Syntheses, structure characterisation and X-ray studies of some mono, di- and tri-substituted cluster complexes of Ru3(CO)12 substituted by bulky fluorinated phosphine ligands

Article abstract of DOI:10.1016/j.poly.2010.11.022

Five trinuclear substituted complexes of the type Ru₃(CO) ₁₁L, Ru₃(CO)₁₀L₂ and Ru ₃(CO)₉L₃ were synthesised by the reaction of Ru₃(CO)₁₂ with flu

Full text of DOI:10.1016/j.poly.2010.11.022

Polyhedron 30 (2011) 444–450
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Syntheses, structure characterisation and X-ray studies of some mono, di- and
tri-substituted cluster complexes of Ru3(CO)12 substituted by bulky fluorinated
phosphine ligands
Omar bin Shawkataly a, ,1, Mohd. Aslam A. Pankhi a, Mohd. Gulfam Alam a, Chin Sing Yeap b,
⇑
Hoong-Kun Fun b
a Chemical Sciences Programme, School of Distance Education, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
b X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
a r t i c l e i n f o
a b s t r a c t
Article history:
Five trinuclear substituted complexes of the type Ru3(CO)11L, Ru3(CO)10L2 and Ru3(CO)9L3 were synthes-
ised by the reaction of Ru3(CO)12 with fluorine substituted phosphine ligands, {P(C6H4F-m)3 and P(C6H4F-
p)3}, using the radical anion catalysed method. The structures of the resulting clusters were elucidated by
means of elemental analyses and spectroscopic methods, which included IR, 1H, 13C and 31P NMR spec-
troscopy. X-ray crystallographic studies of four of the complexes were carried out. In all the complexes,
the ligand occupies an equatorial position due to steric reasons, and coordination of the ligand is
observed only at the phosphorus atom. In the two monosubstituted complexes, Ru3(CO)11P(C6H4F-m)3
and Ru3(CO)11P(C6H4F-p)3, the effect of substitution resulted in an increase in the Ru–Ru distances.
Out of the three Ru–Ru bonds, the one which is cis to the ligand is noticeably longer than the other
two. The asymmetric unit of the disubstituted complex Ru3(CO)10{P(C6H4F-p)3}2 is composed of two mol-
ecules, A and B. As expected, the two phosphorus ligands are equatorially bonded to two different ruthe-
nium atoms. The asymmetric unit of the trisubstituted complex is composed of one molecule of
Ru3(CO)9{P(C6H4F-m)3}3 and one disordered solvent molecule. The structure consists of one triangular
ruthenium complex in which each of the phosphorus ligands is equatorially bonded to three different
ruthenium atoms. In the structure, disorder of the fluorine atoms is observed. Bond parameters, espe-
cially bond lengths and bond angles, are correlated to the structure and also are compared with the lit-
erature data of similar compounds.
Received 1 September 2010
Accepted 9 November 2010
Available online 5 December 2010
Keywords:
Ruthenium
Cluster
Carbonyl
Phosphines
X-ray diffraction
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
synthesis of mono, di- and tri-substituted clusters of Ru3(CO)12, tri-
methylamine oxide-induced carbonyl substitution [6], bis(triphen-
The chemistry of metal carbonyl clusters has always attracted
researchers’ interest, not only from the synthetic angle but also be-
cause of their application in catalysis [1]. The thermal reaction of
Ru3(CO)12 with PR3 in general leads to the mono, di- and tri-substi-
tuted derivatives, i.e., {Ru3(CO)11(PR3)}, {Ru3(CO)10(PR3)2}, and
{Ru3(CO)9(PR3)3} [2]. An earlier method reported by Bruce et al.
was the displacement method, whereby the complex Ru3(-
CO)11(CNBut) was made to react with CO or a ligand containing
P, As or Sb as a donor element, by displacing CO or CNBut [3].
The usefulness of this process has been successively demonstrated
for synthesising monosubstituted complexes of Os3(CO)12 by the
reaction of Os3(CO)11(MeCN) with PR3 [4,5]. For the direct
ylphosphine)iminium salt-catalysed carbonyl substitution [7] and
radical anion catalysed ligand substitution [8a,b] methods have
been developed. However, we prefer the radical anion method, as
developed by Bruce et al., to synthesise derivatives of the type
Ru3(CO)12ꢀnLn [n = 1, 2, 3, 4], substituted by tertiary phosphines,
phosphites, arsines and isocyanides [9a,b]. Substitution of CO by
a more bulky ligand results in the latter occupying the sterically
least demanding site, which in all cases is the equatorial site.
