Synthesis and isomerisation of two metallated N,O-complexes of ruthenium: Models for the Murai reaction

Article abstract of DOI:10.1016/j.ica.2005.05.021

Two isomers of the N,O-coordinated acetylpyrrolyl complex [Ru(PPh ₃)₂(CO)(NC₄H₃C(O)CH₃)H] {cis-N,H (1) and trans-N,H (2)} have been prepared as models for catalytic intermediates in the Murai reaction. Complex 2 isomerises to 1 upon heating via a dissociative pathway (ΔH^? = 195 ± 41 kJ mol^-1; ΔS^? = 232 ± 62 J mol ^-1 K^-1); the mechanism of this process has been modeled using density functional calculations. Complex 2 displays moderate catalytic activity for the Murai coupling of 2′-methylacetophenone with trimethylvinylsilane, but 1 proved to be catalytically inactive under the same conditions.

Full text of DOI:10.1016/j.ica.2005.05.021

Inorganica Chimica Acta 359 (2006) 815–820
www.elsevier.com/locate/ica
Synthesis and isomerisation of two metallated N,O-complexes
of ruthenium: Models for the Murai reaction
a
Rodolphe F.R. Jazzar , Maurizio Varrone , Andrew D. Burrows
Stuart A. Macgregor *, Mary F. Mahon , Michael K. Whittlesey
a
a,
*
,
b,
a
a,
*
a
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
b
Received 23 March 2005; accepted 20 May 2005
Available online 28 June 2005
Ruthenium and Osmium Chemistry Topical Issue.
Abstract
Two isomers of the N,O-coordinated acetylpyrrolyl complex [Ru(PPh3)2(CO)(NC4H3C(O)CH3)H] {cis-N,H (1) and trans-N,H
(2)} have been prepared as models for catalytic intermediates in the Murai reaction. Complex 2 isomerises to 1 upon heating via
a dissociative pathway (DHà = 195 41 kJ molꢀ1; DSà = 232 62 J molꢀ1 Kꢀ1); the mechanism of this process has been modeled
using density functional calculations. Complex 2 displays moderate catalytic activity for the Murai coupling of 20-methylacetoph-
enone with trimethylvinylsilane, but 1 proved to be catalytically inactive under the same conditions.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Ruthenium complexes; Phosphine ligands; Hydride ligands; Cyclometallation; Murai reaction; Density functional theory
1. Introduction
C@O or C@N functionality; subsequent activation gives
an ortho-metallated complex such as A–D (Scheme 1)
[3,4]. The actual ancillary ligands and their relative ste-
reochemistry in this reactive C–H activated complex,
however, remain to be elucidated. In most mechanistic
studies, a coordinatively unsaturated species such as A
has been assumed, although there are somewhat con-
flicting data as to the presence of CO and how it impacts
on the overall catalytic activity [5]. Hiraki and co-work-
ers [6] have reported that reaction of [Ru(PPh3)3-
(CO)H2] with styrene/p-(trifluoromethyl)acetophenone
initially forms compounds B and C (characterised on
the basis of 1H and 31P NMR studies), although the on-
set of ketone–alkene coupling only occurs upon forma-
tion of isomer D later in the reaction.
The increasing need for atom efficient organic reac-
tions has attracted much attention in the field of homo-
geneous catalysis, with transition metal mediated C–H
bond activation the focus of considerable interest [1].
Murai and co-workers [2] have developed one of the
most potentially useful classes of reactions involving a
Ru-catalysed coupling of alkenes with aromatic ketones,
esters, imines, etc. Fundamental to the catalysis is the
role of chelation assistance, in which the metal is an-
chored close to the reactive aromatic C–H bond by the
*
Corresponding authors. Tel.: +44 1225 386529 (A.D. Burrows),
+44 131 451 8023 (S.A. Macgregor), +44 1225 383748 (M.K.
Whittlesey); fax: +44 1225 386231 (A.D. Burrows), +44 131 451
3180 (S.A. Macgregor), +44 1225 386231 (M.K. Whittlesey).
E-mail addresses: a.d.burrows@bath.ac.uk (A.D. Burrows),
S.A.Macgregor@hw.ac.uk (S.A. Macgregor), m.k.whittlesey@bath.
ac.uk, chsmkw@bath.ac.uk (M.K. Whittlesey).
