Syntheses, reactivity studies and structural characterisation of triruthenium carbonyl methoxynitrido clusters containing phosphine ligands

Article abstract of DOI:10.1016/S0022-328X(98)00994-2

The substitution reaction of the methoxynitrido cluster, [Ru₃(CO)₉(μ₃-CO)(μ₃-NOMe)] 1 with PPh₃ affords both mono- and di-substituted products with the formulae [Ru₃(CO)₈(μ₃-CO)(μ ₃-NOMe)(PPh₃)] 2 and [Ru₃(CO)₇(μ₃-CO)(μ ₃-NOMe)(PPh₃)₂] 3, respectively. When a bidentate phosphine such as bis(diphenylphosphino)methane (dppm) is used, [Ru₃(CO)₇(μ₃-CO)(μ ₃-NOMe)(μ-dppm)] 4 is formed, in which the dppm ligand replaced two equatorial carbonyls from two adjacent Ru centres. Both clusters 3 and 4 are stable when heated, while vacuum pyrolysis of 2 yields a di-isocyanate cluster [Ru₃(CO)₈(μ-NCO)₂(PPh₃) ₂] 5 with the two isocyanate ligands spanning over the open RuRu edge on both sides of the Ru₃ plane.

Full text of DOI:10.1016/S0022-328X(98)00994-2

Journal of Organometallic Chemistry 575 (1999) 200–208
Syntheses, reactivity studies and structural characterisation of
triruthenium carbonyl methoxynitrido clusters containing phosphine
ligands
Kenneth Ka-Hong Lee, Wing-Tak Wong *
Department of Chemistry, The Uni6ersity of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong
Received 21 July 1998
Abstract
The substitution reaction of the methoxynitrido cluster, [Ru3(CO)9(v3-CO)(v3-NOMe)] 1 with PPh3 affords both mono- and
di-substituted products with the formulae [Ru3(CO)8(v3-CO)(v3-NOMe)(PPh3)] 2 and [Ru3(CO)7(v3-CO)(v3-NOMe)(PPh3)2] 3,
respectively. When a bidentate phosphine such as bis(diphenylphosphino)methane (dppm) is used, [Ru3(CO)7(v3-CO)(v3-
NOMe)(v-dppm)] 4 is formed, in which the dppm ligand replaced two equatorial carbonyls from two adjacent Ru centres. Both
clusters 3 and 4 are stable when heated, while vacuum pyrolysis of 2 yields a di-isocyanate cluster [Ru3(CO)8(v-NCO)2(PPh3)2] 5
with the two isocyanate ligands spanning over the open Ru···Ru edge on both sides of the Ru3 plane. © 1999 Elsevier Science S.A.
All rights reserved.
Keywords: Ruthenium; Cluster; Methoxynitrido; Phosphine; Isocyanate
1. Introduction
detailed reaction pathways leading to these compounds
have been elucidated so far. Recently, the phosphine-
substituted derivative of the closely related nitrene clus-
ters [Ru3(CO)9(v3-CO)(v3-NPh)] [5] was synthesised
which, substantially assisted our investigation of the
substitution reaction of the methoxynitrido cluster,
[Ru3(CO)9(v3-CO)(v3-NOMe)] in two directions. First of
all, we extended our investigation into the chemistry of
methoxynitrido clusters in the hope of developing the
chemical reactivity of those newly synthesised substi-
tuted methoxynitrido clusters by varying both their
electronic and structural features. Furthermore, we be-
lieve that introducing a phosphine ligand may give us
some insight into the understanding of possible mecha-
nisms for the formation of these nitrido and nitrene
species. This is because the molecular symmetry of the
phosphine containing derivatives are lower and the
interpretation of spectroscopic data will be simpler. In
addition the use of these clusters as starting materials for
the preparation of v4-nitrene containing species allows
the metal core rearrangement process to be determined.