Phosphine ligands have found extensive use in the formation of
many complexes of ruthenium over the years. It has been observed
that the substitution of phosphine ligands for carbonyls may in-
crease the catalytic activity for hydrogenation–isomerization reac-
tions of linear dienes [10]. Homogeneous hydrogenation of
diphenylacetylene in the presence of Ru3(CO)9L3 has also been
studied [11]. While complexes of many phosphine substituted
Ru3(CO)12 have been studied by Bruce et al., and they summarised
that it proved difficult to obtain X-ray quality crystals of the series
⇑
Corresponding author. Tel.: +60 4 653 3936; fax: +60 4 657 6000.
E-mail address: omarsa@usm.my (O.b. Shawkataly).
On secondment to: Multimedia University, Melaka Campus, Jalan Ayer Keroh
1
Lama, 74750 Melaka, Malaysia.
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.11.022

O.b. Shawkataly et al. / Polyhedron 30 (2011) 444–450
445
of complexes Ru3(CO)12ꢀnLn, in which the CO group is progressively
substituted by the same phosphine ligand [12].
moved under reduced pressure to give an oily mass. Thin layer
chromatography showed the presence of two spots, one of them
being a trace amount of the starting material, Ru3(CO)12. This
Some examples of n = 1–3 and n = 1–4 have been reported, but
substitution by bulky phosphines makes it increasingly more diffi-
cult. Recently, the synthesis, structural characterisation and X-ray
studies of some monosubstituted complexes of the type Ru3(-
CO)11L have been studied in our laboratory [13]. To further our
interest on the substituted triangle ruthenium clusters, we report
the synthesis and characterisation of Ru3(CO)11P(C6H4F-m)3 (1),
Ru3(CO)9{P(C6H4F-m)3}3 (2), Ru3(CO)11P(C6H4F-p)3 (3), Ru3(-
CO)10{P(C6H4F-p)3}2 (4) and Ru3(CO)9{P(C6H4F-p)3}3 (5). X-ray dif-
fraction studies of complexes 1–4 were carried out, however a
similar study of complex 5 was not undertaken as attempts to ob-
tain suitable single crystals for X-ray studies were not successful.
It has been observed that the introduction of non-CO ligands in
general to Ru3(CO)12 result in the lengthening of the Ru–Ru bond.
The effect was more prominent in the two monosubstituted com-
plexes 1 and 3. A disorder of the fluorine atoms has been observed
in the two complexes (1 and 2) where P(C6H4F-m)3 has been used
as the ligand. In light of other published reports on substituted
clusters of Ru3(CO)12 with phosphine ligands, this study enables
us to make a detailed comparison on the molecular geometries
which results from substitution of CO.
was identified by its IR v(CO) spectrum with that of an authentic
sample. The major orange band was separated by column chroma-
tography and characterised. Yield: 97.5 mg (67%), m.p. 147–149 °C.
Anal. Calc. for Ru3C29H12O11F3P: C, 37.55; H, 1.30. Found: C, 37.59;
H, 1.28%. IR (cyclohexane),
v
(CO): 2099(m), 2049(m), 2017(s) and
1988(m) cmꢀ1
.
1H NMR (CDCl3): d 7.05–7.55 (m, 12H, Ph); 13C
NMR (CDCl3): d 118.3–164.6 (m, Ph), 204.0 (m, CO); 31P NMR
(CDCl3): d 37.3 (s, P ligand). Crystals suitable for X-ray crystallogra-
phy were grown by solvent/solvent diffusion of n-hexane/dichloro-
methane at 10 °C.
2.2.2. Synthesis of Ru3(CO)9{P(C6H4F-m)3}3 (2)
Compound 2 was prepared in a similar way to compound 1, by
reacting Ru3(CO)12 and P(C6H4F-m)3 in a 1:3 ratio. TLC of the reac-
tion showed three bands. The major red-purple band was sepa-
rated by preparative thin layer chromatography (Rf: 0.32,
hexane:dichloromethane 70:30) and characterised. Yield:
87.7 mg (62%), m.p. 166–168 °C. Anal. Calc. for Ru3C63H36O9F9P3:
C, 50.31; H, 2.41. Found: C, 50.27; H, 2.39%. IR (cyclohexane),
v
(CO): 2058(m), 2041(m), 1989(s) and 1980(s) cmꢀ1 1H NMR
.