Following on from our earlier studies [7] that dealt
with the catalytic activity of complexes related to C,
we set out to make analogues incorporating hemilabile
N-pyrrolyl ketophosphines rather than PPh3. We now
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.05.021

816
R.F.R. Jazzar et al. / Inorganica Chimica Acta 359 (2006) 815–820
CF3
CF3
CF3
OC
PPh3
Ru
PPh3
Ru
PPh3
Ru
PPh3
Ru
H
H
OC
Ph3P
O
OC
O
PPh3
H
O
PPh3
Ph3P/OC
O
H
A
D
C
B
Scheme 1. Stereochemical arrangements of potential intermediates in the Murai reaction.
PPh3
Ru
PPh3
Ru
CH
3
C
O
N
PPh
OC
Ph3P
H
H
OC
H
O
N
2
1
2
toluene, ∆
PPh3
PPh3
∆
PPh3
Ru
PPh3
Ru
CH
3
C
O
N
H
O
N
H
O
N
H
CO
Ru(PPh3)3(H2)H2
thf, ∆
Ph3P
OC
PPh3
PPh3
Scheme 2. Formation of 1 and 2.
report that serendipitously, such ligands undergo facile
degradation allowing isolation of the N,O-coordinated
complex 1. This and an isomeric species 2 are useful
model intermediates for the Murai reaction.
pyrrole in THF at 50 ꢁC to give, as expected
[Ru(PPh3)3(NC4H3C(O)CH3)H] [10]. Addition of CO
to this complex at room temperature failed to give 1,
affording instead a second stereoisomer, trans-N,H-
[Ru(PPh3)2(CO)(NC4H3C(O)CH3)H] (2), in which the
hydride ligand was trans to the pyrrolyl nitrogen. Iden-
tification of 2 as an isomer of 1 was readily apparent
from the different chemical shifts of the hydride (d
ꢀ9.39, JHP = 20.8 Hz) and carbonyl (d 207.1,
JCP = 13.5 Hz) resonances. The appearance of mCO for
2 at 1917 cmꢀ1 in the IR spectrum (cf. 1927 cmꢀ1 in 1)
is consistent with orientation of the carbonyl group
trans to the p-donating oxygen. Identification of 2 as
the trans-N,H isomer of 1 was confirmed by X-ray
crystallography.
2. Results and discussion
The reaction of [Ru(PPh3)3(CO)H2] with a slight ex-
cess of PPh2(NC4H3C(O)CH3-2) under reflux conditions
unexpectedly afforded the acetylpyrrole complex cis-
N,H-[Ru(PPh3)2(CO)(NC4H3C(O)CH3)H] (1) in a rea-
sonable yield (Scheme 2). The stereochemistry of 1 was
established through a combination of multinuclear
NMR spectroscopy and X-ray crystallography. Thus,
1 shows a single phosphorus resonance, a triplet hydride
signal (1H: d ꢀ13.91, JHP = 20.4 Hz) and a low field trip-
2.1. Molecular structures of 1 and 2
let carbonyl resonance (13C{1H}:
d 204.9, JCP =
13.0 Hz). The solid state structure of 1 (Fig. 1, Table
1) is discussed below. In an attempt to establish the fate
of the ÔmissingÕ Ph2PH moiety, the reaction was followed
by 31P{1H}NMR spectroscopy. After 12 h at 80 ꢁC, the
31P{1H} spectrum showed unreacted [Ru(PPh3)3(CO)-
H2], PPh2(NC4H3C(O)CH3), 1, 2 [8] and free PPh3. No
other species was present in >5% yield. We have previ-
ously shown that PPh2(NC4H3C(O)CH3-2) can undergo
metal-promoted hydrolysis of the P–N bond to give
diphosphoxane (PPh2OPPh2) products [9], though 1 is
the first example in which we have isolated a compound
containing the acetylpyrrolyl fragment of the N-pyrrolyl
phosphine.
The X-ray crystal structure of 2 is shown alongside
that for 1 in Fig. 1. Comparison of the metric data for
1 and 2 (Table 1) reveals the expected lengthening of
the Ru–X bond trans to hydride; thus, in 1, the Ru–O
˚
distance is 2.212(2) A compared to an Ru–O bond
˚
length of 2.1391(14) A in 2. Very little difference is ob-
served between the metallated acetylpyrrole rings in
the two complexes.
