Polypyrazolylmethane complexes of ruthenium

Article abstract of DOI:10.1039/b103939n

A series of ruthenium(II) complexes with the pyrazolyl alkane ligands tris(1-pyrazolyl)methane 1 (TPM) and bis(1-pyrazolyl)methane 2 (BPM) have been synthesized and characterised. The complex [RuCl(PPh₃)₂(TPM)]⁺X (X = Cl 3a or BF₄ 3b) was formed by the reaction of TPM with RuCl₂(PPh₃)₃ and [Ru(CO)H(PPh₃)(TPM)]⁺X (X = Cl 4a or BF₄ 4b) by the reaction of TPM with Ru(CO)ClH(PPh₃)₃. The complexes [RuCl(PPh₃)(BPM)₂]⁺Cl^- 5 and [(BPM)(Ph₃P)Ru(μ-Cl)₃Ru(PPh₃)(BPM)]⁺ Cl^- 6 were synthesized by the reaction of BPM with RuCl₂(PPh₃)₃. Complexes 3-6 were characterised by multinuclear NMR spectroscopy, and 3a and 6 by X-ray crystallography. [RuCl(PPh₃)₂(TPM)]⁺Cl^- exhibits dynamic behaviour at low temperature and this is attributed to restricted rotation of the PPh₃ groups about the M-P bond.

Full text of DOI:10.1039/b103939n

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Polypyrazolylmethane complexes of ruthenium†
Leslie D. Field,*a Barbara A. Messerle,*b Linnea Soler,a Irmi E. Buysa and
Trevor W. Hambleya
a School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia.
E-mail: L.Field@chem.usyd.edu.au
b School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
Received 11th October 2000, Accepted 2nd May 2001
First published as an Advance Article on the web 12th June 2001
A series of ruthenium() complexes with the pyrazolyl alkane ligands tris(1-pyrazolyl)methane 1 (TPM) and
bis(1-pyrazolyl)methane 2 (BPM) have been synthesized and characterised. The complex [RuCl(PPh3)2(TPM)]ϩX
(X = Cl 3a or BF4 3b) was formed by the reaction of TPM with RuCl2(PPh3)3 and [Ru(CO)H(PPh3)(TPM)]ϩX
(X = Cl 4a or BF4 4b) by the reaction of TPM with Ru(CO)ClH(PPh3)3. The complexes [RuCl(PPh3)(BPM)2]ϩClϪ
5 and (BPM)(Ph3P)Ru(µ-Cl)3Ru(PPh3)(BPM)]ϩClϪ 6 were synthesized by the reaction of BPM with RuCl2(PPh3)3.
Complexes 3–6 were characterised by multinuclear NMR spectroscopy, and 3a and 6 by X-ray crystallography.
[RuCl(PPh3)2(TPM)]ϩClϪ exhibits dynamic behaviour at low temperature and this is attributed to restricted rotation
of the PPh3 groups about the M–P bond.
complex [RuCl(PPh3)(BPM)2]ϩClϪ 5 and a bimetallic complex
Introduction
[(BPM)(Ph3P)Ru(µ-Cl)3Ru(PPh3)(BPM)]ϩClϪ 6 were formed
Transition metal complexes with ligand systems containing
by the reaction of BPM 2 with RuCl2(PPh3)3. Complexes 3–6
were characterised by multinuclear NMR spectroscopy and 3a
and 6 also by X-ray diffraction.
N-donors have been used successfully to promote the trans-
formation of organic compounds,1 and also to act as structural
mimics of metalloenzymes.2 Ruthenium complexes containing
bidentate N-donor ligands with sp2 hybridised nitrogen atoms
such as 2,2Ј-bipyridyl,3 1,10-phenanthroline,3 and bis(pyrazol-
1-yl)methane4 have recently found use in catalytic hydrogen-
ation. N-Donor poly(1-pyrazolyl)borate ligands are also
well established as versatile polydentate N-donors and tris-
(1-pyrazolyl)borate complexes of Ir,5 Rh6 and Re7 are suf-
ficiently reactive species to undergo additions to C–H bonds in
alkanes, alkenes and aromatic hydrocarbons. Polypyrazolyl-
methanes, such as tris(1-pyrazolyl)methane 1 (TPM)8 and
bis(1-pyrazolyl)methane 2 (BPM),8 are neutral ligands which
Results and discussion
Complex [RuCl(PPh3)2(TPM)]ϩClϪ 3a was synthesized by dis-
placement of triphenylphosphine and chloride from RuCl2-
(PPh3)3 with TPM (Scheme 1). The reaction proceeded quickly
Scheme 1
are isosteric and isoelectronic with polypyrazolylborates.
Complexes of Ru,9 Rh and Ir,10 Pt,11 Pd,12 Fe,13 Cd and Hg,14
V,15 Mo and W,16 and Al17 of poly(1-pyrazolyl)methane ligands
have been synthesized and studied. A limited number of poly-
(1-pyrazolyl)methane complexes of metals of the iron triad
in good yield to give 3a as an air-stable yellow crystalline solid.
