A facile access to a novel bidentate enantiomerically pure P,N-donor ligand

Article abstract of DOI:10.1039/b822144h

The synthesis of a new chiral P,N-donor ligand containing a phosphite and a pyrazole site and its coordination chemistry with transition metals are described. The Royal Society of Chemistry 2009.

Full text of DOI:10.1039/b822144h

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PAPER
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A facile access to a novel bidentate enantiomerically pure P,N-donor ligand†
Christoph K. Seubert, Yu Sun and Werner R. Thiel*
Received 10th December 2008, Accepted 16th April 2009
First published as an Advance Article on the web 8th May 2009
DOI: 10.1039/b822144h
The synthesis of a new chiral P,N-donor ligand containing a phosphite and a pyrazole site and its
coordination chemistry with transition metals are described.
In this paper we present a rapid access to a novel P,N-donor con-
Introduction
taining a phosphite derived from 1,1¢-binaphthol and a pyrazole
During the last two decades enantioselective transition metal
site. Additionally, transition metal complexes were synthesized
catalysis became an important tool in organic synthesis. There-
to demonstrate the special geometric features of this ligand. It
fore, there is a permanent demand for novel chiral ligands.
is often assumed, that a bidentate ligand will undergo chelating
Among these ligands, systems containing the atropisomeric
coordination and that the resulting coordination geometry is rigid.
1,1¢-binaphthalene subunit are extensively used for catalytic
applications.1 The most famous example of a binaphthalene
ligand is 2,2¢-bisdiphenylphosphino-1,1¢-binaphthalene (BINAP)
introduced by Noyori et al.2 Also there are ligands bearing
two different P-donor subunits like BINAPHOS, a binaphthyl
ligand with both, a phosphine and a phosphite donor site.3 The
replacement of one of the phosphorus donors by a nitrogen
donor provides further electronic differentiation. During the
last twenty years a variety of different P,N-ligands have been
published,4 also including binaphthalene ligands, such as MAP or
axial-phox ligands.5
The ligands discussed above, except BINAPHOS, contain a
phosphine subunit. But during the last ten years, phosphites and
phosphonites have attracted more and more attention as ligands
for transition metal catalysis.3d,6 Their outstanding features such as
the p-acidity and the synthetic accessibility have led to applications
in a series of asymmetric catalytic reactions such as palladium
catalyzed allylic substitution,6c,7 rhodium catalyzed hydrogenation
of olefins3d,7b,8 or ruthenium catalyzed hydrogenation of ketones.9
Due to the facile accessibility of enantiomerically pure R- and S-
BINOL and the beneficial stereochemical impact of this fragment,
1,1¢-binaphthyl is often used as the chiral backbone.3d,6b,7a,b,8 It can
be combined with achiral or chiral alcohols as well as with nitrogen
bearing subunits like imines, quinolines or oxazolines.7b,10
To our knowledge, bidentate chiral P,N-ligands containing a
pyrazole subunit have only been published once. Togni et al.
reported a pyrazole functionalized chiral phosphinoferrocene
in 1995.11 Besides its simple synthetic accessibility,12 the main
advantage of the pyrazole donor unit is its simple modification by
introduction of different functional groups in all ring positions.13
Following this strategy, the steric and electronic properties of
the ligands can be tuned without changing the character of the
donor unit.
We will show an example of a quite fluxional ligand backbone and
another one with a rigid backbone, both derived from the same
P,N-donor ligand.
Results and discussion
As outlined in Schemes 1 and 2, the synthesis of the target
ligand follows a convergent strategy with an overall yield of
about 70%. Although the precursor compound 2 has already been
described in the literature,14 we decided to develop an alternative
access, since it was only obtained along with its regioisomer 5-
(2-hydroxyphenyl)(1-methyl)pyrazole. The separation of the two
isomers requires column chromatography. A few years ago, we
reported the synthesis of compound 1,15 which is available in
high yield in two steps by treating 2-hydroxyacetophenone with
N,N-dimethylformamide dimethylacetal under microwave heating
followed by ring closure with hydrazine.
Scheme 1 (i) DMFDMA, microwave irradiation, 650 W, 5 min.;
(ii) N2H4·H2O, EtOH, reflux, 4 h; (iii) NaH, MeI, THF, RT, 16 h.
Fachbereich Chemie, TU Kaiserslautern, Erwin-Schro¨dinger-Str. Geb. 54,
67663, Kaiserslautern, Germany. E-mail: thiel@chemie.uni-kl.de; Fax: +49
631 2054647; Tel: +49 631 2052752
† Electronic supplementary information (ESI) available: X-ray data, NMR
and IR spectra. CCDC reference numbers 713118–713120. For ESI
and crystallographic data in CIF or other electronic format see DOI:
10.1039/b822144h
Scheme 2 (i) PCl3, NMP, RT, 16 h (ii) 2, NEt3, THF, 0 ◦C, 2 h, RT, 12 h.