In previous papers, the triruthenium methoxynitrido
clusters, [Ru3(CO)9(v3-CO)(v3-NOMe)] and [Ru3(v-
H)2(CO)9(v3-NOMe)] were reported to be synthetic pre-
cursors for nitrido and/or nitrene species [1–3] such as
[Ru4(CO)12(v4-N)(v-OMe)], [Ru6(CO)13(v-CO)(v5-N)-
(v3-NH)(v3-OMe){v-p2-C(O)OMe}2] and [Ru6(CO)16-
(v-CO)2(v4-NH)(v-OMe)(v-R)] (where R=H, OMe
and NCO). The isolation of the quadruply bridging
nitrene (v4-NH) containing clusters is particularly inter-
esting since this moiety has only been isolated success-
fully
once
from
the
protonation
of
the
[Ru4(v4-N)(CO)12]− anion, in the presence of dipheny-
lacetylene as a structural stabiliser [4]. The polynuclear
v4-NH species formed from the methoxynitrido clusters
are believed to originate from the thermolytic N–O bond
cleavage of the methoxynitrido moiety. However, no
* Corresponding author. Fax: +852-25472933; e-mail: wt-
wong@hkucc.hku.hk.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)00994-2

K. Ka-Hong Lee, W.-T. Wong / Journal of Organometallic Chemistry 575 (1999) 200–208
201
Table 1
Spectroscopic data for clusters 2–5
a
b
b
c
Cluster
IR (wCO), cm−1
1H-NMR, l
31P-NMR, l
42.20
MS, m/z
2
3
4
2084s, 2057s, 2020vs, 2015sh, 1996s, 7.45 [m, 15H, phenyl], 3.52 [s, 3H, methoxy]
1958m, 1716s
2062s, 2022s, 2005vs, 1970s, 1943m, 7.46 [m, 30H, phenyl], 3.51 [s, 3H, methoxy]
1684m
2068s, 2018vs, 2004s, 1988w,
1976m, 1960w, 1713m
862 (862)
1096 (1096)
956 (956)
42.74, 35.88
7.43 [m, 10H, phenyl], 7.19 [m, 6H, phenyl], 7.03 [m, 4H, 25.44
phenyl], 3.97 [q, JPH 12.2Hz, 1H, –CH2–], 3.43 [q, JPH
11.4Hz, 1H, –CH2–], 3.18 [s, 3H, methoxy]
5
2179vs, 2071s, 2019s, 2003m, 1953w 7.25 [m, 30H, phenyl]
21.27
1135 (1135)
a Recorded in CH2Cl2.
b Recorded in CD2Cl2.
c Calculated value in parentheses.
2. Results and discussion
and dichloromethane at room temperature. The molec-
ular structure of 2 and some selected bond parameters
of 2 are depicted in Fig. 1 and Table 2, respectively.
The molecule of 2 is closely related to the structure of
1 with one of the axial carbonyl groups replaced by a
2.1. Reaction of cluster 1 with triphenylphosphine
The reaction between stoichiometric amounts of both
[Ru3(CO)9(v3-CO)(v3-NOMe)] 1 and triphenylphos-
phine (PPh3), in THF, at room temperature for 3 days
afforded the isolation of two yellow compounds,
[Ru3(CO)8(v3-CO)(v3-NOMe)(PPh3)] 2 and [Ru3(CO)7-
(v3-CO)(v3-NOMe)(PPh3)2] 3 in 29 and 7% yields, re-
spectively. Both 2 and 3 were characterised fully by
spectroscopic methods and the related data are sum-
marised in Table 1.
triphenylphosphine
methoxynitrido metal framework is composed of an
equilateral triruthenium plane with average Ru–Ru
distance of 2.775(1) A which is symmetrically capped
on both sides by a triply-bridged methoxynitrido and
ligand.