Crystals of the complex were also formed with the tetrafluoro-
borate counter ion by slowly cooling a warm ethanolic solution
Ϫ
containing equimolar quantities of 3 and NaϩBF4 to yield
yellow-orange crystals of [RuCl(PPh3
) (TPM)]ϩBF Ϫ 3b.
have been reported,9 and these include [Ru(BPM)(PMe3)2-
2
4
Ϫ 18
(CO)(COMe)]ϩBPh4 ,
[Ru(TPM)(OH2)3][p-CH3C6H4SO3]2ؒ
Crystal structure of [RuCl(PPh3)2(TPM)]ClؒPPh3ؒ
2CH3CH2OH 3a
1.5H2O19 and [Ru(TPM)(COD)Cl]ϩClϪ.20
In this paper we report the synthesis and characterisation
of ruthenium() complexes containing the bidentate and tri-
dentate (1-pyrazolyl)methane ligands 1 and 2. The cation
[RuCl(PPh3)2(TPM)]ϩ 3 was formed by the reaction of TPM 1
with RuCl2(PPh3)3 21 and the cation [Ru(CO)H(PPh3)(TPM)]ϩ 4
by the reaction of TPM 1 with Ru(CO)ClH(PPh3)3.22 The
[RuCl(PPh3)2(TPM)]ϩClϪ 3a forms air-stable yellow prisms as
the ethanol solvate with TPP (PPh3) cocrystallised when crystal-
lised from an ethanolic solution. A perspective view of the
cation 3a is shown in Fig. 1 and selected bond lengths and
angles for the inner coordination sphere are listed in the elec-
tronic supplementary information (ESI). The geometry about
the ruthenium centre is essentially octahedral with the three
nitrogen atoms of the pyrazolyl groups, a chlorine atom and the
phosphorus atoms of the two triphenylphosphine ligands as
† Electronic supplementary information (ESI) available: selected bond
lengths and angles for complexes 3a and 6, NMR data for complexes
3–5. See http://www.rsc.org/suppdata/dt/b1/b103939n/
DOI: 10.1039/b103939n
J. Chem. Soc., Dalton Trans., 2001, 1959–1965
This journal is © The Royal Society of Chemistry 2001
1959

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Table 1 Comparison of selected bond lengths (Å) and bond angles (deg) in compounds related to [RuCl(PPh3)2(TPM)]ϩClϪ 3aa
[RuCl(PPh3)2-
(TPM)]ϩClϪ
RuCl(PPh3)2-
(TPB)24
RuCl(PPh3)2-
[RuCl(PPh3)2((mim)3-
COH)]ϩClϪ 26
Ru(TPM)-
Atoms
(η-C5H5)25
(OH2)3]2ϩ 19
Ru–Cl(1)
Ru–P(1)
Ru–P(2)
Ru–N(1)
Ru–N(2)
Ru–N(3)
2.402(2)
2.351(2)
2.374(2)
2.117(6)
2.126(6)
2.083(6)
2.409(3)
2.349(3)
2.332(3)
2.104(7)
2.126(7)
2.085(8)
2.453(2)
2.337(1)
2.335(1)
—
—
—
2.420(1)
2.344(1)
2.371(1)
2.123(3)
2.137(4)
2.062(3)
2.121(1)Ru-O
2.134(1)Ru-O
2.139(1)Ru-O
2.008(2)
2.028(2)
2.006(2)
P(1)–Ru–P(2)
P(1)–Ru–Cl(1)
P(2)–Ru–Cl(1)
N(1)–Ru–N(5)
N(3)–Ru–N(5)
N(1)–Ru–N(3)
103.9(1)
89.9(1)
94.8(1)
78.4(2)
86.4(2)
87.2(2)
101.9(1)
96.0(1)
89.0(1)
79.9(3)
87.7(3)
87.3(3)
103.99(4)
89.05(3)
90.41(4)
—
—
—
102.4(0)
91.6(0)
95.9(0)
79.4(1)
86.0(1)
85.7(1)
89.34(7)O-Ru-O
89.89(8)O-Ru-O
88.15(7)O-Ru-O
86.49(8)
87.46(8)
87.09(8)
a Atoms from references have been renumbered to a common numbering scheme.
(78.4(2), 86.4(2), 87.2(2)Њ) being smaller than the ideal 90Њ
(Table 1). Diminished N–Ru–N bond angles have also been
noted in related complexes including [Ru(TPM)(OH2)3]-
[p-CH3C6H4SO3]2ؒ1.5H2O19 (86.49(8), 87.46(8), 87.09(9)Њ),
[Ru(TPM)(COD)Cl]ϩClϪ 20 (86.6(2), 83.9(2), 79.9(2)Њ), and
[RuCl(PPh3)2((mim)3COH)]ϩClϪ 26 (79.4(1), 85.7(1), 86.0(1)Њ)
(mim = N-methylimidazolyl).
In complex 3a both Ru–P bond lengths (2.374(2), 2.351(2) Å)
are shorter than the Ru–Cl bond (2.402(2) Å). Similar Ru–Cl
bond lengths are found in RuCl(PPh3)2(TPB)24 (2.409(3) Å),
[Ru(TPM)(COD)Cl]ϩClϪ 20 (2.424(2) Å), and RuCl(PPh3)2-
(η-C5H5)25 (2.453(2) Å) (Table 1). Similar Ru–P bond lengths
are found in RuCl(PPh3)2(TPB)24 (2.332(3), 2.349(3) Å), and
RuCl(PPh3)2(η-C5H5)25 (2.337(1), 2.335(1) Å) (Table 1). Both
Ru–N bond lengths trans to the phosphorus ligands are longer
(2.117(6), 2.126(6) Å) than Ru–N bond lengths trans to the
chloro ligand (2.083(6) Å). The equivalent RuCl(PPh3)2(TPB)24
and [RuCl(PPh3)2((mim)3COH)]ϩClϪ 26 complexes display the
same lengthening of the Ru–N bonds.
Fig.
1
An ORTEP23 plot of [RuCl(PPh3)2(TPM)]ClؒPPh3ؒ
2CH3CH2OH 3a with numbering. The molecule is oriented with the
Ru–apical carbon axis vertical. Only the P atoms of the two triphenyl-
phosphine ligands are shown.
NMR Studies of [RuCl(PPh3)2(TPM)]؉Cl؊ 3a
By NMR at room temperature the two triphenylphosphine
ligands of 3 are equivalent, as are the two pyrazolyl rings trans
to the triphenylphosphine ligands. Only one 31P resonance is
observed, and in the proton spectrum at room temperature two
sets of resonances are observed for the TPM ligand protons,
with intensities in the ratio of 2 : 1 (rings A and B, Fig. 2).
