High yield carbonylation of [RuCl2(PPh3) 3] using dimethylformamide (DMF) as convenient source of CO. the X-ray crystal structure of [RuCl2(CO)(DMF)(PPh3) 2]

Article abstract of DOI:10.1016/j.molstruc.2003.11.003

The complex [RuCl₂(CO)(DMF)(PPh₃)₂], was easily synthesized in high yield from [RuCl₂(PPh₃) ₃] and DMF as source of CO. The carbonylated specie has been characterized by X-ray structural an

Full text of DOI:10.1016/j.molstruc.2003.11.003

Journal of Molecular Structure 689 (2004) 137–141
www.elsevier.com/locate/molstruc
High yield carbonylation of [RuCl2(PPh3)3] using dimethylformamide
(DMF) as convenient source of CO. The X-ray crystal structure
of [RuCl2(CO)(DMF)(PPh3)2]
´
Valente Gomez-Benıtez, Jessica Olvera-Mancilla,
Simon Hernandez-Ortega, David Morales-Morales
´
*
´
´
a
´ ´ ´ ´ ´ ´
Instituto de Quımica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, Circuito Exterior, Coyoacan, 04510 Mexico City, Mexico
Received 3 October 2003; revised 4 November 2003; accepted 4 November 2003
Abstract
The complex [RuCl2(CO)(DMF)(PPh3)2], was easily synthesized in high yield from [RuCl2(PPh3)3] and DMF as source of CO.
The carbonylated specie has been characterized by X-ray structural analysis.
q 2004 Elsevier B.V. All rights reserved.
Keywords: Ruthenium complexes; CO-complexes; Carbonylation reactions; DMF activation; Crystal structures; CO abstraction
1. Introduction
through simple analysis (e.g. NMR, infrared) information
regarding whether the desired reaction has proceeded or
not. In this sense, the carbonyl group has been one of the
most studied ligands, [3] due to the fact that is very
sensitive to electronic density changes and it is easily
identifiable by IR or NMR techniques. However, species
containing carbonyl ligands often involve the handling of
poisonous CO gas, [4] therefore methods for the synthesis
of these species using alternative CO sources are desirable.
Thus, we would like to report here that the extremely
attractive starting material [RuCl2(CO)(DMF)(PPh3)2]1
can be synthesized quantitatively by simply refluxing
[RuCl2(PPh3)3] in DMF [6].
The choose for the most adequate starting material for
a specific reaction is perhaps the very first question to
answer before any reaction may take place in a synthetic
research laboratory. Thus, the design and synthesis of
complexes able to provide the desire product is a
continuous topic of research. This is particularly true for
Ruthenium, having multiple applications and due to its
low costenvisioned as the most desirable transition metal
for homogeneous catalysis [1]. It is precisely in this field
where starting materials containing labile molecules (e.g.
solvent molecules) become important, since they can
provide preformed coordination sites otherwise difficult to
form if strong coordinating ligands are present [2].
Another desirable characteristic for this sort of complexes
is that they have to be easy to synthesize, thus, starting
materials containing molecules such as DMSO, MeCN,
THF, etc. have been the choice. The desired complexes
being easily synthesized by plain reflux in the afore
mentioned solvents. Moreover, the final product in these
reactions often include ligands sensitive enough to provide
1
Although the complex [RuCl2(CO)(DMF)(PPh3)2] (1) has already been
identified by James and Co-workers [5] the method employed for the
synthesis of (1) still uses CO (1 atm) as source of the carbonyl ligand, and
the complex was not crystallographically characterized. In fact in this paper
it is assumed that the CO ligand is product of the addition of the CO gas and
not from the activation of the DMF.
*
Corresponding author. Tel.: þ52-555-622-4514; fax: þ52-555-616-
2217.
E-mail address: damor@servidor.unam.mx (D. Morales-Morales).
0022-2860/$ - see front matter q 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2003.11.003

