PPh2)(l3-NPh) [20].
small 7 Hz splitting derives from geminal coupling between the
two phosphorus atoms in the face-capping P(Ph)C@CC(O)CH2-
C(O)PPh2 ligand, and the larger coupling of 156 Hz indicates that
the PPh3 must be oriented trans to the phosphido moiety [21].
The 1H NMR spectrum shows an aromatic multiplet from d 7.10–
7.90 that integrates for 30H, supporting the addition of one PPh3
ligand to 6, in addition to an AB quartet for the diastereotopic
methylene hydrogens that is centered at d 3.45, and a three proton
singlet at d 3.02 for the methoxymethylidyne moiety. The exact lo-
Thermolysis of 4 with PPh3 (1 equiv.) in CH2Cl2 gave the mono-
substituted cluster 6 in high yield. The 31P NMR spectrum of 6 in
CDCl3 at room temperature revealed the presence of a single iso-
mer based on one set of resonances at d 85.01 (dd), 42.21 (d),
and 41.08 (d), where the former resonance is readily assigned to
the phosphido moiety. The phosphido resonance appears as a dou-
blet-of-doublets with disparate splittings of 156 Hz and 7 Hz,. The

S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
2335
1994 (sh) cmꢁ1, and these IR data qualitatively mimic the IR spectral
data from the PPh3-substituted cluster 6. The electron rich PMe3 li-
gand in 7 does not appear to promote a significant shift of the termi-
nal m(CO) bands to lower frequencies relative to 6, a trend commonly
found in other clusters containing different PR3 ligands [22]. The in-
creasedelectrondensityin7vis-á-vis6is clearlymanifestedintheIR
frequencies of the vibrationally coupled symmetric and antisym-
metric m(CO) bands of the dione ring. These m(CO) bands in 7 appear
at 1693 and 1670 cmꢁ1, and are 14 cmꢁ1 and 11 cmꢁ1, respectively,
lowerin energythantheidenticaldione carbonylstretchingbands in
6. That the ancillary P(Ph)C@CC(O)CH2C(O)PPh2 ligand serves as a
suitable repository for excess electron density is supported by elec-
trochemical experiments and MO calculations on related com-
pounds bearing a bpcd ligand, where an accessible low-lying p*
orbital on the dione ring has been shown to function as an energet-
ically accessible electron reservoir [23]. The three 31P NMR reso-
nances observed at d 80.95, 39.22, and ꢁ10.40, all of which appear
as doublets-of-doublets, are assigned to the l-phosphido,
PPh2(dione), and PMe3 ligands, respectively. The magnitudes of the
phosphorus–phosphorus coupling constants provide important in-
sightintothestereochemical dispositionoftheancillaryPMe3 ligand
relative to theclusterpolyhedron. Thesimilarityin theIR spectra of 6
and 7 argues for products that have a common phosphine regio-
chemistry, and this places the PMe3 ligand in 7 at the same ruthe-
nium atom as found in 6. Whereas the 31P NMR and X-ray
diffraction data establish the trans relationship between the PPh3 li-
gand and the bridging phosphido moiety in 6, the JP–P values of 19 Hz
and 15 Hz exhibited by the phosphido group in 7 mandate a basal
PMe3 ligand. Scheme 1 shows the PMe3 ligand at one of the two pos-
sible basal sites, either of which would yield a structure that is con-
sistent with the spectroscopic data.
Fig. 2. ORTEP diagram of 5 ꢀ 1/2C7H8 showing the thermal ellipsoids at the 30%
probability level. The solvent molecule has been omitted for clarity.
The minor product, cluster 8, isolated from the reaction between
4 and PMe3 displayedNMR spectral and combustion data supporting
theformationof a trirutheniumclustercontainingtwoPMe3 ligands.
The origin of 8 was subsequently established through the indepen-
dent reaction of 7 with a slight excess of PMe3, giving 8 in near quan-
titative yield. The IR spectrum of 8 presented an interesting
conundrum since only one m(CO) band was observed for the dione
moiety, and the four 31P resonances recorded at d 27.93, 2.12,
ꢁ12.27, and ꢁ52.15 did little to help establish the identity of 8.