However, at 185 K (600 MHz), the phosphorus resonance is
clearly split into two signals, and the proton resonances of the
TPM ligand split to give three sets of resonances indicating
three non-equivalent pyrazolyl rings. The proton resonances of
the phenyl groups of the PPh3 groups also show some broaden-
ing near 185 K. The dynamic behaviour is consistent with a
slowing of the rotation of the triphenylphosphine groups about
the M–P bonds. The motion of the triphenylphosphine ligands
must freeze to conformations where the PPh3 groups are non-
equivalent, and this probably involves interleaving or “cog-
wheeling” of the phenyl substituents on the phosphorus
donors27 (Fig. 2).
ligating atoms. There is some distortion from ideal octahedral
geometry about the metal centre, and this is probably the result
of the constraints imposed on the three pyrazolyl nitrogen
donor atoms by the TPM architecture. The pyrazolyl rings
within the TPM ligand are essentially planar.
The steric bulk of the two triphenylphosphine ligands causes
the P–Ru–P bond angle (103.9Њ) to exceed the expected 90Њ of
perfect octahedral symmetry. In addition, the pyrazolyl rings
located between a triphenylphosphine ligand and chlorine are
displaced away from the triphenylphosphine ligands, with the
angle between the plane containing the Ru atom and N donors
and the plane of the pyrazole ring less than 180Њ. Both P–Ru–Cl
bond angles (89.9(1), 94.8(1)Њ) are smaller than the P–Ru–P
angle. Comparison with similar compounds RuCl(PPh3)2-
(TPB)24 [TPB = hydrotris(pyrazolyl)borate] and RuCl(PPh3)2-
(η-C5H5)25 reveals the same distortion with large P–Ru–P
angles (ca. 102Њ) and similar P–Ru–Cl angles (ca. 89 and 95Њ
respectively) (Table 1). The other source of distortion from
perfect octahedral symmetry is likely to arise from constraints
imposed by the tridentate ligand, with the N–Ru–N angles
The kinetics of interconversion between the two conform-
ations, observed at low temperature, was calculated by line shape
analysis of the two exchanging phosphorus resonances and the
1960
J. Chem. Soc., Dalton Trans., 2001, 1959–1965

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Fig. 3 Structure of [RuCl(PPh3)(BPM)2]ϩClϪ 5 indicating the strong
NOESY interactions observed.
Fig. 2 Restricted rotation of bulky triphenylphosphine ligands in
cis-coordination sites in [RuCl(PPh3)2(TPM)]ϩ 3.
rate of exchange is approximately 1150 sϪ1 at 205 K. Restricted
rotation is not unexpected with two bulky triphenylphosphine
substituents in adjacent coordination sites.
[Ru(CO)H(PPh3)(TPM)]؉Cl؊ 4a
Ϫ
Complex [Ru(CO)H(PPh3)(TPM)]ϩXϪ (XϪ = ClϪ, 4a; BF4 , 4b
Scheme 3
was prepared by the reaction of TPM with Ru(CO)ClH(PPh3)3
(Scheme 2). The complex 4a was obtained as an air-stable
1
phosphine and the H NMR spectrum contains peaks due to
one bound triphenylphosphine and two inequivalent BPM
ligands, indicating that the triphenylphosphine and chloride
ligands are mutually cis. The neutral bis(1-pyrazolyl)borate
29
(BPB) analogue Ru(BPB)2(PPh3)2 possesses a similar geom-
etry with the two PPh3 ligands mutually cis.
Resonances in the 1H NMR spectrum of [RuCl(PPh3)-
1
(BPM)2]ϩClϪ 5 were assigned by a combination of H COSY
1
and H NOESY NMR experiments. The NOESY spectrum
demonstrates that the two BPM ligands are significantly
puckered; only one of the two methylene protons of each ligand
interacts with the closest protons of the pyrazolyl rings. There is
also a strong NOESY interaction between the protons of the
pyrazolyl rings and the protons of the triphenylphosphine
ligand (Fig. 3). Boat geometries have been observed for the
ligands of similar bis(1-pyrazolyl)methane complexes involving
ruthenium,20 rhodium,10a and palladium.30
Scheme 2
cream powder and 4b by exchange of the counter ion by treat-
ment with a methanolic solution of NaBF4.
The 1H NMR spectrum of [Ru(CO)H(PPh3)(TPM)]ϩ
4
Bis[bis(1-pyrazolyl)methane]tri-ꢀ-chloro-bis(triphenylphosphine)-
diruthenium(II) chloride [(BPM)(Ph3P)Ru(ꢀ-Cl)3Ru(PPh3)-
(BPM)]؉Cl؊ 6
contained a doublet due to the phosphorus-coupled metal
hydride as well as nine inequivalent pyrazolyl protons. The
1
stereospecific assignment of the H spectra was achieved using
a combination of 1H NOESY and 1H COSY experiments. The
two pyrazolyl rings closest to the metal bound hydride exhibit
strong NOESY crosspeaks between the hydride resonances and
Addition of BPM to a dichloromethane solution of RuCl2-
(PPh3)3, in a 2 : 1 ratio, formed the highly insoluble triply
bridged dinuclear product [(BPM)(Ph3P)Ru(µ-Cl)3Ru(PPh3)-
(BPM)]ϩClϪ 6. The air stable deep red crystals were character-
the protons of two of the pyrazolyl rings (labelled HA3 and HB
3
3
in 4, Scheme 2). The NOESY crosspeaks {hydride⇔HA }
and {hydride⇔HB } are approximately equal in intensity,
3
which indicates that the hydride is located approximately sym-
metrically between the two pyrazolyl rings, consistent with the
octahedral geometry of the system. Additional interactions
between the phenyl protons of the triphenylphosphine ligand
and the protons of the pyrazolyl rings allowed the stereo-
chemistry about the metal centre fully to be assigned. The infra-
red spectrum of 4a contained a band at 1934 cmϪ1 attributed to
the CO stretching mode.28
1
ised by H NMR and single crystal X-ray diffraction analysis.