The
triruthenium
˚
v3-bridging carbonyl group. The average Ru–N bond
˚
length [2.024(6) A] is comparable to that in 1 (average
˚
Ru–N 2.02(3) A) [6] and [Ru3(CO)9(v3-CO)(v3-NPh)]
˚
(2.054(4) A) [7]. The N(1)–O(10) bond length is found
The IR spectra of 2 and 3 resembled closely the
mono- and di-substituted phenylimido derivatives
[Ru3(CO)9−n(v3-CO)(v3-NPh)(PPh3)n] (where n=1 or
2) which have been reported previously by Bott and
Richmond from the reaction of [Ru3(CO)9(v3-CO)(v3-
NPh)] with triphenylphosphine [5]. The formulations of
2 and 3 were established first by positive mass spectra
which are consistent with triruthenium species on the
˚
to be 1.414(8) A, and is slightly shorter than that in 1
˚
(1.433(6) A). The PPh3 ligand is co-ordinated in an
˚
axial position with Ru(3)–P(1) distance of 2.377(2) A.
The molecular structure of 3, from X-ray structural
analysis, is shown in Fig. 2 while the important struc-
tural parameters are given in Table 3. The molecule of
3, as expected, consists of a central triruthenium
methoxynitrido core similar to the structures of 1 and 2
except that there are two co-ordinated phosphine lig-
ands attached by two separate metal centres. The solu-
tion spectroscopic data including the 31P-NMR
spectroscopic properties is consistent with the solid
state structure. The solution spectrum of 3 revealed the
presence of two different resonances for the phosphorus
nuclei at 42.74 and 35.88 ppm for the PPh3 moieties in
the axial and equatorial position respectively. The
metal-metal bonds within the ruthenium triangle span a
1
basis of the patterns of peak envelopes. The H-NMR
spectra of 2 and 3 are similar in that they both show
proton resonances attributable to the phenyl rings and
methoxy group only, but the relative intensities are in
ratios of 5:1 and 10:1, respectively. However, the 31P-
NMR spectra provided additional information about
the orientation of the PPh3 ligands in the co-ordinated
compounds. In contrast to a singlet at 42.20 ppm for
cluster 2, the spectrum of 3 revealed the presence of two
singlet peaks with almost equal intensity at 42.74 and
35.88 ppm which were assigned to both axial and
equatorial co-ordinated phosphine ligands. In addition
to the signals due to the terminal CO, the IR of both 2
and 3 showed their characteristic wCO for the triply
˚
narrow range from 2.758(2) to 2.798(2) A while the
nitrogen atom of the methoxynitrido ligand is capped
slightly asymmetrically (Ru(1)–N(1) 2.02; Ru(2)–N(1)
˚
2.01(1) and Ru(3)–N(1) 2.036(1) A) over the triruthe-
bridging carbonyl groups at 1716 and 1684 cm−1
respectively.
,
nium core so that the methoxynitrido moiety is dis-
placed away from the metal centre with co-ordinated
PPh3 in an equatorial position. The two Ru–P bonds
are almost equi-distant at (average 2.382(1) A) but are
slightly longer than that in 2 (2.377(2) A).
Crystals of both 2 and 3 with qualities suitable for
X-ray analysis were obtained by slow evaporation of
their respective saturated solution mixtures of n-hexane
˚
˚

202
K. Ka-Hong Lee, W.-T. Wong / Journal of Organometallic Chemistry 575 (1999) 200–208
Fig. 1. The molecular structure of [Ru3(CO)8(v3-CO)(v3-NOMe)(PPh3)] 2 with the atom numbering scheme.
and may be favourable for catalysis. For example,
[Ru3(CO)10(v-dppm)] had proved to be an active cata-
lyst in the reductive carbonylation of nitrobenzene [8]
in a solvent mixture of toluene+methanol at 170°C
and 60 atm. of CO which afforded the corresponding
carbamate, PhN(H)C(O)OMe.