Accordingly, cluster 8 was subjected to X-ray crystallographic anal-
ysis, with Fig. 4 showing the molecular structure of 8, as the CH2Cl2
solvate. Immediately obvious is the gross polyhedral alteration
experienced by 8 relative to the metallic motif displayed by clusters
4and6. Compound8contains52-valenceelectrons, andthisnumber
is four electrons in excess of the electron-precise count of 48e- asso-
ciated with triangular clusters. The cleavage of two of the three ori-
ginal Ru–Ru bonds that defined the triangular array of metal atoms
in 7 is understood within the context of polyhedral skeletal electron
pair (PSEP) theory [24]. The extra 4e- in 8 can be traced to the coor-
dination of a second PMe3 ligand and one of the dione’s carbonyl
groups to the Ru(3) atom. This latter Ru(3) center is formally six-
coordinate and may be viewed as possessing a distorted octahedral
geometry. The Ru(1)–Ru(2) vector exhibits a bond distance of
2.8610(6) Å in agreement with its single-bond designation [25],
while the internuclear distances in excess of 3.50 Å for the
Ru(1)ꢀ ꢀ ꢀRu(3) atoms and 4.30 Å for the Ru(2)ꢀ ꢀ ꢀRu(3) atoms clearly
preclude any direct bonding interactions between these ruthenium
centers. The P(Ph)C@CC(O)CH2C(O)PPh2 ligand in 8 functions as a
9e- donor and binds all three metals via the phosphido moiety
(3e-), tertiary phosphine ligand (2e-), alkene p bond (2e-), and one
dione carbonyl group (2e-). The O(14)–Ru(3) vector that defines
the dative bond formed between the dione C(14)O(14) carbonyl
group and the Ru(3) atom reveals a bond distance of 2.181(4) Å,
whose value closely matches those distances in the other ruthenium
cluster compounds containing an oxygen-coordinated carbonyl li-
Fig. 3. ORTEP diagram of 6 ꢀ CH2Cl2 ꢀ MeOH showing the thermal ellipsoids at the
30% probability level. The solvents molecule have been omitted for clarity.
cus of the PPh3 ligand in 6 was established by X-ray crystallogra-
phy. The molecular structure of 6, as the CH2Cl2 and MeOH sol-
vates, shown in Fig. 3 confirms the formal substitution of CO by
PPh3 in this reaction. The basic polyhedral architecture in 6 resem-
bles that of 4, insomuch that the triangular array of ruthenium
atoms is capped by the 3e- COMe and 7e- P(Ph)C@CC(O)CH2-
C(O)PPh2 donor ligands. The Ru–Ru bond distances range from
2.785(1) Å [Ru(1)–Ru(2)] to 2.8728(8) Å [Ru(1)–Ru(3)], and exhibit
a mean distance of 2.826 Å. The PPh3 ligand is attached to Ru(3)
and is situated cis to the l3-COMe ligand and trans to phosphido
atom P(2). The bond angles of 86.6(2)° for the P(3)–Ru(3)–C(16)
atoms and 178.14(6)° for P(2)–Ru(3)–P(3) atoms are in concert
with the stereochemical assignments of the PPh3 relative to the
face-capping ligands. The remaining bond distances and angles ex-
hibit values typical for such groups and require no comment.
Treatment of 4 in CH2Cl2 at ꢁ78 °C with a slight excess of PMe3,
followed by warming to room temperature, leads to the formation
of two new products, as verified by TLC analysis. The new clusters
were isolated by chromatographic separation over silica gel and
characterized in solution by IR and NMR spectroscopies. The faster
moving product, cluster 7, exhibited spectral data consistent with
the substitution of a CO group by a PMe3 ligand. Compound 7 dis-
plays terminal m(CO) bands at 2032 (m), 2002 (vs), 1968 (m), and

2336
S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
Fig. 4. ORTEP diagrams of 8 ꢀ CH2Cl2 (left) and 9 ꢀ THF (right) showing the thermal ellipsoids at the 30% probability level. All solvent molecules have been omitted for clarity.
gand [26]. While the bond distances for the Ru(1)–C(16)
[1.998(7) Å] and Ru(3)–C(16) [2.098(6) Å] vectors associated with
the bridging methoxymethylidyne moiety are comparable to those
distances in the parent cluster HRu3(CO)10(l-COMe) and other poly-
nuclear ruthenium compounds that contain this ligand [27,28], the
bond angle subtended by the Ru(1)–C(16)–Ru(3) atoms [117.7(3)°]
is understandably larger by ca. 28° as compared to the related
angle(s) in edge-bridged l-COMe and face-bridged l3-COMe
complexes [27,28].
Compound 8 is photosensitive in solution, and irradiation of 8
with 366 nm light yields clusters 7 (major) and 9 (minor) as the
principal products. The ESI mass spectrum of 9 gave a pseudo-
molecular ion at m/z: 1025.73 for [9+H]+ that supported the loss
of only one CO ligand from 8, and the 31P NMR spectrum re-
vealed four resonances at d ꢁ9.45, 7.80, 48.50, and 73.72, fully
consistent with the formulated structure of 9 that is depicted
in Scheme 1. The two highest field resonances represent the
PMe3 ligands, with the remaining resonances attributed to the
face-capping P(Ph)C@CC(O)CH2C(O)PPh2 ligand. The ORTEP dia-
gram of 9, as the THF solvate, is shown in Fig. 4, where the for-
mal loss of one CO group, conversion of the bridging
P(Ph)C@CC(O)CH2C(O)PPh2 ligand from a 9e- to a 7e- donor,
and ring closure of the metallic polyhedron are confirmed. Com-
pound 9 contains 48-valence electrons and is electron precise.