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Based on experiences in the N-methylation of pyrazolyl-
pyridines, it seemed likely that deprotonation of both the OH and
the NH group of 1 followed by addition of CH3I will selectively
provide the desired regioisomer 2. Whenever a nitrogen atom of
the pyrazolide anion is involved in a chelating coordination to a
metal cation, this nitrogen atom will not be alkylated. In the case
of 1, the phenolate and the pyrazolide moiety undergo chelation to
Na+ (from NaH). Therefore, besides 2 only traces of the undesired
regioisomer were formed. The yield of this reaction is at about
90%. A further advantage of this methodology is that it allows the
introduction of other alkyl and aryl16 groups which permits the
fine-tuning of the steric demand of the pyrazole site.
the interconversion of the two isomers might be high enough to
make these isomers observable by NMR at room temperature.
Scheme 4 presents a sketch of the two isomers in equilibrium
with differently twisted seven membered rings. Since this twist
introduces a helix along the phenol–pyrazole bond and since the
chirality of the 1,1¢-binaphthol fragment does not change, these
isomers are diastereomers.
Scheme 2 shows the preparation of the phosphite unit. R–
BINOL was prepared according to published procedures.17 The
subsequent synthesis of the chlorophosphite 3 was performed in a
slightly modified published procedure.18 Treatment of 3 with 2 in
THF in the presence of triethylamine as the base gave the desired
P,N-ligand 4 in good yield.
Scheme 4 Schematic representation of the diastereomers of com-
pound 5.
1
To prove this hypothesis, a series of 31P{ H}-NMR spectra were
Ligand 4 was characterised by NMR and infrared spectroscopy.
1
recorded at different temperatures with o-dichlorobenzene (bp:
The H NMR spectrum shows a singlet at 3.99 ppm which can
446 K) as the solvent. The results are shown in Fig. 1.
be assigned to the NCH3 group and a doublet at 6.63 ppm
with a small coupling constant (3JHH = 1.8 Hz) typical for the
proton in the 4-position of the pyrazole fragment. The remaining
aromatic protons give two complex multiplets at 7.16–7.62 and
7.85–8.08 ppm corresponding to 12 and 5 protons. Due to the
large number of aromatic protons, a more detailed assignment
1
was impossible. The 13C{ H} NMR spectrum shows the expected
number of 30 13C resonances, which means that the two naphthyl
rings are not equivalent. This is due to the sp3 hybridized
phosphorus atom, bearing one further oxygen atom and the lone
1
pair additionally to the two BINOL oxygen atoms. The 31P{ H}
NMR spectrum of 4 shows a singlet at 148.9 ppm in the typical
region for phosphites.7b,19 Since compound 4 is moisture sensitive,
it has to be stored under an atmosphere of nitrogen and all
reactions have to be carried out in dried solvents.
To investigate its coordination chemistry, 4 was reacted with
(PhCN)2PdCl2 in dichloromethane solution at room temperature.
The desired palladium complex 5 could be obtained in 89% yield
as a yellow solid (Scheme 3).
Fig. 1 Dynamic 31P NMR spectra of 5.
At room temperature there are two well separated resonances
corresponding to two diastereomeric complexes as mentioned
above. Raising the temperature makes the signals become broader
until there is only one resonance observable at the final tempera-
ture (420 K). The point of coalescence is 370 K.
Single crystals of the palladium complex 5, which were suitable
for X-ray diffraction, could be obtained by recrystallization from
acetonitrile. One equivalent of the solvent per formula unit of 5 was
found in the crystal. The molecular structure and characteristic
structural parameters of 5 are shown in Fig. 2.
The X-ray structure analysis confirms the spectroscopic data
discussed above. The metal site is coordinated in a distorted square
planar manner, the bond parameters are typical for complexes
of the type (P-N)PdCl2 (N = aromatic N-donor).5b,6c,d,10,20 The
Pd–Cl distances follow the influence of the donor sites in the
trans position. Fig. 2 (bottom) shows the helical twist of the
binaphthyl unit with a dihedral angle of 52.2(5)◦. A similar
situation is found for the seven membered ring, which is generated
by coordination of 4 to the PdCl2 fragment. The dihedral angle
between the phenol and the pyrazole ring is 42.9(5)◦. While the
stereochemistry of the binaphthyl unit is conserved due to steric
Scheme 3 (i) (PhCN)2PdCl2, CH2Cl2, RT, 4 h.
1
The 31P{ H} NMR spectrum of 5 measured in CD3CN shows
two resonances at 97.6 and 99.2 ppm in a 6:4 ratio. Changing
1
the solvent to CDCl3 changes the ratio to 2:8. In the H NMR
spectrum two sets of signals with the same solvent depending
ratios were observed. Elemental analysis indicates the formation
of a palladium(II) complex of the overall composition (4)PdCl2.
Therefore the most likely explanation for the doubled sets of
1
1
resonances in the 31P{ H} and H NMR spectra is the presence
of two isomeric compounds in solution. The only source for
this isomerism can be the twist of the seven membered ring
generated by the coordination. A seven membered ring containing
flexible single bonds will never be planar, but the barrier for
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fact that the 1H NMR resonances of the pyrazole unit are observed
at almost the same chemical shifts as for the free ligand 4, indicate
a monodentate P-coordination of the P,N-ligand in compound
6. This observation is consistent with reports in the literature
6
on the coordination chemistry of (h -para-cymene)RuCl2.21 The
exchange of one chlorido ligand against a pyrazole donor is very
slow for the 18e- compound.