Analogues of 4, [Ru(CO)(H)(TPB)(PPh3)]28 and [Ru(PPh3)-
(CO)H((mim)3COH)]ϩClϪ,26 have also been reported.
The mononuclear species [RuCl(PPh3)(BPM)2]ϩClϪ 5 was
also isolated from the reaction mixture. Investigation of the
dinuclear species 6 by 1H NMR spectroscopy reveals that
the two BPM ligands are chemically equivalent and the two
pyrazolyl rings of each of ligand are chemically non-equivalent.
Bis[bis(1-pyrazolyl)methane]chloro(triphenylphosphine)-
ruthenium(II) chloride [RuCl(PPh3)(BPM)2]؉Cl؊ 5
The air-stable glassy green solid [RuCl(PPh3)(BPM)2]ϩClϪ
5
Crystal structure of [(BPM)(Ph3P)Ru(ꢀ-Cl)3Ru(PPh3)-
(BPM)]؉Cl؊ 6
was formed by the addition of BPM to a THF solution of
RuCl2(PPh3)3 in a 1 : 2 ratio (Scheme 3). The structure of
the complex is evident from its NMR spectra. The 31P NMR
spectrum contains one resonance due to bound triphenyl-
The compound was crystallised as an air-stable red solid. It has
pseudo twofold symmetry and the two ruthenium atoms, which
J. Chem. Soc., Dalton Trans., 2001, 1959–1965
1961

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formations. The two metal centres in the dinuclear complex 6
are too far apart to show any significant bonding interaction.
Experimental
The synthesis and manipulation of all ligands and metal com-
plexes were performed under an inert atmosphere of argon or
nitrogen unless otherwise stated using a Vacuum Atmosphere
dry box or standard Schlenk techniques.
1H, 31P, and 13C NMR spectra were recorded on Bruker
AMX400, AMX600 or AC200 spectrometers. 31P NMR spectra
were acquired with broadband 1H decoupling. 1H NMR chem-
ical shifts are referenced to residual solvent resonances or using
TMS as an internal reference, 31P NMR to external, neat tri-
methyl phosphite, taken as δ 140.85 at the temperature quoted.
Uncertainties in the chemical shifts are typically 0.005 ppm
for 1H and 0.05 ppm for 31P NMR. Coupling constants (J) are
given in Hz. Spectra were acquired at 300 K, unless otherwise
stated. DQF (double quantum filtered) COSY34 and NOESY35
spectra were acquired with 31P decoupling in both ω1 and ω2.
Typically 640 slices in ω1 of 2048 points in ω2 were acquired,
with a total acquisition time of approximately 8 hours. For the
NOESY experiments mixing times, τm, of 1.6 seconds were
used. Total acquisition times were typically 8 hours.
Mass spectra of the ligands were recorded on an AEI model
MS902 double focussing mass spectrometer with an accelerat-
ing voltage of 8000 V and using Electron Impact (EI) ionisation
with an electron energy of 70 eV. The sample was inserted
through a solid direct insertion probe with a source temperature
of 200 ЊC. FAB mass spectra were acquired of the metal
complexes using a Finnigan MAT TSQ 46 mass spectrometer
(San Jose, CA, USA) which is fitted with an Electron Impact/
Fig. 4 Structure of [(BPM)(Ph3P)Ru(µ-Cl)3Ru(PPh3)(BPM)]ϩClϪ
indicating the atom numbering scheme. The molecule is oriented with
the Ru–apical carbon axis horizontal. For clarity, only the P and three
attached C atoms are shown for the triphenylphosphine ligands.
6
lack perfect octahedral coordination, are linked by three bridg-
ing chlorine atoms. A perspective view of 6 is shown in Fig. 4,
and the bond lengths and angles for the inner coordination
sphere are listed in the electronic supplementary information.
The distortion from octahedral geometry at the two metal
centres is seen in the small Ru–Cl–Ru bond angles (80–84Њ) and
the small Cl–Ru–Cl bond angles (80–84Њ). The N–Ru–N bond
angles comply with octahedral restraints, partly due to the
structural properties of the ligand itself. However, the P–Ru–N
bond angles (99.5(2), 92.3(2) and 99.7(2), 95.1(2)Њ) exceed the
value expected for perfect octahedral symmetry, which is likely
to be due to steric crowding by the triphenylphosphine ligand.
The pyrazolyl rings are essentially planar and the six-membered
metallocycle Ru(N–N)2C units of the bound BPM ligands
adopt pseudo-boat conformations. The dihedral angles
between the planes of the pyrazolyl subunits (44.04 and 47.48Њ)
are similar to the values found for the structurally similar
Rh(N–N)2C metallocycle of the [Rh(COD)(BPM)]ϩClO4
complex (47.1Њ).10a
Chemical Ionisation (EI/CI) source and
a Fast Atom
Bombardment (FAB) 8 kV potential gun (ION TECH, Fast
Atom Gun, Middlesex, UK). The FAB mass spectra were
acquired using a magic bullet matrix [a 5 : 1 (w/w) mixture of
dithiothreitol (DTT) (98%) and dithioerythritol (DTE)(98%)],36
a source temperature of 50 ЊC, and a manifold temperature of
80 ЊC. Both the CI and EI mass spectra were acquired using a
source temperature of 140 ЊC and a manifold temperature of
115 ЊC. The spectra are quoted in the form x(y) where x is the
mass to charge ratio and y the percentage abundance relative to
the base peak.