(CDCl3): d 7.05–7.55 (m, Ph); 13C NMR (CDCl3): d 117.8–164.5 (m,
Ph), 204.2 (m, CO); 31P NMR (CDCl3): d 39.2 (s, P ligand). Crystals
suitable for X-ray crystallography were grown by solvent/solvent
diffusion of n-hexane/dichloromethane at 10 °C.
2. Experimental
2.1. Chemicals, starting materials and spectroscopic measurements
2.2.3. Synthesis of Ru3(CO)11P(C6H4F-p)3 (3)
All the syntheses were carried out using standard Schlenk tech-
niques under an atmosphere of oxygen-free nitrogen. Ru3(CO)12
(Aldrich), P(C6H4F-m)3 and P(C6H4F-p)3 (Maybridge Chem. Co.
Ltd., UK) were used as received. Tetrahydrofuran was distilled from
sodium benzophenone ketyl under an oxygen-free nitrogen atmo-
sphere. The radical anion method was used for the syntheses of the
complexes [14]. AR grade solvents were used for crystallisation.
Florisil (100–200 mesh, Acros) was used as the stationary phase
for column chromatography. Preparative TLC was carried out on
glass plates, 20 ꢁ 20 cm, using Silica gel 60GF254 (Merck). Hexane
and dichloromethane of AR grades were used for elution during
column chromatography and preparative TLC. Elemental analyses
were performed using a Perkin–Elmer model 2400 LS Series II C,
H, N analyser, USA. Melting points of the compounds were per-
formed in open capillaries using a SMP1 melting point apparatus,
UK and were uncorrected. IR spectra were recorded with a Per-
kin–Elmer System 2000 FTIR spectrometer in a NaCl solution cell
(0.1 mm). Deuterated chloroform was used as a solvent for 1H,
13C and 31P NMR studies. These NMR studies were carried out on
a Bruker B2H 400 FT-NMR spectrometer using 5 mm tubes. The
1H and 13C NMR shifts were referenced to TMS and 31P NMR shifts
were referenced to 85% H3PO4. All the complexes were synthesised
by the reaction between Ru3(CO)12 and a stoichiometric amount of
the appropriate ligand. The resulting complexes were separated by
chromatographic techniques and then isolated in the pure form. All
the complexes were characterised by microanalyses and their
spectral studies.
Ru3(CO)12 (100 mg, 0.16 mmol) and P(C6H4F-p)3 (52 mg,
0.17 mmol) were reacted in a similar way to compound 1. Thin
layer chromatography showed the presence of two spots, one of
them being a trace amount of the starting material, Ru3(CO)12
.
The major orange band was separated by column chromatography
and characterised. Yield: 94.0 mg (64.8%), m.p. 154–156 °C. Anal.
Calc. for Ru3C29H12O11F3P: C, 37.55; H, 1.30. Found: C, 37.58; H,
1.32%. IR (cyclohexane),
v
(CO): 2099(m), 2059(w), 2048(m),
2017(s) and 1988(s) cmꢀ1
.
1H NMR (CDCl3): d 7.1–7.5 (m, 12H,
Ph); 13C NMR (CDCl3): d 116.4–166.1 (m, Ph), 204.4 (m, CO); 31P
NMR (CDCl3) d 34.2 (s, P ligand). Crystals suitable for X-ray crystal-
lography were grown by solvent/solvent diffusion of n-hexane/
dichloromethane at 10 °C.
2.2.4. Synthesis of Ru3(CO)10{P(C6H4F-p)3}2 (4)
Compound 4 was prepared in a similar way to compound 1, by
reacting Ru3(CO)12 and P(C6H4F-p)3 in a 1:2 molar ratio. Separation
of the products was done by preparative TLC which showed three
bands. The major red band was separated (Rf: 0.44, hexane:dichlo-
romethane 78:22) and characterised. Yield: 79.0 mg (52%), m.p.