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V. Gomez-Benıtez et al. / Journal of Molecular Structure 689 (2004) 137–141
138
2. Experimental
2.1. Materials and methods
Table 1
Summary of crystal structure data for compound [RuCl2(CO)(DMF)(PPh3)2] (1)
Empirical formula
C40H37Cl2NO2P2Ru
Unless stated otherwise, all reactions were carried out
under an atmosphere of dinitrogen using conventional
Schlenk glassware. The IR spectra were recorded on a
Nicolet-Magna 750 FT-IR spectrometer as nujol mulls.
The 1H and 31P{1H} NMR spectra were recorded on a JEOL
GX300 spectrometer. Chemical shifts are reported in ppm
down field of TMS using the solvent (CDCl3, d ¼ 7:27) as
internal standard. 31P{1H} NMR spectra were recorded with
complete proton decoupling and are reported in ppm using
85% H3PO4 as external standard. Elemental analyses were
determined on a Perkin-Elmer 240. Positive-ion FAB mass
spectra were recorded on a JEOL JMS-SX102A mass
spectrometer operated at an accelerating voltage of 10 Kv.
Samples were desorbed from a nitrobenzyl alcohol (NOBA)
matrix using 3 KeV xenon atoms. Mass measurements in
FAB are performed at a resolution of 3000 using magnetic
field scans and the matrix ions as the reference material or,
alternatively, by electric field scans with the sample peak
bracketed by two (polyethylene glycol or cesium iodide)
reference ions. The N,N0-dimethylformamide (DMF) was
purchased from Aldrich Chemical Co. and used without
further purification. The complex [RuCl2(PPh3)3] [7] was
prepared according to published procedures.
Formula weight
Temperature
797.62
291(2) K
˚
Wavelength
0.71073 A
Triclinic
P 2 1
Crystal system
Space group
˚
Unit cell dimensions
a ¼ 11.7834(6) A, a ¼ 70.810(1)8
˚
b ¼ 12.7571(7) A, b ¼ 86.480(1)8
˚
c ¼ 13.3405(7) A, g ¼ 75.007(1)8
3
˚
Volume
1828.8(2) A
Z
2
Density (calculated)
Absorption coefficient
Fð000Þ
1.448 g/cm3
0.698 mm21
816
Crystal size
0.20 £ 0.14 £ 0.10 mm
1.75–25.008
u range for data
collection
Index ranges
213 # h # 14; 215 # k # 15; 215 # l # 15
15088
Reflections collected
Independent reflections
Absorption correction
Refinement method
Data/restraints/
parameters
6424 ½RðintÞ ¼ 0:0379ꢀ
None
Full-matrix least-squares on F2
6424/0/435
Goodness-of-fit on F2
Final R indices
½I . 2sðIÞꢀ
0.949a
R1 ¼ 0:0328; wR2 ¼ 0:0534a
R indices (all data)
Largest diff. peak
and hole
R1 ¼ 0:0458; wR2 ¼ 0:0551b
23
˚
0.622 and 20.378 e A
2.2. Synthesis of [RuCl2(CO)(DMF)(PPh3)2] (1)
a
2
2 2
S ¼ ½wðFoÞ 2 ðFcÞ Þ =ðn 2 pÞꢀ1=2 where n ¼ number of reflections and
p ¼ total number of parameters.
A solution [RuCl2(PPh3)3] (50 mg, 0.052 mmol) in
DMF (30 cm3) was set to reflux for 2.0 h. After the
prescribed time the resulting solution was evaporated in a
rotovapor and the yellow residue recrystallized from
CH2Cl2/Hexane to yield a microcrystalline yellow powder
of 1. Yield 39 mg (93%).
b
2
2
2
2 1=2
R1 ¼ lFo 2 Fcl=lFol; wR2 ¼ ½wððFoÞ 2 ðFcÞ Þ =wðFoÞ ꢀ
:
using SHELXS-97 [8] program. The remaining atoms were
located via a few cycles of least squares refinements and
difference Fourier maps, using the space group P 2 1;
with Z ¼ 2: Hydrogen atoms were input at calculated
positions, and allowed to ride on the atoms to which they are
attached. Thermal parameters were refined for hydrogen
2.3. Data Collection and refinement for
[RuCl2(CO)(DMF)(PPh3)2] (1)
˚
atoms on the phenyl groups using a Ueq ¼ 1.2 A to precedent
atom. The final cycle of refinement was carried out on all
non-zero data using SHELXL-97 [9] and anisotropic thermal
parameters for all non-hydrogen atoms. The details of the
structure determination are given in Table 1 and selected bond
A crystalline yellow prism of [RuCl2(CO)(DMF)(PPh3)2],
grown from a DMF saturated solution of 1 was glued to a glass
fiber. The X-ray intensity data were measured at 291 K on a
Bruker SMART APEX CCD-based X-ray diffractometer
system equipped with a Mo-target X-ray tube (l ¼
˚
lengths (A) and angles (8) in Table 2. The numbering of the
atoms is shown in Fig. 1 (ORTEP) [10].
˚
0.71073 A). The detector was placed at a distance of
4.837 cm. from the crystal. A total of 1800 frames were
collectedwithascanwidthof0.38 in v andanexposuretimeof
10 s/frame. The frames were integrated with the Bruker
SAINT software package using a narrow-frame integration
algorithm. The integration of the data using a triclinic unit cell
yielded a total of 15088 reflections to a maximum 2u angle of
3. Results and discussion
3.1. Synthesis of [RuCl2(CO)(DMF)(PPh3)2] (1)
˚
50.008 (0.93 A resolution), of which 6424 were independent
By setting to reflux a solution of [RuCl2(PPh3)3] in DMF
for 2.0 h. the product [RuCl2(CO)(DMF)(PPh3)2] (1) can be
isolated as a yellow microcrystalline powder in quantitative
yield. Infrared analysis of a sample of 1 affords a spectrum
(Rint ¼ 3:79%; Rsig ¼ 6:06%) and 4401 were greater than
2sðF2Þ: Analysis of the data showed negligible decay during
data collection. The structure was solved by Patterson method