2.2. Experimental and DFT study of the conversion of 2–1
Upon heating a toluene-d8 solution of 2 at 80 ꢁC, clean
but incomplete isomerisation to 1 was observed by H
1
In an effort to find a more convenient and logical
route to 1 [Ru(PPh3)3(H2)H2] was treated with 2-acetyl-
NMR spectroscopy over the course of 5 h [11]. An Eyring
plot for the reaction measured over the range 80–100 ꢁC

R.F.R. Jazzar et al. / Inorganica Chimica Acta 359 (2006) 815–820
817
Fig. 1. Molecular structures of 1 and 2. Thermal ellipsoids are shown at the 30% probability level.
Table 1
puted structures are in generally good agreement with
those determined crystallographically, in particular the
longer Ru–O and Ru–N bonds observed when trans to
hydride are nicely reproduced. We compute 10 to be
8 kJ molꢀ1 more stable than 20, consistent with the exper-
imental observation that 1 is thermodynamically pre-
ferred over 2. Two possible routes for the isomerisation
of 20 to 10 have been studied. In Pathway A, 20 first loses
PH3 to give a square-pyramidal 5-coordinate species, 20-
P (E = +66.5 kJ molꢀ1), in which H occupies an apical
position and the pyrrole arm of the chelating ligand has
moved into the site vacated by PH3. Isomerisation of
20-P proceeds via aꢀtr1igonal bipyramidal transition state
(E = +115.8 kJ mol ) to give square-pyramidal 10-P,
(E = +110.8 kJ molꢀ1) which can then add PH3 to gener-
ate 10. Pathway B involves decoordination of the acetyl
moiety from 20, a process that leads to a new 5-coordinate
species, 20-O (E = +83.2 kJ molꢀ1). During this process
the pyrrole arm again moves away from the site trans
to hydride and moves trans to CO. Rotation around
the Ru–N bond in 20-O then leads directly to 10 via
Selected bond lengths and angles for complexes cis-N,H-[Ru(PPh3)2-
(CO)(NC4H3C(O)CH3)H] (1) and trans-N,H-[Ru(PPh3)2(CO)(NC4H3-
C(O)CH3)H] (2)
1
2
Ru(1)–C(43)
Ru(1)–O(2)
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–N(7)
O(1)–C(43)
N(7)–C(37)
O(2)–C(41)
1.834(3)
2.212(2)
Ru(1)–C(7)
Ru(1)–O(1)
1.815(2)
2.1391(14)
2.3319(4)
2.3404(5)
2.1551(19)
1.281(3)
2.3496(7) Ru(1)–P(1)
2.3598(7) Ru(1)–P(2)
2.118(2)
1.154(4)
1.336(4)
1.273(4)
Ru(1)–N(1)
O(1)–C(5)
N(1)–C(1)
O(1)–C(5)
1.338(3)
1.281(3)
P(1)–Ru(1)–P(2)
O(2)–Ru(1)–P(1)
O(2)–Ru(1)–P(2)
C(43)–Ru(1)–P(2)
O(2)–Ru(1)–P(2)
N(7)–Ru(1)–P(1)
N(7)–Ru(1)–P(2)
C(41)–O(2)–Ru(1)
C(43)–Ru(1)–O(2)
172.41(3)
98.06(5)
88.76(5)
90.78(9)
88.76(5)
87.71(6)
90.73(6)
113.84(19)
99.14(12)
P(1)–Ru(1)–P(2)
O(1)–Ru(1)–P(1)
O(1)–Ru(1)–P(2)
C(7)–Ru(1)–P(2)
O(1)–Ru(1)–P(2)
N(1)–Ru(1)–P(1)
N(1)–Ru(1)–P(2)
C(5)–O(1)–Ru(1)
C(7)–Ru(1)–O(1)
171.47(2)
90.51(4)
88.91(4)
89.42(7)
88.91(4)
95.46(5)
92.69(5)
114.74(14)
176.65(7)
C(40)–N(7)–Ru(1) 113.63(18)
O(2)–C(41)–C(40)
N(7)–C(40)–C(41)
C(4)–N(1)–Ru(1) 111.62(14)
O(1)–C(5)–C(4)
N(1)–C(4)–C(5)
119.2(3)
117.4(3)
119.74(19)
116.67(19)
TS2 -O to 1 (E = 109.6 kJ molꢀ1). Comparing Pathways
A and B shows the computed enthalpies of activation
to be around 110 kJ molꢀ1 in each case. This is somewhat
lower than the experimental value, probably due to the
simplifications we have employed in our models. How-
ever, Pathway A entails a significant, favourable entropy
contribution which suggests it would be far more accessi-
ble on the free energy surface (DGà = +76.9 kJ molꢀ1 for
Pathway A cf. +118.8 kJ molꢀ1 for Pathway B) and on
this basis we propose an isomerisation pathway based
0
0
gave highly positive values for both DHà
(195 41 kJ molꢀ1) and DSà (232 62 J molꢀ1 Kꢀ1).