178–179 °C. Anal. Calc. for Ru3C46H24O10F6P2: C, 45.44; H, 1.99.
Found: C, 45.41; H, 1.97%. IR (cyclohexane),
v(CO): 2079(m),
2057(m), 2021(s) and 1997(s). 1H NMR (CDCl3): d 7.05–7.55 (m,
24H, Ph); 13C NMR (CDCl3): d 115.5–164.5 (m, Ph), 204.5 (m,
CO); 31P NMR (CDCl3): d 34.2 (s, P ligand). Crystals suitable for X-
ray crystallography were grown by solvent/solvent diffusion of n-
hexane/dichloromethane at 10 °C.
2.2. Synthesis of the metal complexes
2.2.5. Synthesis of Ru3(CO)9{P(C6H4F-p)3}3 (5)
Compound 5 was prepared in a similar way to compound 1, by
reacting Ru3(CO)12 and P(C6H4F-p)3 in a 1:3 ratio. TLC of the reac-
tion showed three bands. The major red-purple band was sepa-
rated by preparative thin layer chromatography (Rf: 0.34,
hexane:dichloromethane 68:32) and characterised. Yield:
94.6 mg (67%), m.p. 169–171 °C. Anal. Calc. for Ru3C63H36O9F9P3:
C, 50.31; H, 2.41. Found: C, 50.32; H, 2.42%. IR (cyclohexane),
2.2.1. Synthesis of Ru3(CO)11P(C6H4F-m)3 (1)
Ru3(CO)12 (100 mg, 0.16 mmol) and P(C6H4F-m)3 (52 mg,
0.17 mmol) in 10 ml dry deoxygenated THF were heated in an oil
bath and warmed to 40 °C to dissolve the Ru3(CO)12. Sodium ben-
zophenone ketyl solution (5 drops) was added dropwise via syr-
inge, which immediately turned the reaction solution red. After
completion of the reaction (monitored by TLC), the solvent was re-
v
(CO) 2059(m), 2045(w), 2018(w)1988(s) and 1974(s) cmꢀ1
.

446
O.b. Shawkataly et al. / Polyhedron 30 (2011) 444–450
1HNMR (CDCl3): d 7.05–7.50 (m, Ph); 13C NMR (CDCl3): d 116.0–
164.5 (m, Ph), 204.0 (m, CO); 31P NMR (CDCl3): d 36.4 (s, P ligand).
All attempts to grow suitable single crystals of this compound for
X-ray diffraction studies were not successful.
115–166 ppm, characteristic of phenyl carbons. The longer range
was due to the carbons attached to the electronegative fluorine
atoms, which were downfield, and these aromatic carbons were
observed in the range d 160–166 ppm. The carbonyl carbons in
all the five clusters showed a multiplet, as a single broad peak.
The broadness of the single peak in the 13C NMR suggests that
the carbonyl ligands of the triruthenium clusters are fluxional in
solution. A similar observation was made by Lam et al. when they
investigated the reaction of 2-indolylphosphines with Ru3(CO)12
[17]. 31P NMR spectra of the two monosubstituted clusters showed
single signals at d 37.3 and 34.2 ppm for clusters 1 and 3 respec-
tively. For the disubstituted cluster Ru3(CO)10{P(C6H4F-p)3}2, 4, a
single signal was expected in the 31P spectrum as both the ligands
are in identical chemical environments, however due to back-
ground noise, splitting of the signal is observed at d 34.2, whereas
a single signal is observed for the tri-substituted cluster complexes
2 and 5, as all the phosphorus atoms in these complexes are in the
same environment.
2.3. X-ray structural determination
Determination of cell constants and data collection were carried
out at 100.0(1) K using the Oxford Cryosystem Cobra low-temper-
ature attachment with Mo Ka radiation (k = 0.71073 Å) on a Bruker
SMART APEX2 CCD area-detector diffractometer equipped with a
graphite monochromator [15]. The data were reduced using SAINT
[15]. A semi-empirical absorption correction was applied to the
data using SADABS [15]. The structure was solved by direct methods
and refined against F2 by full-matrix least-squares using SHELXTL
[16]. Hydrogen atoms were placed in calculated positions. Crystal
data and experimental details of the structure determinations are
listed in Table 1. All hydrogen atoms were positioned geometri-
cally and refined using a riding model with C–H = 0.93–0.97 Å
and Uiso(H) = 1.2 or 1.5Ueq(C). Details of all hydrogen bonding
geometries are listed in Table 2.