2.2. Reaction of cluster 1 with bidentate phosphine
ligand
As cluster 1 is shown to readily undergo substitution
of carbonyl groups by mono-dentate phosphine ligands
to give phosphine-substituted methoxynitrido clusters
which exhibit greater stability when compared with the
parent compound. As a continuation, the synthesis of
[Ru3(CO)7(v3-CO)(v3-NOMe)(v-dppm)] was desired
since previous studies of clusters bearing bidentate lig-
ands have shown that they usually give extra stability
Treatment of 1 with a stoichiometric quantity of
bis(diphenylphosphino)methane, dppm in THF at room
temperature for 3 d afforded other than the starting
compound 1, the isolation of two compounds,
[Ru3(CO)7(v3-CO)(v3-NOMe)(v-dppm)] 4 and [Ru3-
(CO)10(v-dppm)] in 35 and 5% yields, respectively, as
shown in Scheme 1. Cluster 4 can be obtained also in
much higher yields with the aid of a stoichiometric
amount of the decarbonylating reagent, Me3NO in
which the transient mono-co-ordinated [Ru3(CO)8(v3-
CO)(v3-NOMe)(dppm)] is formed after the reaction
mixture has been stirred for several hours. Cluster 4 has
been characterised fully and the spectroscopic data
tabulated in Table 1. Similar to clusters 1, 2 and 3, the
IR spectrum of 4 reveals a sharp v3-CO stretching at
Table 2
˚
Selected bond lengths (A) and angles (°) of cluster 2 with estimated
S.D. in parentheses
˚
Bond lengths (A)
Ru(1)–Ru(2)
Ru(1)–Ru(3)
Ru(2)–N(1)
Ru(3)–P(1)
O(10)–C(10)
2.765(1)
2.784(1)
2.014(6)
2.377(2)
1.41(1)
Ru(2)–Ru(3)
Ru(1)–N(1)
Ru(3)–N(1)
N(1)–O(10)
2.777(1)
2.028(6)
2.030(6)
1.414(8)
1
1713cm−1. In the H-NMR spectrum, in addition to
Bond angles (°)
Ru(1)–Ru(2)–Ru(3) 60.31(3)
Ru(1)–Ru(3)–Ru(2) 59.64(3)
Ru(2)–Ru(1)–Ru(3) 60.06(2)
the resonance due to the methoxy group (3.18 ppm),
signals responsible for the dppm were observed at l
7.43–7.03 (phenyl) and 3.97–3.43 (–CH2–). The 31P-
NMR spectrum suggested also the equivalent of two
Ru(1)–N(1)–Ru(2)
Ru(1)–N(1)–Ru(3)
N(1)–O(10)–C(10)
86.3(3)
86.6(2)
112.7(7)
Ru(2)–N(1)–Ru(3)
Ru(2)–Ru(3)–P(1)
86.7(2)
125.61(6)

K. Ka-Hong Lee, W.-T. Wong / Journal of Organometallic Chemistry 575 (1999) 200–208
203
Fig. 2. The molecular structure of [Ru3(CO)7(v3-CO)(v3-NOMe)(PPh3)2] 3 with the atom numbering scheme.
is in good agreement with the spectroscopic data. The
molecule of 4 consists essentially of a triruthenium
methoxynitrido core (similar to 1, 2 and 3) with the
bidentate dppm ligand, chelated on the Ru(2) and
Ru(3) atoms, similar to the geometry of [Ru3(CO)7(v3-
CO)(v3-NPh)(v-dppm)] [8]. The three Ru–Ru bonds
are essentially equi-distant (Ru(1)–Ru(2) 2.756(1),
phosphorus atoms since only a singlet at 25.44 ppm was
observed. The identity of the di-substitution of 4 by
dppm was concluded by the positive mass spectrum
which showed a parent ion peak centred at m/z 956
with a subsequent loss of eight carbonyl groups.
The molecular structure of 4 as determined by X-ray
crystallography is depicted in Fig. 3 whereas some
selected bond parameters are tabulated in Table 4.