The relatively large Ru ؒ ؒ ؒ Ru separation of 3.208 Å indicates
that there is no significant metal–metal interaction.31 Similar
dinuclear ruthenium complexes containing a tri-µ-chloro bridge
and triphenylphosphine ligands with a confacial bioctahedral
structure have been reported: (Bun P)2ClRu(µ-Cl)3Ru(PBun )2-
3
3
Infrared spectra (cmϪ1) were recorded either on a Perkin-
Elmer 1600 series FTIR instrument using KBr disks or by using
diffuse reflectance techniques on a Bio-Rad FTS-40 using
powdered KBr as the matrix. Melting points were recorded on a
Reichert heating stage and are uncorrected.
Cl,32 (Et2PhP)3Ru(µ-Cl)3Ru(PEt2Ph)2Cl,31 and [(Me2PhP)3-
Ru(µ-Cl)3Ru(PMe2Ph)3]ϩClϪ.33 The Ru–µ-Cl bonds in 6 trans
to the triphenylphosphine ligands are longer than the other
Ru–µ-Cl bonds. Related dinuclear complexes31–33 also exhibit
lengthening of the Ru–Cl bonds trans to the Ru–P bonds,
compression of the Cl–Ru–Cl and Ru–Cl–Ru bond angles,
and consequent distortion of the bioctahedral symmetry.
Tetrahydrofuran (THF), benzene, toluene, and hexane were
pre-dried over sodium and distilled under nitrogen from
sodium–benzophenone over sodium wire immediately prior to
use. Absolute ethanol and methanol were refluxed with mag-
nesium turnings and iodine and distilled under an atmosphere
of nitrogen. Acetone was dried over and distilled from
anhydrous calcium sulfate. Dichloromethane (DCM) was
washed sequentially with concentrated H2SO4, water, 5%
K2CO3 solution, water and distilled from CaCl2. All solvents
used in reactions of air sensitive compounds were deaerated
prior to use by saturation with nitrogen or degassed by four to
five freeze–pump–thaw cycles. All compressed gases were
obtained from Commonwealth Industrial Gases (C.I.G.).
Argon (>99.99%), nitrogen (>99.5%), and hydrogen
(>99.999%) were used as received.
Microanalyses were carried out at the Micro Analysis
Facility in the University of New South Wales and at the
Department of Chemical Engineering in the University of
Sydney.
Pyrazole was obtained from Aldrich and used without
further purification. Tris(1-pyrazolyl)methane (TPM) and
bis(1-pyrazolyl)methane (BPM) were prepared using the
Conclusion
Novel ruthenium complexes containing the TPM and BPM lig-
ands were synthesized and characterised. The complex cation
[RuCl(PPh3)2(TPM)]ϩ 3 has a structure which is analogous
to those of neutral ruthenium complexes containing tris-
(1-pyrazolyl)borate ligands. With two triphenylphosphine
groups in cis coordination sites, it exhibits dynamic behaviour
in solution and this is consistent with restricted rotation about
the Ru–P bonds. The complex [Ru(CO)H(PPh3)(TPM)]ϩ 4 was
prepared by the reaction of TPM with Ru(CO)ClH(PPh3)3 and
the structure and stereochemistry were fully assigned using
NMR experiments.
The complexes [RuCl(PPh3)(BPM)2]ϩClϪ 5 and (BPM)-
(Ph3P)Ru(µ-Cl)3Ru(PPh3)(BPM)]ϩClϪ 6 were synthesized by
reaction of the bidentate ligand BPM 2 with RuCl2(PPh3)3. The
NMR studies of the mononuclear complex 5 showed that the
conformation of the BPM ligands was fixed in solution at room
temperature, and that both BPM ligands were in boat con-
1962
J. Chem. Soc., Dalton Trans., 2001, 1959–1965

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21
3
methods developed by Julia, et al.8 RuCl2(PPh3)3
Ru(CO)ClH(PPh3)3
methods.
and
3JCP 2.2, CPhpara], 130.0 [d, JCP 9.9 Hz, CPhortho], 109.7 [CA4],
22
4 4
were synthesized using literature
109.5 [CC ], 109.3 [CB ], 69.1 [Capical]. Complete NMR data have
been deposited as electronic supplementary information. Mass
spectrum (CI, CH4): m/z 607 (Mϩ, 44%, C29H26N6OPRu), 409
(100, M Ϫ TPMϩCH4).
Preparations
Ϫ
[Ru(CO)(H)(PPh3)(TPM)]ϩBF4 4b.
A mixture of
Chlorobis(triphenylphosphine)[tris(1-pyrazolyl)methane]-
ruthenium(II) chloride 3a and tetrafluoroborate 3b [RuCl-
(PPh3)2(TPM)]؉X (X ؍ Cl 3a or BF4 3b). [RuCl(PPh3)2-
(TPM)]ϩClϪ 3a. A solution of TPM (180 mg, 0.84 mmol) and
RuCl2(PPh3)3 7 (0.79 g, 0.82 mmol) in THF (100 mL) was
stirred under an atmosphere of nitrogen for 90 minutes. The
mixture was filtered and the solvent removed in vacuo to give
the crude product. Recrystallisation from ethanol (40 mL)
Ru(CO)ClH(PPh3)3 (238 mg, 0.25 mmol) and TPM (54 mg,
0.25 mmol) was refluxed vigorously in toluene (25 mL) for 3
hours. The toluene solvent was removed under reduced pressure
and the product taken up in methanol (25 mL) containing
NaBF4 (40 mg, 0.36 mmol). The reaction mixture was stirred
well for 3 hours and the product, [Ru(CO)(H)(PPh3)(TPM)]ϩ-
Ϫ
BF4 4b, isolated by filtration as a pale grey powder (88 mg,
48%), mp decomposes at 225 ЊC (from MeOH). IR νmax
/
cmϪ1(KBr powder): 1984m (Ru–H), 1944vs (CO). Complete
NMR data have been deposited as electronic supplementary
information.
afforded
chlorobis(triphenylphosphine)[tris(1-pyrazolyl)-
methane]ruthenium() chloride 3a as yellow plates (0.40 g,
53%), mp 139–143 ЊC. Found: C, 60.6; H, 4.9; N, 8.8.