3.2. X-ray crystal structural analysis
3.2.1. Molecular structures of Ru3(CO)11P(C6H4F-m)3 (1) and
Ru3(CO)11P(C6H4F-p)3 (3)
3. Results and discussion
The crystal structures of both the monosubstituted complexes 1
and 3 have been determined. The ORTEP plot of Ru3(CO)11P(C6H4F-
m)3 is shown in Fig. 1. The ORTEP plot of Ru3(CO)11P(C6H4F-p)3, 3, is
shown in Fig. 3. Both the clusters contain a triangular arrangement
of three ruthenium atoms. The coordination of the ligand was only
observed at the phosphorus atom and all ligands occupy equatorial
sites. In Ru3(CO)12, the average Ru–Ru separations is 2.852 Å [18],
one of the three Ru–Ru bonds being slightly longer than the other
two Ru–Ru bonds. The longest Ru–Ru bond in Ru3(CO)12 is 2.859 Å.
In the two monosubstituted complexes 1 and 3, the longest Ru–Ru
bond is the one which is cis to the ligand. For cluster 1, it is
2.905(3) Å and for cluster 3, the longest Ru–Ru bond is
2.876(3) Å. The uneven increase in the length of the metal–metal
3.1. Synthesis and characterisation
The microanalyses of all the compounds agreed well with the
proposed molecular formula for all the reported compounds, with-
in the experimental errors. The isolation of a number of substituted
derivatives of Ru3(CO)12 has enabled definite information on v(CO)
frequencies, and the degree of substitution can be easily estab-
lished from IR spectroscopic studies [8b]. Individual bands, how-
ever, may vary slightly in relative intensity and their position.
The 1H NMR spectra of compounds 1–5 showed a multiplet around
d 7.0–7.6 ppm, characteristic of phenyl groups. The 13C NMR spec-
tra of all the clusters exhibited prominent signals in the range d
Table 1
Crystal data and structure refinement parameters for 1–4.
Compound
1
2
3
4
0
Empirical formula
Formula weight
T (K)
C
29H12F3O11PRu3
C63H36F9O9P3Ru3 C6H14
1590.21
100.0(1)
C29H12F3O11PRu3
927.57
100.0(1)
C46H24F6O10P2Ru3
1215.80
296(2)
927.57
296(2)
k (Å)
0.71073
monoclinic
C2/c
0.71073
triclinic
0.71073
monoclinic
P21/c
0.71073
orthorhombic
Pccn
Crystal system
Space group
Unit cell dimensions
a (Å)
b (Å)
c (Å)
ꢀ
P1
22.3380(2)
16.6337(2)
17.5209(2)
90
104.363(1)
90
6306.65(12)
8
1.954
3584
1.545
0.12 ꢁ 0.26 ꢁ 0.34
1.5–35.1
71 046/13 964
0.047
12.6885(3)
14.4056(3)
18.3377(4)
74.038(1)
83.077(1)
82.258(1)
3180.97(12)
2
13.8320(2)
12.1783(2)
22.4851(3)
90
126.740(1)
90
3035.24(9)
4
2.030
1792
1.606
0.11 ꢁ 0.20 ꢁ 0.22
1.9–30.2
38 310/8911
0.045
22.6851(2)