Single crystals of suitable size were grown by the diffu-
sion of diethyl-ether into a saturated CH2Cl2 solution
of 4 at room temperature. The solid-state structure of 4
˚
Ru(2)–Ru(3) 2.792(1) and Ru(1)–Ru(3) 2.747(1) A)
while the nitrogen atom is capped symmetrically over
the metal core with an average Ru–N distance of
˚
2.029(5) A. The bidentate dppm ligand is spanned over
the edge Ru(2)–Ru(3) whereas the two phosphorus
atoms occupy the equatorial position with an average
Table 3
˚
˚
Ru–P separation of 2.338(3) A which lies within a
Selected bond lengths (A) and angles (°) of cluster 3 with estimated
S.D. in parentheses
reasonable range to those values found in
˚
[Ru3(CO)7(v3-CO)(v3-NPh)(v-dppm)] (2.344 A) [8a]
˚
Bond lengths (A)
˚
and [Ru3(CO)7(v3-NPh)2(v-dppm)] (2.323 A) [9]. Ex-
Ru(1)–Ru(2)
Ru(1)–Ru(3)
Ru(2)–N(1)
Ru(2)–P(1)
N(1)–O(9)
2.798(2)
2.787(2)
2.01(1)
2.382(4)
1.44(1)
Ru(2)–Ru(3)
Ru(1)–N(1)
Ru(3)–N(1)
Ru(3)–P(2)
O(9)–C(9)
2.758(2)
2.02(1)
2.036(10)
2.381(4)
1.44(2)
cept for three CO bounded to Ru(1), both Ru(2) and
Ru(3) are co-ordinated by two terminal carbonyls to
give a precise cluster valence electron count of 48.
Bond angles (°)
2.3. Thermolytic reaction of clusters 2–4
Ru(1)–Ru(2)–Ru(3) 60.22(4) Ru(2)–Ru(1)–Ru(3) 59.19(4)
Ru(1)–Ru(3)–Ru(2) 60.60(4) Ru(1)–N(1)–Ru(2) 88.1(4)
Ru(2)–N(1)–Ru(3)
N(1)–O(9)–C(9)
It was shown previously that thermolysis of cluster 1
results in the formation of high nuclearity clusters
containing the quadruply bridging nitrene moiety [1,2].
86.0(4)
113(1)
Ru(1)–N(1)–Ru(3) 86.9(4)

204
K. Ka-Hong Lee, W.-T. Wong / Journal of Organometallic Chemistry 575 (1999) 200–208
Scheme 1.
mass spectrum of 5 exhibits a parent ion peak centred
at m/z 1135 with an envelope distribution characteristic
of three ruthenium atoms. In order to establish the
molecular structure of 5, crystals suitable for X-ray
analysis were obtained by slow evaporation of a
dichloromethane solution of 5 at −20°C.
However, no unambiguous mechanism has been drawn
so far. As a result, the phosphine-substituted deriva-
tives of cluster 1 were chosen in order to study their
thermolytic behaviour, in the hope of obtaining some
v4-nitrene containing clusters which may give us some
understanding of its formation.
The molecular structure of 5, together with some
important structural parameters, is depicted in Fig. 4
and Table 5, respectively. The crystal packing of 5
contains two CH2Cl2 molecules in the asymmetric unit
as solvents of crystallisation. The molecule of 5 consists
of an open triruthenium metal core with two isocyanate
moieties bridged over the open Ru···Ru edge at both
sides of the Ru3 plane. The two Ru–Ru bonds are
As expected, those phosphine-derivatives, particu-
larly clusters 3 and 4 are thermodynamically more
stable than the parent cluster 1 since thermolysis of
them in common high-boiling organic solvents such as
toluene and n-octane does not give any observable
change. In fact, the majority of the starting materials
are stable when heated with very minor decomposition
only. In comparison, cluster 2 seems to be more vulner-
able and its thermolytic behaviour is focused upon
especially.