C46H40Cl2N6P2Ru requires C, 60.65; H, 4.4; N, 9.2%. IR νmax
/
cmϪ1(KBr disc): 3415b, 3099m, 3056m, 1623w, 1480m, 1433s,
1293s, 1091s, 853m, 797m, 745s, 698s, 614m, 522s, 468m.
δH (400 MHz; solvent MeOD) 9.82 [1H, s, Hapical], 8.61 [1H, d,
Bis[bis(1-pyrazolyl)methane]chloro(triphenylphosphine)-
ruthenium(II) chloride [RuCl(PPh3)(BPM)2]؉Cl؊ 5. A solution
of BPM (170 mg, 1.1 mmol) and RuCl2(PPh3)3 (540 mg, 0.57
mmol) in THF (150 ml) was stirred for 1 hour at room temper-
ature then heated for 30 minutes with stirring. The solvent was
removed in vacuo to yield the crude product as a deep green
residue. The residue was washed with hexane to remove free
PPh3 after which methanol (150 mL) was added. The solution
was heated and stirred fully to dissolve the residue. After 24
hours the solution was filtered to remove the dark yellow crys-
tals from the clear olive-green filtrate. The filtrate was reduced
in vacuo to give the air stable product [RuCl(PPh3)(BPM)2]ϩ-
ClϪ 5 as a clear green glassy residue (0.3 g, ca. 73% based on
unsolvated [RuCl(PPh3)(BPM)2]ϩClϪ 5), mp 188–191 ЊC (from
MeOH). Found: C, 52.3; H, 4.65; N, 14.4. C32H31Cl2N8-
5
3
HB ], 8.49 [2H, d, JHA5-HA4 = 2.8, HA5], 7.55 [6H, m, HPhpara],
7.38 [12H, s(b), HPhortho], 7.35 [12H, m, HPhmeta], 7.12 [2H, d,
3JHA3-HA4 2.1 Hz, HA3], 6.28 [2H, dd, 3JHA4-HA3 = 3JHA4-HA5 = 2.5,
4
HA4], 5.93 [1H, dd, 3JHB4-HB3 = 3JHB4-HB5 = 2.7, HB ], 5.46 [1H, d,
3
3JHB3-HB4 = 2.3 Hz, HB ]. δP{1H}(162 MHz; solvent MeOD) 39.3.
3
δ13C{1H} (150 MHz; solvent MeOD) 152.1 [CB ], 149.6 [CA3],
5
136.6 [CB ], 135.9 [dd, 3JCP 4.4, 4.9, CPhortho], 134.9 [d, 3JCP 40.3,
CPhipso], 134.8 [CA5], 131.5 [s, CPhpara], 129.5 [dd, 3JCP 4.4, 4.9 Hz,
4
CPhmeta], 109.6 [CA4], 109.3 [CB ], 77.6 [Capical]. Mass spectrum
(FAB): m/z 875 (Mϩ, 10%, C46H40ClN6P2Ru), 840 (6, M Ϫ Cl),
731 (5), 641 (3, M Ϫ PPh3 ϩ N2), 625 (14, M Ϫ TPM Ϫ Cl),
613 (100, M Ϫ PPh3), 607 (16).
[RuCl(PPh3)2(TPM)]ϩBF4Ϫ 3b. A solution of NaBF4
(10 mg, 0.88 mmol) in ethanol (5 mL) was added to a solution
of [RuCl(PPh3)2(TPM)]ϩClϪ 3a (100 mg, 0.11 mmol) in ethanol
(5 mL). The mixture was heated and then allowed to cool.
The product was isolated and recrystallised from methanol.
Chlorobis(triphenylphosphine)[tris(1-pyrazolyl)methane]-
ruthenium() tetrafluoroborate 3b was obtained as small yellow
crystals (95 mg, 90%), mp decomposes at 176 ЊC. Found: C,
55.4; H, 4.2; N, 8.7. C46H40N6P2BF4Ru ϩ 3MeOH requires C,
55.6; H, 4.95; N, 7.9%. IR νmax/cmϪ1(KBr disc): 3415b, 3137w,
3059w, 2966w, 1622w, 1481m, 1434s, 1289m, 1092s, 1055s,
858w, 796m, 748s, 698s, 604w, 522s. Mass spectrum (FAB): m/z
875 (Mϩ, 15%, C46H40ClN6P2Ru), 841 (6, M Ϫ Cl), 731 (9), 641
(5, M Ϫ PPh3 ϩ N2), 625 (22, M Ϫ TPM Ϫ Cl), 613 (100,
M Ϫ PPh3), 607 (17). Complete NMR data have been deposited
as electronic supplementary material.
PRu ϩ 1MeOH requires C, 52.0; H, 4.6; N, 14.7%) IR νmax
/
cmϪ1 (KBr disc): 3406b, 3105w, 3054w, 3001w, 1623w, 1516w,
1480m, 1434s, 1281s, 1184m, 1092s, 997w, 749s, 696s, 603w,
529s, 503m. δH (400 MHz; solvent MeOD) 8.46 [1H, d, Hr], 8.43
[1H, dd, Hc], 8.25 [1H, dd, Hf], 8.23 [1H, d, He], 8.21 [1H, dd,
Hp], 8.17 [1H, dd, Hm], 7.55–7.21 [15H, m, aromatics], 7.54 [1H,
d, Ha], 6.99 [1H, d, Hd], 6.74 [1H, dd, Hq], 6.69 [1H, d, HЊ], 6.52
[1H, dd, Hb], 6.47 [1H, dd, Hl], 6.41 [1H, dt, Hg], 6.04 [1H, d,
Hk], 5.86 [1H, d, Hh], 5.72 [1H, d, Hn]. δP{1H} (162 MHz; solvent
MeOD) 50.8. δ13C{1H}; (100 MHz; solvent MeOD) 151.6 [Ca],
148.8 [Cr], 147.1 [Ck], 144.2 [Ch], 137.0 [Cc], 136.4 [Cm], 136.0
[Cp], 134.6 [Cf], 134.6–128.8 [PPh3], 110.0 [Cl], 109.4 [Cq], 109.1
[Cb], 108.9 [Cg], 64.3 [Cd,e], 63.4 [Co,n]. Complete NMR data
have been deposited as electronic supplementary material.