22.8971(2)
17.7814(2)
90
90
90
9236.07(15)
8
1.749
4768
1.119
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (Mg mꢀ3
F(0 0 0)
)
1.660
1588
0.863
Absorption coefficient (mmꢀ1
Crystal size (mm)
)
0.17 ꢁ 0.30 ꢁ 0.55
0.05 ꢁ 0.17 ꢁ 0.32
1.3–27.5
99 811/10 611
0.075
h Range (°)
Reflections collected/unique
Rint
1.9–32.5
102 284/22 807
0.038
Data/restraints/parameters
Goodness-of-fit on F2
13 964/0/434
1.02
22 807/5/897
1.10
8911/0/424
1.06
10 611/0/605
1.05
Final R indices [I > 2
r
(I)]
R1 = 0.0401
wR2 = 0.0951
R1 = 0.0847
wR2 = 0.1135
ꢀ0.49 and 1.54
R1 = 0.0471
wR2 = 0.1193
R1 = 0.0674
wR2 = 0.1397
ꢀ2.89 and 2.89
R1 = 0.0321
wR2 = 0.0570
R1 = 0.0512
wR2 = 0.0635
ꢀ0.73 and 0.75
R1 = 0.0650
wR2 = 0.1456
R1 = 0.0991
wR2 = 0.1677
ꢀ1.04 and 3.44
R indices (all data)
Largest difference in peak and hole (e Åꢀ3
)

O.b. Shawkataly et al. / Polyhedron 30 (2011) 444–450
447
Table 2
Hydrogen-bonding geometry (Å, °)
D–Hꢂ ꢂ ꢂA
Complex 1
Distance (Å) D–H
0.93
Distance (Å) Hꢂ ꢂ ꢂA
Distance (Å) Dꢂ ꢂ ꢂA
Angle (°) D–Hꢂ ꢂ ꢂA
C15–H15Aꢂ ꢂ ꢂO10i
2.59
3.514(6)
174
Symmetry codes: (i) 1/2 ꢀ x, 1/2 ꢀ y, ꢀz
Complex 2
C8–H8Aꢂ ꢂ ꢂF3Ai
0.93
0.93
0.93
2.43
2.36
2.54
3.062(6)
3.285(8)
3.221(6)
125
169
130
C16–H16Aꢂ ꢂ ꢂF8Aii
C50–H50Aꢂ ꢂ ꢂF1Aiii
Symmetry codes: (i) 1 ꢀ x, 1 ꢀ y, 2 ꢀ z; (ii) 2 ꢀ x, 1 ꢀ y, 2ꢀz; (iii) 2 ꢀ x, ꢀy, 2 ꢀ z
Complex 3
C9–H9Aꢂ ꢂ ꢂF1i
0.93
2.48
3.113(4)
126
Symmetry codes: (i) 2 ꢀ x, 1/2 + y, 1/2 ꢀ z
Complex 4
C12–H12Bꢂ ꢂ ꢂO1B
0.93
0.93
2.59
2.59
3.451(8)
3.389(9)
155
144
C14–H14Aꢂ ꢂ ꢂO1Bi
Symmetry codes: (i) 1/2 + x, ꢀy, 3/2ꢀz
Fig. 1. The ORTEP diagram of complex 1 with 10% probability of ellipsoids for non-H atoms. Only the major disorder component is shown.
bonds in comparison with those in Ru3(CO)12 can be attributed to
the steric effect induced by the bulky substituent. Thus the Ru–Ru
separations in both complexes have ranges of 2.842(3)–2.905(3) Å.
In the monosubstituted complexes of a similar type synthesised by
Bruce et al., the Ru–Ru separations have ranges of 2.839–2.920 Å
[9a].
In clusters 1 and 3, the Ru–P bond lengths are 2.364(7) and
2.349(7) Å respectively which are slightly shorter compare to the
Ru–P bond length of 2.380(6) Å observed for Ru3(CO)11(PPh3), in
which the P atom is similarly bonded equatorially to the ruthe-
nium cluster [19]. In the complexes, the ligand is approximately
trans to one of the Ru–Ru bonds. The Ru–Ru–P angles in the com-
plexes are 103.1(19)° for complex 1 and 113.3(2)° for complex 3.