To elucidate possible pathways for this isomerisation
reaction, density functional calculations were run
employing model systems of the form [Ru(PH3)2-
(CO)(NC4H3C(O)H)H], 10 (H cis to N, a model for 1)
and 20 (H trans to N, a model for 2, Fig. 2) [12]. The com-

818
R.F.R. Jazzar et al. / Inorganica Chimica Acta 359 (2006) 815–820
Fig. 2. Computed free energy profiles (kJ molꢀ1) and key distances (A) for the isomerisation of 1 –2 via Pathways A and B. Computed enthalpies,
0
0
˚
corrected to 298.15 K, are given in plain text while free energies are given in italics.
on phosphine dissociation would be operative. This is
consistent with the large positive entropy of activation
determined experimentally.
from potassium/benzophenone. [Ru(PPh3)3(CO)H2]
[2c], [Ru(PPh3)3(H2)H2] [13] and PPh2(NC4H3C(O)CH3)
[14] were prepared according to the literature. NMR
spectra were recorded on Varian Mercury 400 or Bruker
Avance 400 and 300 MHz NMR spectrometers and ref-
erenced to C6D5H (1H: d 7.15) or C6D6 (13C{1H}: d
128.0). 31P{1H}NMR chemical shifts were referenced
externally to 85% H3PO4 (d 0.0). Elemental analyses
were performed at the University of Bath.
To assess the activity of 1 and 2 as catalyst precursors
for Murai chemistry, the coupling of 20-methylacetoph-
enone with trimethylvinylsilane was studied in toluene at
135 ꢁC. Complex 1 showed zero activity even after 2
days, whereas 2 gave 23% of the coupling product after
only 2 h. Although 2 shows only moderate activity (pre-
sumably due to the competing isomerisation to 1), the
fact that 1 is completely inactive only reinforces the
argument that the stereochemical arrangement of phos-
phine ligands, metallated ketone, hydride and probably
CO warrants further investigation in trying to under-
stand the ruthenium catalysed Murai reaction.
3.2. Synthesis of cis-N,H-[Ru(PPh3)2(CO)-
(NC4H3C(O)CH3)H] (1)
A flame-dried Schlenk tube equipped with a magnetic
stirring bar was charged with [Ru(PPh3)3(CO)H2]
(0.50 g, 0.51 mmol), PPh2(NC4H3C(O)CH3) (0.20 g,
0.66 mmol) and 10 mL toluene. The mixture was re-
fluxed for 2 h to give a dark red solution. Removal of
the solvent gave a dark red oil. 25 mL of methanol were
added and the mixture stirred for 3 h to give a pink
tinged white precipitate. The solid was isolated by filter
cannula, washed with methanol (3 · 10 mL) and hexane
(1 · 10 mL) and finally dried under vacuum to afford
0.18 g (43%) of product. Anal. Calc. for RuC43H37-
P2O2N (762.8): C, 67.70; H, 4.88; N, 1.83. Found: C,
3. Experimental
3.1. General considerations
Manipulations were carried out using standard
Schlenk, high vacuum and glovebox techniques. All sol-
vents were distilled under nitrogen using standard proce-
dures. C6D6 and C6D5CD3 were vacuum transferred

R.F.R. Jazzar et al. / Inorganica Chimica Acta 359 (2006) 815–820
819
1
Table 2
Crystal structure details for compounds 1 and 2
67.7; H, 4.99; N, 1.90%. H NMR (C6D6, 400 MHz,
293 K): d 7.57 (br m, 10H, C6H5), 6.99 (br m, 20H,
C6H5), 6.58 (br d, JHH = 4.0 Hz, 1H), 6.51 (br s, 1H),
6.02 (dd, JHH = 1.2 Hz, JHH = 4.0 Hz, 1H), 1.67 (s,
3H, CH3), ꢀ13.91 (t, JPH = 20.4 Hz, 1H, Ru–H).
31P{1H} NMR (C6D6, 293 K): d 48.2 (s). 13C{1H}
(C6D6, 293 K): d 204.9 (t, JCP = 13.0 Hz, Ru–CO),
188.5 (br s, Ru–O@C), 142.4 (s), 140.2 (s), 134.0 (t,
JCP = 21.0 Hz), 134.0 (t, JCP = 6.0 Hz), 129.2 (s), 128.0
(s), 119.7 (s), 114.5 (s), 22.4 (s, CH3). IR (nujol, cmꢀ1):
2037 (mRu–H), 1927 (mCO), 1535 (mRu–O@C).