Mass spectrum (FAB): m/z 695 (Mϩ, 100%, C32H31ClN8PRu),
660 (3.81, M Ϫ Cl).
Carbonylhydrido(triphenylphosphine)[tris(1-pyrazolyl)-
Bis[bis(1-pyrazolyl)methane]tri-ꢀ-chlorobis(triphenyl-
methane]ruthenium(II) chloride 4a and tetrafluoroborate 4b
[Ru(CO)(H)(PPh3)(TPM)]؉X (X ؍ Cl 4a or BF4 4b).[Ru(CO)-
(H)(PPh3)(TPM)]ϩClϪ 4a. A mixture of Ru(CO)ClH(PPh3)3
(573 mg, 601 mmol) and TPM (142 mg, 661 mmol) was
refluxed vigorously in toluene (25 mL) for 3 hours. The crude
product precipitated and was isolated by filtration and
washed with hot toluene. [Ru(CO)(H)(PPh3)(TPM)]ϩClϪ 4a
was obtained as a cream coloured powder (176 mg, 43%), mp
decomposes at 163 ЊC. Found: C, 53.5; H, 4.1; N, 12.45.
phosphine)diruthenium(II)chloride
[(BPM)(Ph3P)Ru(ꢀ-Cl)3-
Ru(PPh3)(BPM)]؉Cl؊ 6. A solution of BPM (160 mg, 1.0
mmol) and RuCl2(PPh3)3 (530 mg, 0.55 mmol) in DCM (40 mL)
was stirred for 2 hours, then filtered and the orange residue
discarded. The clear amber filtrate was reduced in volume and
unchanged RuCl2(PPh3)3 precipitated. The mixture was filtered
and the solvent removed to give a yellow powder, which was
recrystallised from methanol at room temperature to give
the product bis[bis(1-pyrazolyl)-methane]tri-µ-chlorobis(tri-
phenylphosphine)diruthenium() chloride 6 as red crystals
from a yellow solution. δH (400 MHz; solvent d6-DMSO) 8.40
C29H26ClN6OPRu requires C, 54.2; H, 4.1; N, 13.1%. IR νmax
/
cmϪ1(KBr powder): 1934vs (CO). δH (400 MHz; solvent
5
MeOD) 9.82 [1H, s, Hapical], 8.58 [1H, d, HC ], 8.49 [1H, d, HA5],
3
3
3
[2H, d, J = 2.5], 8.02 [2H, d, J = 2.5], 7.84 [2H, d, J = 2.5],
7.49–7.29 [30H, m, aromatics], 7.19 [2H, d, 3J = 2.5], 6.68 [2H, t,
3J = 14.2], 6.39 [2H, t, 3J = 2.52], 4.85 [4H, d, 3J = 14.2 Hz].
5
8.45 [1H, d, HB ], 8.24 [1H, d, HA3], 7.69 [3H, m, HPhpara], 7.59
3
[6H, m, HPhortho], 7.55 [6H, m, HPhmeta], 7.07 [1H, d, HC ], 6.78
3
4
[1H, d, HB ], 6.71 [1H, dd, 3.1 Hz, HA4], 6.57 [1H, dd, HC ], 6.30
4
[1H, dd, HB ], Ϫ12.12 [1H, d, Hhydride]. δP{1H}(162 MHz; solvent
Crystal data, X-Ray data collection, and structure determination
MeOD) 63.5. δC{1H}(100 MHz; solvent MeOD) 206.3 [d, 3JC-Ru–P
18.1, Ru–CO], 149.1 [CB ], 149.0 [CA3], 147.4 [CC ], 134.8 [d,
(a) [RuCl(PPh3)2(TPM)]ClؒPPh3ؒ2CH3CH2OH 3a. The
crystal data are summarised in Table 2. Cell constants were
3
3
5
5
3JCP 10.7, CPhmeta], 135.2 [CC ], 135.0 [CB ], 134.5 [CA5], 132.2 [d,
J. Chem. Soc., Dalton Trans., 2001, 1959–1965
1963

View Article Online
Table 2 Crystallographic data for [RuCl(PPh3)2(TPM)]ClؒPPh3ؒ2CH3CH2OH 3a and [(BPM)(Ph3P)Ru(µ-Cl)3Ru(PPh3)(BPM)]ϩClϪ
6
3a
6
Empirical formula
Formula weight
C56H54Cl2N6O2.2P2.33Ru
1090.43
C53H46Cl4N8O4P2Ru2
1264.90
Crystal system
Space group
Rhombohedral
R3
Monoclinic
P21/n
¯
Z
6
4
µ/cmϪ1
(Mo-Kα) 4.30
20.022(4)
(Cu-Kα) 38.9
16.089(3)
10.260(2)
33.837(7)
a/Å
b/Å
c/Å
α/Њ
90.73(2)Њ
β/Њ
96.80(1)
5546(2)
V/Å3
8024.5(8)
T/K
293
294
No. of reflections measured
No. observations
(I > 2.50σ(I))
No. variables
Residuals: R, Rw
Total 10977, Unique 6318
5084
Total 6449, Unique 6105
4865
722
0.048, 0.051
644
0.045, 0.049
2 See for examples: T. N. Sorrell and A. S. Borovik, J. Am. Chem. Soc.,
1987, 109, 4255; R. S. Brown, D. Salmon, N. J. Curtis and
S. Kusuma, J. Am. Chem. Soc., 1982, 104, 3188; F. Chu, J. Smith,
V. M. Lynch and S. J. Lippard, Inorg, Chem., 1995, 34, 5689;
C. C. Tang, D. Davalian, P. Huang and R. Breslow, J. Am. Chem.
Soc., 1978, 100, 3918; R. Breslow, J. T. Hunt, R. Smiley and
T. Tarnowski, J. Am. Chem. Soc., 1983, 105, 5337.
3 P. Frediani, M. Bianchi, A. Salvini, R. Guanducci, L. C. Carluccio
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4 F. A. Jalón, A. Otero, A. Rodríguez and M. Pérez-Manrique,
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2219.