As observed in Ru3(CO)12, the bonds from the metal atoms to
the axial CO ligands are longer compared to the bonds to the equa-
torial CO groups [20]. In the previously reported structures of Ru3(-
CO)11L, the Ru–CO(ax) distances are longer than the Ru–CO(eq)
distances, the average value of Ru–CO(ax) being 1.939(4) and
1.938(3) Å for clusters 1 and 3 and the average Ru–CO(eq) value
being 1.908(4) and 1.917(3) Å for the two complexes, in the same
order. In Ru3(CO)12, the equatorial Ru–C–O moieties are almost lin-
ear (the average Ru–C–O angle is 178.9°) while the axial Ru–C–O
moieties are slightly bent (average value, 172.9°) [20]. The reason
for this distortion is attributed to the van der Waals repulsion be-
tween the oxygen atoms. In the monosubstituted complexes, the
equatorial CO groups are essentially linear (the average value for
cluster 1 is 177.9° and for cluster 3, it is 177.1°), while the axial
CO groups are slightly bent (average value for cluster 1 is 173.0°
and for cluster 3, it is 174.2°). These observations are consistent
with the previously published observations of monosubstituted
triruthenium cluster complexes [9a]. In Ru (CO)12, the average ax-
ial OC–Ru–CO angles are 178.3° and the average equatorial OC–
Ru–CO angles are 104.1°. In the two monosubstituted complexes
reported here, the average axial OC–Ru–CO angles are 175.3° and

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O.b. Shawkataly et al. / Polyhedron 30 (2011) 444–450
(0.031 Å) than found in Ru3(CO)12, where the corresponding dis-
tance is 2.852 Å [18]. The nine carbonyl ligands are all terminal,
six occupying the two axial positions on the Ru atoms, while the
other three are alternating with the phosphine ligands in one of
the two equatorial positions of each ruthenium atom. The Ru–P
distances are typical of ruthenium complexes of this type, with
an average bond length of 2.337 Å. The three phosphorus atoms
make P–Ru–Ru angles of 165.7(2)°, 167.5(2)° and 170.2(2)°. The
equatorial Ru–C distances [average 1.890 Å] are slightly shorter
than the equatorial Ru–C bond distances of Ru3(CO)12, which aver-
ages 1.924 Å. As expected, upon phosphine substitution, these Ru–
C bond distances are slightly shortened relative to those in
Ru3(CO)12. The Ru–C–O(eq) angles are slightly deviated from linear
(average value 176.0°), while the average Ru–C–O(ax) angle is
slightly bent, with a value of 173.8°. The hexane molecule is disor-
dered over two positions with refined site occupancies of 0.555(7)
and 0.445(7). Seven out of the nine fluorine atoms are disordered
over two positions. The dihedral angles between the three phos-
phine-substituted benzene rings at the P1 atom are 53.8(2)°,
77.4(2)° and 89.60(19)°, at the P2 atom are 55.47(18)°,
80.48(19)° and 86.03(17)°, and at P3 atom are 49.90(19)°,
73.68(19)° and 88.84(19)°.
Fig. 2. The ORTEP diagram of complex 2 with 10% probability of ellipsoids for non-H
atoms. Only the major disorder component is shown. The disordered hexane
solvent is omitted for clarity.
3.2.3. Molecular structure of Ru3(CO)10{P(C6H4F-p)3}2 (4)
The ORTEP plot of cluster 4 is shown in Fig. 4. The asymmetric
unit of Ru3(CO)10{P(C6H4F-p)3}2 consist of two-half molecules (A
and B) of the triruthenium complex. The Ru2A and Ru2B atoms
lie across a two-fold rotation axis. The structure is composed of a
triangle of ruthenium atoms with the two phosphine ligands equa-
torially bonded to two different ruthenium atoms. The two phos-
phine ligands take up positions as far apart as possible. The two
phosphine ligands are approximately trans to the same Ru–Ru
bond, with P–Ru–Ru bond angles of 172.5° and 171.5(5) ° for mol-
ecules A and B. While the P1–Ru1–Ru2 bond angles are 115.6 and
114.5(4)° for both the molecules, in the same order. There is no
noticeable lengthening of the Ru–Ru bond cis to the ligand, and
the Ru–Ru distances are very close to each other. As observed in
Ru3(CO)12 [18], the Ru–CO(ax) bonds are longer than the Ru–CO(eq)
bonds. The Ru–CO(eq) bonds on the metal atom bearing the phos-
phine ligands show the shortest M–CO separations. The Ru–P sep-
arations are identical to those of analogous complexes [22,23]. It
has been observed that Ru–C–O(ax) angles on the metal atoms that
do not bear phosphine ligands have bent significantly from linear-
ity. These Ru–C–O(ax) angles are 167.2(8)° and 168.5(8)° for mole-
cules A and B respectively. The P–Ru–Ru–P dihedral angles are
Fig. 3. The ORTEP diagram of complex 3 with 50% probability of ellipsoids for non-H
atoms.
171.8° for clusters 1 and 3, whereas the average equatorial OC–Ru–
CO angles are 101.6° and 101.4° for the two clusters in the same
order. These observations are also in line with previously pub-
lished reports on monosubstituted complexes [9a].