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V. Gomez-Benıtez et al. / Journal of Molecular Structure 689 (2004) 137–141
139
Table 2
which exhibits two distinctive bands for the two different
types of carbonyl present in the molecule, one at
1917.6 cm21 due to the presence of the CO ligand and the
other at 1639.4 cm21 corresponding to the CO moiety
present in the DMF molecule coordinated to the ruthenium
Selected Bond lengths and angles for [RuCl2(CO)(DMF)(PPh3)2] (1)
˚
Bond lengths (A)
Angles (8)
Ru(1)–C(37)
Ru(1)–O(2)
Ru(1)–P(1)
Ru(1)–Cl(2)
Ru(1)–P(2)
Ru(1)–Cl(1)
O(1)–C(37)
O(2)–C(38)
N(1)–C(38)
N(1)–C(39)
N(1)–C(40)
C(38)–H(38)
1.805(3)
2.1669(18)
2.3847(8)
2.3871(7)
2.3896(8)
2.4025(8)
1.145(3)
1.226(3)
1.313(3)
1.431(3)
1.447(4)
0.9300
C(37)–Ru(1)–O(2)
C(37)–Ru(1)–P(1)
O(2)–Ru(1)–P(1)
C(37)–Ru(1)–Cl(2)
O(2)–Ru(1)–Cl(2)
P(1)–Ru(1)–Cl(2)
C(37)–Ru(1)–P(2)
O(2)–Ru(1)–P(2)
P(1)–Ru(1)–P(2)
Cl(2)–Ru(1)–P(2)
C(37)–Ru(1)–Cl(1)
O(2)–Ru(1)–Cl(1)
P(1)–Ru(1)–Cl(1)
Cl(2)–Ru(1)–Cl(1)
P(2)–Ru(1)–Cl(1)
C(35)–C(36)–H(36)
O(1)–C(37)–Ru(1)
C(38)–O(2)–Ru(1)
C(38)–N(1)–C(39)
C(38)–N(1)–C(40)
C(39)–N(1)–C(40)
O(2)–C(38)–N(1)
O(2)–C(38)–H(38)
175.40(11)
89.40(9)
89.49(5)
98.74(9)
85.70(5)
88.61(3)
90.66(9)
90.65(5)
177.34(3)
88.75(3)
94.83(9)
80.74(5)
91.87(3)
166.43(3)
90.78(3)
119.7(5)
178.8(3)
134.1(2)
120.7(3)
123.1(3)
116.2(2)
123.8(3)
118.1
1
center. Analysis by H NMR spectroscopy offers further
information, the spectra shows signals in the region of d
7.25–7.60 ppm due to the presence of the aromatic rings of
the triphenylphosphine ligands in the complex, additionally
two singlets can be clearly appreciated at d 2.87 and
2.77 ppm due to the presence of the methyl groups at the
amide moiety in the coordinated DMF, the fact that we are
observing two different signals for the methyl groups
suggest both methyl groups to be in to a slightly different
magnetic environments. A signal due to the proton of the
DMF is observed at d 7.60 ppm. The 31P NMR spectrum of
1 shows a single signal at d 34.5 ppm which is in agreement
with the proposed structure where the two phosphorus
centers are magnetically equivalent by being arranged in a
mutually trans conformation. The FABþ-MS spectrum
shows a peak corresponding to the [M-DMF-Cl]þat 689 m=z
with the adequate isotope distribution, [11]. Other important
fragments can be observed at 654 and at 625 m=z due to the
consecutive loss of the remaining Cl and CO ligands,
respectively.
3.2. The crystal structure of [RuCl2(CO)(DMF)(PPh3)2] (1)
Crystals of complex 1 were obtained by slow
evaporation from a saturated solution of 1 in DMF
as yellow prisms The X-Ray crystal structure analysis
shows the Ru center to be in a slightly distorted
octahedral environment (Fig. 1). The coordination sphere
of 1 is constituted by two mutually trans chloride ligands in
the equatorial plane, completing this plane a carbonyl
ligand having a trans O-coordinated DMF molecule.
The octahedron is completed by two mutually trans PPh3
ligands in the axial positions, conferring a ‘dumbbell’ like
shape to the molecule with large ends due to the PPh3 ligands
and a narrow waist occupied by the small equatorial
substituents. The Ru–Cl lengths Ru(1)–Cl(1) 2.4025(8)
˚
and Ru(1)–Cl(2) 2.3871(7) A are smaller incomparison with
those found in [RuCl2(H2)(PCy3)2(h 1-OyC(NMe2)Me)]
˚
[12] [Ru–Cl(1) 2.423(4) and Ru–Cl(2) 2.428(6) A]
and [RuCl2(CO)(4-pic)(PPh3)2] 4-pic ¼ 4-picoline [13]
˚
[Ru–Cl(1) 2.413(4) and Ru–Cl(2) 2.421(4) A].
˚
The Ru–CO [Ru(1)–C(37) 1.805(3) A] distance is also
considerable shorter in comparison with those observed for
other Ru-carbonyl complexes like [RuCl2(CO)2(BzPPh2)2]
˚
[13] [Ru–C(1) 1.869(7) A], this can be rationalize in terms of
the difference in trans influence exerted by the different
ligands, since in [RuCl2(CO)2(BzPPh2)2] [13] the Cl trans
influence is stronger than that exerted by the DMF ligand in 1.
The Ru–P lengths [Ru(1)–P(1) 2.3847(8) and Ru(1)–P(2)
˚
2.3896(8) A] are also slightly shorter in comparison with
those found in [RuCl2(CO)(4-pic)(PPh3)2] [13] [Ru–P(1)
Fig. 1. The molecular structure of [RuCl2(CO)(DMF)(PPh3)2] indicating
the numbering of the atoms. Hydrogen atoms are omitted for clarity.
The thermal ellipsoids have been drawn at 50% probability.