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Int., 1984, 16, 299.
9 A. Llobet, M. E. Curry, H. T. Evans and T. J. Meyer, Inorg. Chem.,
1989, 28, 3131; A. Llobet, P. Doppelt and T. J. Meyer, Inorg. Chem.,
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10 (a) L. A. Oro, M. Esteban, R. M. Claramunt, J. Elguero, C. Foces-
foces and F. H. Cano, J. Organomet. Chem., 1984, 276, 79; (b) M. A.
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J. Organomet. Chem., 1989, 366, 245.
determined by least-squares fit to the setting parameters of
25 independent reflections, measured and refined on an
Enraf-Nonius CAD4-F diffractometer with a graphite mono-
chromator. Data were reduced and Lorentz, polarisation and
absorption corrections applied using the Enraf-Nonius struc-
ture determination package (SDP).37 The structure was solved
by direct methods using SHELXS 8638 and refined by blocked-
matrix least-squares analysis with SHELX 76.39 Hydrogen
atoms were included at calculated sites (C–H, 0.97 Å) with indi-
vidual isotropic thermal parameters. All other atoms except
contributors to disordered groups (PPh3, CH3CH2OH) were
refined anisotropically. Scattering factors and anomalous dis-
persion corrections were taken from the values supplied in
SHELX 76. Figures were drawn using ORTEP.23
(b) [Ru(ꢀ-Cl)3Ru(PPh3)(BPM)]؉Cl؊ 6. The crystal was
mounted on a glass fibre with cyanoacrylate resin. Lattice
parameters at 21 ЊC were determined by least-squares fit to the
setting parameters of 25 independent reflections, measured and
refined on an AFC-7 four-circle diffractometer employing
graphite monochromated Cu-Kα radiation. Data reduction and
application of Lorentz, polarisation, absorption and decom-
position corrections were carried out using the TEXSAN
system.40
The structure was solved by direct methods using SHELXS
86.38 Hydrogen atoms were included at calculated sites with
fixed isotropic thermal parameters. All other atoms were refined
anisotropically. Full-matrix least-squares methods were used to
refine an overall scale factor, positional and thermal param-
eters. Neutral atom scattering factors were taken from Cromer
and Waber.41 Anomalous dispersion effects were included in
Fc;42 the values for ∆fЈ and ∆fЉ were those of Creagh and
McAuley.43 The values for the mass attenuation coefficients
are those of Creagh and Hubbell.44 All calculations were
performed using TEXSAN40 and plots were drawn using
ORTEP.23
11 A. J. Canty and N. J. Minchin, J. Organomet. Chem., 1982, 226, C14;
H. C. Clark and M. A. Mesubi, J. Organomet. Chem., 1981, 215,
131.
12 P. K. Byers, A. J. Canty, B. W. Skelton and A. H. White,
Organometallics, 1990, 9, 826.
13 F. Mani, Inorg. Nucl. Chem. Lett., 1979, 15, 297.
14 C. Pettinari, C. Santini and D. Leonesi, Polyhedron, 1994, 13,
1553.
15 F. Mani, Inorg. Chim. Acta, 1980, 38, 97.
16 K. B. Shui, K. S. Liou, Y. Wang, M. C. Cheng and G. H. Lee,
J. Organomet. Chem., 1993, 453, 201.
17 A. Looney and G. Parkin, Polyhedron, 1990, 9, 265.
18 G. Bellachioma, G. Cardaci, A. Maccioni, G. Reichenbach and
S. Terenzi, Organometallics, 1996, 15, 4349; A. Maccioni, G.
Bellachioma, G. Cardaci, V. Gramlich, H. Rueegger, S. Terenzi and
L. M. Venanzi, Organometallics, 1997, 16, 2139.
19 A. Llobet, D. J. Hodgson and T. J. Meyer, Inorg. Chem., 1990, 29,
3760.
CCDC reference numbers 158383 and 158384.
See http://www.rsc.org/suppdata/dt/b1/b103939n/ for crystal-
lographic data in CIF or other electronic format.
20 M. Fajardo, A. de la Hoz, E. Diéz-Barra, F. A. Jalón, A. Otero,
A. Rodríguez, J. Tejeda, D. Belletti, M. Lanfranchi and M. A.
Pellinghelli, J. Chem. Soc., Dalton Trans., 1993, 1935.
21 T. A. Stephenson and G. Wilkinson, J. Inorg. Nucl. Chem., 1966, 28,
945.
22 N. Ahmad, J. J. Levison, S. D. Robinson and M. F. Uttley, Inorg.
Synth., 1974, 15, 45.
Acknowledgements
We gratefully acknowledge financial support from the
Australian Research Council and The University of Sydney for
an H. B. and F. M. Gritton Scholarship (L. S.).
23 C. K. Johnson, ORTEP, A Thermal Ellipsoid Plotting Program,
Oak Ridge National Laboratory, Oak Ridge, TN, 1965.
24 N. W. Alcock, I. D. Burns, K. S. Claire and A. F. Hill, Inorg. Chem.,
1992, 31, 2906.
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J. Chem. Soc., Dalton Trans., 2001, 1959–1965

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