In complex 1, the dihedral angles between the three phosphine-
substituted benzene rings are 85.94(19)°, 78.7(2)° and 68.72(19)°.
One of the fluorine atoms is disordered over two positions with re-
fined site occupancies of 0.511(6) and 0.489(6). In complex 3, the
dihedral angles between the three phosphine-substituted benzene
rings are 63.53(17)°, 63.72(19)° and 86.84(16)°.
3.2.2. Molecular structure of Ru3(CO)9{P(C6H4F-m)3}3 (2)
The crystal structure of complex 2 has been determined. The OR-
TEP plot of Ru3(CO)9{P(C6H4F-m)3}3 is shown in Fig. 2. The asym-
metric unit consists of one triruthenium complex and one
disordered hexane solvent molecule The three tris{(m-fluoro-
phenyl)phosphine} ligands take up positions that are as far apart
as possible, each occupying an equatorial site. The structure con-
sists of a triangular Ru3 core with three nearly equal Ru–Ru bonds
which posses an average bond length of 2.883 Å. This is close to the
average value of 2.873 Å observed for Ru3(CO)9(PPh3)3 in which the
P atoms are similarly bonded equatorially to the ruthenium cluster
[21]. The average Ru–Ru distance of 2.883 Å is slightly longer
Fig. 4. The ORTEP diagram of complex 4 with 20% probability of ellipsoids for non-H
atoms, only one molecule of the asymmetric unit is shown. The other molecule is of
a similar conformation. The atoms with suffix AA or C are symmetry generated.

O.b. Shawkataly et al. / Polyhedron 30 (2011) 444–450
449
Fig. 5. Comparative study of the rotation about the Ru(CO)4 unit from the plane of the Ru3 triangle.
108.9° and 107.3° for molecules A and B respectively. The dihedral
angles between the three phosphine-substituted benzene rings are
64.2(4)°, 79.8(5)° and 80.0(4)° in molecule A, whereas these angles
are 82.2(4)°, 64.7(4)° and 80.7(4)° in molecule B. In compounds 1–
3, the dihedral angles of the Ru3 plane with the Ru–Ru–C plane are
(Ru1–Ru3–C28) 81.42(13)°, (Ru1–Ru3–C63) 78.61(9)° and (Ru1–
Ru3–C28) 72.81(13)°, respectively. However in compound 4, these
dihedral angles are (Ru1A–Ru2A–C22A) 65.8(2)° and (Ru1B–Ru2B–
C22B) 63.8(3)° in molecules A and B respectively. The twisting of
the Ru(CO)4 unit in cluster 4 is most likely due to the steric hin-
drance of the fluorine substituted on the phenyl ring of the phos-
phine ligand (Fig. 5).
probably due to the presence of electronegative fluorine atoms
substituted on the phenyl ring of the phosphine ligand.
Acknowledgements
The authors would like to thank the Malaysia Government and
Universiti Sains Malaysia (USM) for the Research Grant 1001/
PJJAUH/811115. M.A.A.P. and M.G.A. thank USM for Post doctoral
fellowship. H.K.F. thanks USM for the Research University Golden
Goose Grant 1001/PFIZIK/811012. C.S.Y. also thanks USM for the
award of a USM fellowship.
Appendix A. Supplementary material
4. Conclusion
CCDC 784933, 784934, 784935 and 784936 contain the supple-
mentary crystallographic data for 1, 2, 3 and 4. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk
Some substituted triruthenium cluster carbonyl complexes
were synthesised using fluorine substituted phosphine ligands. In
all the cluster complexes reported, the ligands occupy equatorial
positions, and coordination of the ligands is only at the phosphorus
atom. Due to the steric effect of the ligand, one of the metal–metal
bonds is noticeably longer in the two monosubstituted complexes.
The 13C NMR spectra of all the complexes showed a single broad
peak for CO instead of a multiplet, indicating the fluxional
behaviour of the CO ligands in solution. In the complex Ru3-
(CO)11P(C6H4F-m)3, there is a disorder of one of the fluorine atoms.
Complex Ru3(CO)9{P(C6H4F-m)3}3 shows disorder of the solvent
molecule as well as the fluorine atoms. In the complex Ru3-
(CO)10{P(C6H4F-p)3}2, twisting of the Ru(CO)4 unit is observed,
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