Compound number
1
2
Molecular formula
Formula weight
T (K)
C49H43NO2P2Ru C49H43NO2P2Ru
840.85
150(2)
840.85
150(2)
monoclinic
P21
Crystal system
Space group
Unit cell dimensions
monoclinic
P21/c
˚
a (A)
9.6410(1)
18.3800(3)
22.7660(3)
95.0860(9)
4018.29(9)
4
13.0850(1)
11.7580(1)
13.3760(2)
99.811(1)
2027.85(4)
2
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
U (A )
3.3. Synthesis of [Ru(PPh3)3(NC4H3C(O)CH3)H]
Z
Dc (g cmꢀ3
)
1.390
0.511
1736
1.377
0.506
868
l (mmꢀ1
F(000)
Crystal size (mm)
)
To a suspension of [Ru(PPh3)3(H2)H2] (0.20 g,
0.22 mmol) in 5 mL THF was added an excess of 2-acet-
ylpyrrole (0.34 g, 3.10 mmol). The mixture was heated
with stirring at 50 ꢁC for 12 h. The solution was concen-
trated to yield a pale yellow precipitate, which was fil-
tered off, washed with hexane (3 · 10 mL) and dried in
vacuo. Yield 0.20 g, 92%. 31P{1H} NMR (C6D6): 63.2
(t, JPP = 29.1 Hz), 50.8 (d, JPP = 29.1 Hz).
0.50 · 0.40 · 0.20 0.30 · 0.25 · 0.25
h Range (ꢁ)
Index ranges
2.91–27.50
0 6 h 6 12;
ꢀ23 6 k 6 23;
ꢀ29 6 l 6 29
58254
3.54–30.04
ꢀ18 6 h 6 18;
ꢀ16 6 k 6 16;
ꢀ18 6 l 6 18
38730
Reflections collected
Independent reflections, Rint
Reflections observed
[I > 2r(I)]
9191, 0.0754
6879
11675, 0.0325
10885
3.4. Synthesis of trans-N,H-
[Ru(PPh3)2(CO)(NC4H3C(O)CH3)H] (2)
Absorption correction
Data/restraints/parameters
Goodness-of-fit on F2
Final R1, wR2 indices
[I > 2r(I)]
none
0.894, 0.851
11675/2/482
1.042
9191/0/502
0.747
0.0375, 0.0927
0.0298, 0.0749
A benzene suspension (10 mL) of [Ru(PPh3)3(NC4H3-
C(O)CH3)H] (0.60 g, 0.60 mmol) was stirred under
1 atm of carbon monoxide for 30 min, during which
time the color changed from pale yellow to colourless.
The solution was concentrated and hexane added
(10 mL) to give an off-white precipitate. This was fil-
tered, washed with 2 · 10 mL hexane and dried in va-
cuo. Yield 0.40 g, 87%. Anal. Calc. for
RuC43H37P2O2N (762.8): C, 67.70; H, 4.88; N, 1.83.
R indices (all data)
Maximum and minimum
0.0664, 0.1138
0.0335, 0.0769
0.606 and ꢀ0.462 0.657 and ꢀ0.624
ꢀ3
˚
residual density (e A
)
Absolute structure parameter
ꢀ0.036(14)
vent (benzene) in addition to one molecule of the metal
complex. The hydrogen atoms attached to the metal
centres were readily located in both structures. In com-
pound 1 the hydride was freely refined, while in 2 it was
refined at a distance of 1.6 A from the ruthenium. Con-
vergence was otherwise uneventful in both cases.
1
Found: C, 67.5; H, 4.94; N, 1.82%. H NMR (C6D6,
400 MHz, 293 K): d 7.66 (br m, 10H, C6H5), 6.99 (br
m, 21H, C6H5 + H), 6.69 (br d, JHH = 3.6 Hz, 1H, H),
6.27 (dd, JHH = 1.6 Hz, JHH = 4.0 Hz, 1H), 1.42 (s,
3H, CH3), ꢀ9.39 (t, JPH = 20.8 Hz, 1H, Ru-H).
˚
31P{1H}NMR
(C6D6,
293 K):
d
48.5
(s).