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V. Gomez-Benıtez et al. / Journal of Molecular Structure 689 (2004) 137–141
140
Fig. 2. The molecular structure of [RuCl2(CO)(DMF)(PPh3)2] showing the intermolecular Cl· · ·H interaction. Hydrogen atoms on the aromatic rings have been
omitted for clarity. The thermal ellipsoids have been drawn at 50% probability.
˚
2.406(4) and Ru–P(2) 2.404(4) A]; [RuCl2(CO)2(BzPPh2)2]
Acknowledgements
˚
[14] [Ru–P(1) 2.410(2) and Ru–P(2) 2.410(2) A] and
[Ru(O2CNiPr2)2(CO)2(PPh3)2] [15] [Ru–P(1) 2.402(2) and
˚
Ru–P(2) 2.411(2) A]. The Ru(1)–O(2) 2.1669(18) bond
V. G.-B. and J O.-M would like to thank CONACYT for
financial support. We would like to thank Chem. Eng. Luis
´
Velasco Ibarra, M. Sc. Francisco Javier Perez Flores and
distance is within the expected value. The main distortion
from the octahedral geometry is given by the chloride
atoms which bend away from the carbonyl group
[Cl(1)–Ru(1)–Cl(2)], this causing all other angles
[C(37)–Ru(1)–Cl(2) 98.74(9)8; O(2)–Ru(1)–Cl(2)
85.70(5)8; C(37)–Ru(1)–Cl(1) 94.83(9)8; O(2)–
Ru(1)–Cl(1) 80.74(5)8] in the equator of the molecule to
be different from 908. The angle C(38)–O(2)–Ru(1)
134.1(2)8 is bigger in comparison with that observed in the
carbamoyl complex [Ru(H)2Cl(h 2-C(O)NMe2)(PiPr3)2],
[16] clearly indicating the coordination of the DMF in 1 to
be O-h 1. It is noteworthy that apparently, the solid state
structure is stabilized by chlorine–hydrogen intermolecular
interactions (Fig. 2).
´
QFB. Ma del Rocıo Patin˜o for their invaluable help in the
running of the FAB-Mass and Infrared Spectra. The support
of this research by CONACYT (J41206-Q) is gratefully
acknowledged.
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