Vacuum pyrolysis of cluster 2 in the solid state at
140°C afforded a number of yellow bands in which the
relatively abundant one, [Ru3(CO)8(v-NCO)2(PPh3)2] 5,
was isolated (Scheme 1) and characterised by various
spectroscopic methods (Table 1). The presence of co-or-
dinated PPh3 ligands in 5 is revealed from both 1H- and
31P-NMR spectra of 5 in which the former shows a
multiplet centred at l 7.25 for the phenyl groups, while
the latter signal indicates the chemical equivalent of
two co-ordinated phosphine groups at 21.27 ppm. The
IR spectrum of 5 shows the presence of a terminal
carbonyl with a strong stretching frequency at 2179
cm−1 which is assigned to the w(CO) of NCO. The
˚
almost equi-distant (average 2.831(1) A) while
Ru(2)···Ru(3) is essentially non-bonding with a separa-
˚
tion of 3.078(1) A. The two isocyanate ligands are
spanned symmetrically over the open edge with an
˚
average Ru–N distance of 2.183(9) and 2.178(1) A and
result in dihedral angles of 118.9 and 119.9° with
respect to the triruthenium plane. Within the isocyanate
groups, the mean N–C and C–O bonds are 1.155(1)
˚
and 1.205(1) A, respectively which are in accordance
with the reported values found in [Ru4(v-H)3(v-
˚
NCO)(CO)12] (N–C 1.153(7) and C–O 1.179(7) A) [10].
The two isocyanate ligands are essentially linear with
an average N–C–O bond angle of 177(1)°. Two addi-
tional PPh3 ligands are co-ordinated to Ru(2) and
Ru(3) in an equatorial position in contrast to 3. The

K. Ka-Hong Lee, W.-T. Wong / Journal of Organometallic Chemistry 575 (1999) 200–208
205
Fig. 3. The molecular structure of [Ru3(CO)7(v3-CO)(v3-NOMe)(v-dppm)] 4 with the atom numbering scheme.
˚
average Ru–P distance is also lengthened (2.408(1) A)
i.e. di-substituted products such as clusters 3 and 4 are
˚
˚
when compared to 2 (2.377(2) A) and 3 (2.382(4) A).
Together with the two 3e-donating isocyanate ligands,
the co-ordination sphere of 5 is filled with eight termi-
nal CO and two PPh3 ligands to give an electron count
of 50, which is in accordance with the CVE count of
triruthenium complex with two metal–metal bonds.
more thermally stable than cluster 2 since the latter
may undergo thermolysis to give the isocyanate cluster
5. The structural consequence for the generation of two
v-bridging isocyanate moieties in cluster 5 may be
similar to that of our cluster example characterised
previously,
[Ru6(CO)16(v-CO)2(v4-NH)(v-OMe)(v-
NCO)], since both were formed in a condition of high
CO pressure. Although cluster 5 was only isolated as
one of the products in the reaction mixture, characteri-
sation of the remaining products proceeded with
difficulty since their respective yields were extremely
low. From the colour of the products isolated from the
reaction mixture, it is unlikely to have cluster-deriva-
tives bearing the quadruply bridging nitrene (v4-NH)
moieties formed from the pyrolysis of 2 since all of our
v4-NH containing clusters characterised previously pos-
sess a distinctive blue colour.
3. Conclusions
The incorporation of phosphine ligands to the
triruthenium methoxynitrido cluster enhanced the ther-
mal stability of the ruthenium compounds. The relative
stabilities were reflected by the degree of substitution,
Table 4
˚
Selected bond lengths (A) and angles (°) of cluster 4 with estimated
S.D. in parentheses
˚
Bond lengths (A)
Ru(1)–Ru(2)
Ru(1)–Ru(3)
Ru(2)–N(1)
Ru(2)–P(1)
N(1)–O(9)
2.756(1)
2.747(1)
2.032(8)
2.314(3)
1.431(10)
1.83(1)
Ru(2)–Ru(3)
Ru(1)–N(1)
Ru(3)–N(1)
Ru(3)–P(2)
O(9)–C(9)
2.792(1)
2.029(8)
2.027(8)
2.362(3)
1.41(1)
4. Experimental
4.1. General procedures
P(1)–C(22)
P(2)–C(22)
1.84(1)
All manipulations were carried out under an inert
atmosphere of argon with standard Schlenk technique,
unless stated otherwise. Chemicals were used as re-
ceived without further purification, unless stated other-
wise. Trimethylamine-N-oxide was dried by azeotropic
distillation and sublimed prior to use. Solvents were
dried according to standard methods. Preparative thin-
Bond angles (°)
Ru(1)–Ru(2)–Ru(3) 59.34(3)
Ru(1)–Ru(3)–Ru(2) 59.67(3)
Ru(2)–N(1)–Ru(3)
Ru(2)–P(1)–C(22)
N(1)–O(9)–C(9)
Ru(2)–Ru(1)–Ru(3) 60.99(3)
Ru(1)–N(1)–Ru(2)
Ru(1)–N(1)–Ru(3)
Ru(3)–P(2)–C(22)
85.5(3)
85.2(3)
110.0(3)
86.9(3)
111.0(3)
111.3(7)

206
K. Ka-Hong Lee, W.-T. Wong / Journal of Organometallic Chemistry 575 (1999) 200–208
Fig. 4. The molecular structure of [Ru3(CO)8(v-NCO)(PPh3)2] 5 with the atom numbering scheme.