3.6. Computational details
13C{1H}(C6D6, 293 K): d, 207.1 (t, JCP = 13.5 Hz, Ru–
CO), 188.2 (br s, Ru–O@C), 143.4 (s), 141.2 (s), 134.7
(t, JCP = 21.1 Hz), 134.4 (t, JCP = 6.1 Hz), 129.4 (s),
128.1 (s), 120.3 (s), 115.2 (s), 21.8 (s, CH3). IR (nujol,
cmꢀ1): 1962 (mRu–H), 1917 (mCO), 1536 (mRu–O@C).
Density functional calculations employed the GAUS-
SIAN 98 program [12] and the BP86 functional combina-
tions. Ru and P centres were described using the
Stuttgart RECPs and the associated basis sets [17a].
For P an extra set of polarisation functions was added
(f = 0.387) [17b]. The 6-31G** basis set was used for
all other atoms directly bound to Ru and for the car-
bonyl oxygen while the 6-31G basis set was employed
for all other atoms [17c,17d]. Stationary points were
characterized as either minima (0 imaginary frequencies)
or transition states (1 imaginary frequency) via analyti-
cal frequency calculations and energies incorporate
zero-point energies and temperature effects corrected
to 298.15 K.
3.5. Crystallography
Single crystals of compounds 1 and 2 were analysed
using a Nonius Kappa CCD diffractometer. Details of
the data collections, solutions and refinements are given
in Table 2. The structures were both solved using
SHELXS-97 [15,16] and refined using full-matrix least-
squares in SHELXL-97 [15,16]. The asymmetric unit in
both structures was seen to contain one molecule of sol-

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R.F.R. Jazzar et al. / Inorganica Chimica Acta 359 (2006) 815–820
[4] Chelation assistance may not always be needed. X. Zhang, M.
Acknowledgements
Kanzelberger, T.J. Emge, A.S. Goldman, J. Am. Chem. Soc. 126
(2004) 13192.
We thank EPSRC (studentships for RFRJ and MV),
the University of Bath and Heriot-Watt University for
financial support. Johnson Matthey plc are acknowl-
edged for the loan of ruthenium trichloride.
[5] (a) B.M. Trost, K. Imi, I.W. Davies, J. Am. Chem. Soc. 117
(1995) 5371;
(b) Y. Guari, S. Sabo-Etienne, B. Chaudret, J. Am. Chem. Soc.
120 (1998) 4228;
(c) S. Busch, W. Leitner, Chem. Commun. (1999) 2305;
(d) S.D. Drouin, D. Amoroso, G.P.A. Yap, D.E. Fogg, Organo-
metallics 21 (2002) 1042;
Appendix A. Supplementary data
(e) Y. Guari, A. Castellanos, S. Sabo-Etienne, B. Chaudret, J.
Mol. Cat. A 212 (2004) 77.
[6] K. Hiraki, T. Ishimoto, H. Kawano, Bull. Chem. Soc. Jpn. 73
(2000) 2099.
Computed energies and Cartesian coordinates of all
stationary points are also available. Crystallographic
data for compounds 1 and 2 have been deposited with
the Cambridge Crystallographic Data Centre as supple-
mentary publications CCDC 266837 and 266838,
respectively. Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK [fax: +44 1223 336033, e-mail: de-
posit@ccdc.cam.ac.uk]. Supplementary data associated
with this article can be found, in the online version, at
doi:10.1016/j.ica.2005.05.021.
[7] R.F.R. Jazzar, M.F. Mahon, M.K. Whittlesey, Organometallics
20 (2001) 3745.
[8] We assume that the resonance for 2 results from some isomeri-
sation of 1 under the high temperature conditions employed rather
than being a direct product from reaction of [Ru(PPh3)3(CO)H2]
with PPh2(NC4H3C(O)CH3).
[9] A.D. Burrows, M.F. Mahon, M.T. Palmer, M. Varrone, Inorg.
Chem. 41 (2002) 1695.
[10] Previously [7], we showed that relative stereochemistry is retained
upon converting [Ru(PPh3)3(o-C6H4C(O)CH3)H] to [Ru(PPh3)2(-
CO)(o-C6H4C(O)CH3)H]. It seems reasonable to assume that the
stereochemistry in [Ru(PPh3)3(NC4H3C(O)CH3)H] is the same as
that in 2.
[11] The isomerisation of related cyclometallated N-benzylideneaniline
and 2-phenylpyridine complexes of ruthenium has been described.
K. Hiraki, M. Koizumi, S. Kira, H. Kawano, Chem. Lett. (1998)
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