The Ru–Ru bond distances range from 2.756(5) Å [Ru(1)–Ru(3)]
to 2.855(5) Å [Ru(1)–Ru(2)], revealing the presence of an asym-
metric metallic core in 9. The vicinal PMe3 ligands are attached
to the Ru(2) and Ru(3) atoms and exhibit a P(3)–Ru(2)–Ru(3)–
P(4) dihedral angle of ca. 127°. The bond angles for the P(4)–
Ru(3)–C(16) [91(1)°] and P(3)–Ru(2)–C(16) [153(1)°] linkages
indicate that the ancillary PMe3 ligands are situated syn and
anti, respectively, to the face-capping methoxymethylidyne moi-
ety. The five terminal Ru–CO ligands display bond distances and
angles fall within acceptable ranges for such groups, with the
remaining bond distances and angles unremarkable relative to
the other clusters presented here.
The observed structure of 8 facilitates the unequivocal assign-
ment of the four 31P resonances recorded in the NMR spectrum.
2
The large JPꢁP value of 244 Hz is attributed to coupling between
the P(2) and P(4) atoms, based on the nearly linear bond angle of
160.98(7)° found for the P(2)–Ru(3)–P(4) linkage. The assignment
of the high-field 31P resonance at d ꢁ52.15 to the phosphido moi-
ety P(2) is supported by the structural data and is congruent with
the established trend exhibited by such ligands and their ligation
of non-bonding metal centers [29]. The bond angles for the P(1)–
Ru(2)–P(2) [84.35(5)°], P(2)–Ru(3)–P(3) [98.19(5)°], and P(3)–
Ru(3)–P(4) [95.09(6)°] linkages confirm the near orthogonal rela-
tionship that exists between these phosphorus centers, leading to
2
smaller JP–P values between these phosphorus centers. Chemical
shifts arguments and 31P data from other cluster analogues facili-
tate the 31P assignments in 8, as depicted below.
4. Conclusions
O
CO substitution in cluster HRu3(CO)10(l-COMe) by the diphos-
phine ligand bpcd gives the bpcd-chelated cluster HRu3-
(CO)8(bpcd)(l-COMe) (2) as the principal reaction product. Facile
loss of benzene occurs on mild heating to afford the reactive clus-
ter Ru3(CO)7(l3-COMe)[l-P(Ph)C@C(PPh2)C(O)CH2C(O)] (4), whose
chemistry with H2 and phosphine ligands has been investigated.
The face-capping P(Ph)C@C(PPh2)C(O)CH2C(O) has been shown to
function as either a 7e- or 9e- donor ligand, in addition to facilitat-
ing the expansion of the Ru3 polyhedron in the reaction of 7 ? 8.
Future studies will explore the catalytic properties of these and
other cluster compounds that contain a coordinative flexible
face-capping P(Ph)C@C(PPh2)C(O)CH2C(O) ligand.
O
2.12 ppm
27.93 ppm
OMe
Me3P
PPh2
Ru
Ru
Me3P
-12.27 ppm
P
Ru
Ph
-52.15 ppm

S.G. Bott et al. / Journal of Organometallic Chemistry 693 (2008) 2327–2337
2337
[15] (a) S.G. Bott, H. Shen, R.A. Senter, M.G. Richmond, Organometallics 22 (2003)
1953;
5. Supplementary material
(b) W.H. Watson, S.G. Bodige, K. Ejsmont, J. Liu, M.G. Richmond, J. Organomet.
Chem. 691 (2006) 3609.
[16] (a) D.J. Darensbourg, Adv. Organomet. Chem. 21 (1982) 113;
(b) M.G. Richmond, J.K. Kochi, Inorg. Chem. 25 (1986) 1334.
[17] (a) K. Yang, S.G. Bott, M.G. Richmond, Organometallics 14 (1995) 919.
2718;
CCDC 617376, 617374, 617375, 617377 and 617378 contain the
supplementary crystallographic data for 4, 5, 7, 8 and 9. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
(b) C.G. Xia, K. Yang, S.G. Bott, M.G. Richmond, Organometallics 15 (1996)
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Acknowledgements
(b) P. Frediani, C. Faggi, S. Papaleo, A. Salvini, M. Bianchi, F. Piacenti, S. Ianelli,
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We thank Prof. Guido F. Verbeck for the use of his mass spec-
trometer and Ms. Nicole Ledbetter for recording the ESI-MS of clus-
ter 9. Financial support from the Robert A. Welch Foundation
(Grant B-1093-MGR) is greatly appreciated.
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