layer chromatographic (TLC) plates were prepared
from silica (Merck Kieselgel 60 GF254). Infrared spectra
were recorded on a Bio-rad FTS-165 FT-IR spectrome-
perature for 3 days. The orange solution was then dried
in vacuo and the residue was separated by preparative
TLC using n-hexane/CH2Cl2 (2:1, v/v) as the eluent.
Three distinct bands were observed together with a
number of minor bands of yellow colour. The first
yellow band with Rf:0.7 was identified as the unre-
acted 1 (25 mg, 20%) from IR spectroscopy. Two
yellow bands were followed and characterised as
[Ru3(CO)8(v3-CO)(v3-NOMe)(PPh3)] 2 (50mg, 29%,
Rfꢀ0.5) and [Ru3(CO)7(v3-CO)(v3-NOMe)(PPh3)2] 3
(15mg, 7%, Rf:0.3). The yield of cluster 2 can be
increased by up to 65% when the reaction is carried out
with the slow addition of a CH2Cl2 solution of one
equivalent of Me3NO. Similarly, cluster 3 can be ob-
tained also in relatively higher yields (\40%) accompa-
nied with 2 (25%) when two equivalents of both PPh3
and Me3NO were used instead.
1
ter using 0.5 mm CaF2 solution cells. H-NMR spectra
were obtained on a Bruker DPX-300 NMR spectrome-
ter using deuteriated solvents as lock and reference.
Fast-atom bombardment (FAB) mass spectra were
recorded on a Finnigan MAT 95 mass spectrometer.
Elemental analyses were performed by the Butterworth
Laboratories, UK.
4.2. Reaction of [Ru3(CO)9(v3-CO)(v3-NOMe)] 1 with
triphenylphosphine
The solid of 1 (126 mg, 0.2 mmol) and triphenylphos-
phine (53 mg, 0.2 mmol) were dissolved in 50 cm3 THF.
The yellow solution was allowed to stir at room tem-
4.3. Reaction of [Ru3(CO)9(v3-CO)(v3-NOMe)] 1 with
dppm
Table 5
˚
Selected bond lengths (A) and angles (°) of cluster 5 with estimated
S.D. in parentheses
Solid of 1 (188 mg, 0.3 mmol) and dppm (115 mg, 0.3
mmol) were dissolved in 60 cm3 THF to give a yellow
solution. After stirring for 3 days, the solvent was
removed from the resultant orange solution in vacuo.
The residue was subjected to preparative TLC using
n-hexane/CH2Cl2 (2:3, v/v) as the eluent. Three distinct
yellow bands were observed in order of elution as
unreacted 1 (30 mg, 16%, Rf:0.9), [Ru3(CO)10(v-
dppm)] (15 mg, 5%, Rf:0.7) and [Ru3(CO)7(v3-
CO)(v3-NOMe)(v-dppm)] 4 (100 mg, 35%, Rf:0.4)
together with a few uncharacterised yellow minor
bands.
˚
Bond lengths (A)
Ru(1)–Ru(2)
Ru(1)···Ru(3)
Ru(3)–N(1)
Ru(3)–N(2)
Ru(3)–P(2)
C(9)–O(9)
2.826(1)
3.078(1)
2.173(10)
2.173(10)
2.410(4)
1.21(2)
Ru(1)–Ru(3)
Ru(2)–N(1)
Ru(2)–N(2)
Ru(2)–P(1)
N(1)–C(9)
2.836(1)
2.193(9)
2.182(10)
2.405(4)
1.14(2)
N(2)–C(10)
1.17(1)
C(10)–O(10)
1.20(1)
Bond angles (°)
Ru(2)–Ru(1)–Ru(3) 65.87(3)
Ru(2)–N(2)–Ru(3) 90.0(3)
N(2)–C(10)–O(10) 175(1)
Ru(2)–N(1)–Ru(3) 89.7(3)
N(1)–C(9)–O(9) 178(1)

K. Ka-Hong Lee, W.-T. Wong / Journal of Organometallic Chemistry 575 (1999) 200–208
207

208
K. Ka-Hong Lee, W.-T. Wong / Journal of Organometallic Chemistry 575 (1999) 200–208
4.4. Vacuum pyrolysis of [Ru3(CO)8(v3-CO)(v3NOMe)-
(PPh3)] 2
refined by full-matrix least-squares analysis on F with
all non-hydrogen atoms refined anisotropically until
convergence was reached. Hydrogen atoms of the or-
ganic moieties were generated in their ideal positions
A solid sample of 2 (50 mg, 0.058 mmol) was dis-
solved in 5 cm3 of CH2Cl2. The yellow solution was
then introduced into a flame-dried Carius tube. The
solvent was removed under reduced pressure to give a
thin layer of 2 deposited on the inner wall of the
pyrolysis tube. The tube was placed in an oven at
140°C for 1 h. The dark residue was extracted exhaus-
tively with CH2Cl2. The combined extract was then
concentrated to a few cm3 and purified by preparative
TLC using n-hexane/CH2Cl2 (3:2, v/v) as the eluent to
give a series of minor bands with colours ranging from
yellow to red. Characterisation of two major bands
revealed the presence of some unreacted 2 (3 mg, 6%,
Rf:0.7) and [Ru3(CO)8(v-NCO)2(PPh3)2] 5 (yellow,
Rf:0.5) which was isolated as a yellow solid in 20%
yield.
˚
(C–H, 0.95 A). They are included in the structure
factors calculations but were not refined. All calcula-
tions were performed on a Silicon-Graphics computer
using the program package TEXSAN [14].
Atomic co-ordinates, thermal parameters, and bond
lengths and angles have been deposited at the Cam-
bridge Crystallographic Data Centre (CCDC).
Acknowledgements
W.-T. Wong acknowledges financial support from
the Hong Kong Research Grants Council and the
University of Hong Kong. K. Ka-Hong Lee acknowl-
edges the receipt of a postgraduate studentship, admin-
istered by the University of Hong Kong.
4.5. X-ray crystal structure determination
Single crystals of 2-5 for X-ray analyses were ob-
tained as described above. Crystals of clusters 2 and 3
were mounted separately on top of a glass fibre by
means of epoxy resin while clusters 4 and 5 were sealed
in Lindemann glass capillaries. Crystal intensity data
were collected on either a Rigaku-AFC7R or a MAR
research image-plate scanner using graphite-monochro-
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[3] K.K.H. Lee, W.T. Wong, Inorg. Chem. 35 (1996) 5393.
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[5] H. Shen, R.A. Senter, S.G. Bott, M.G. Richmond, Inorg.
Chim. Acta. 247 (1996) 161.
˚
mated Mo–Kh radiation (u=0.71073 A) for unit-cell
determination and data collection. Summary of the
crystallographic data, structure solution and refinement
are given in Table 6. The ꢀ–2q scan mode with speed
16.0 deg. min−1 was used for complexes 2 and 3. For
clusters 4 and 5, 65 3° frames with an exposure time of
5 min per frame were used. Lorentz-polarisation and
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the intensity data collected on a Rigaku-AFC7R dif-
fractometer. However, only Lorentz and polarisation
effects were corrected for 4 and 5. An approximation to
absorption correction by inter-image scaling was made.
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.