Coordination of 4 to ruthenium causes a separation of nearly
all signals in the H and 13C{ H} NMR spectra. Therefore an
assignment of almost every signal could be realized by combining
one- and two-dimensional NMR methods (H,H-Cosy-, HMQC-,
HMBC- and J-resolved NMR spectroscopy). The presence of
the chiral phosphite ligand results in two doublets for the
diastereotopic methyl groups of the isopropyl unit (1.11 and
1.16 ppm) in the 1H NMR spectrum. The methine proton of
the isopropyl unit gives a septet at 2.80 ppm. Two singlets at
1.97 and 4.08 ppm could be assigned to the methyl groups of
the cymene and the pyrazole ligand. The aromatic protons of the
cymene ring, which became chemically inequivalent due to the
coordination of the chiral phosphite ligand, appear at high field
as four doublets (5.00, 5.24, 5.30, 5.59 ppm) with almost identical
coupling constants. The H,H-Cosy spectrum shows correlation
between the signals at 5.00 and 5.59 and the signals at 5.24 and
5.30 ppm. Each of these couples therefore belongs to one side of
the cymene ring. The presence of the pyrazole is characterized
by two doublets at 6.80 and 7.58 ppm with a typical small
coupling constant of about 2 Hz. There are two doublets (7.69,
7.75 ppm) and two triplets (7.13, 7.20 ppm) for the phenol ring.
The clearly separated resonances of the twelve different protons of
the binaphthyl system are observed at 7–8 ppm. As expected, the
1
1
Fig.
2 Solid state structure of 5 (top), view along the C5–C3
axis (bottom); the molecule of acetonitrile is omitted for clarity.
Characteristic bond lengths [A], angles [deg] and dihedral angles
˚
[deg]: Pd–Cl1 2.3347(8), Pd–Cl2 2.2693(10), Pd–P 2.1776(8), Pd–N2
2.036(3), Cl1–Pd–Cl2 92.93(3), Cl1–Pd–P 172.58(3), Cl1–Pd–N2 87.95(8),
Cl2–Pd–P 94.16(3), Cl2–Pd–N2 178.72(8), P–Pd–N2 84.99(8), Cl2–Pd–
P–O1 135.95(11), N2–Pd–P–O1 –45.01(13), Cl1–Pd–N2–C3 -100.5(2),
N2–C3–C5–C6 -42.9(5), P–O1–C6–C5 79.2(4), C11–C12–C22–C21
-52.2(5), C2–C3–C5–C6 42.9(5).
1
13C{ H} NMR spectrum shows the resonances for forty different
carbon positions. A MALDI-TOF mass spectrum gave a signal
at m/z = 759 which could be assigned to the cation [6-Cl]+.
Single crystals suitable for X-ray diffraction could be obtained by
crystallization from toluene/THF. The molecular structure and
characteristic structural parameters of 6 are shown in Fig. 3.
Compound 6 crystallizes with one equivalent of toluene and
half an equivalent of THF per formula unit. Both solvents are
crystallographically disordered.
restrictions, the helical chirality of the second seven membered
ring can change as discussed above.
Reacting ligand 4 with the dimeric ruthenium complex [(h -
6
para-cymene)RuCl2]2 at room temperture in CH2Cl2 gave the red
As predicted by the spectroscopic data of 6, the ligand binds
to the ruthenium centre solely by the phosphorus atom. The
coloured ruthenium(II) complex 6 in high yield (Scheme 5). A
1
single resonance in the 31P{ H} NMR spectrum at 134 ppm and the
6
bond parameters are typical for complexes of the type (P)(h -
para-cymene)RuCl2.21a,22 The dihedral angles between the binaph-
thyl units (55.2◦) and the phenole and the pyrazole ring (49.0◦) are
comparable to those found in the palladium complex 5.
6
To enforce a bidentate coordination of the P,N-ligand, [(h -
para-cymene)RuCl2]2 was first reacted with AgClO4 in acetonitrile
to exchange one chlorido ligand against a perchlorate anion.
Subsequent addition of 4 dissolved in CH2Cl2 provides the desired
chelatecomplex 7. The1HNMRspectrum shows four independent
sets of signals in a 10/3.5/2/0.5 ratio indicating the formation
of four diastereomers. The 31P NMR spectrum of 7 recorded at
room temperature shows only three resonances at 144.4, 142.0
and 137.7 ppm due to the low percentage of the minor isomer.
Additionally to the helical axis of the binaphthyl fragment,
there are two further elements of chirality in this compound:
the twisted phenyl-pyrazolyl moiety and the ruthenium centre,
which is coordinated to four different ligand sites. Due to the
6
6
Scheme 5 (i) [(h -para-cymene)RuCl2]2, CH2Cl2, RT, 24 h; (ii) [(h -para-
1
cymene)RuCl2]2 + AgClO4, MeCN, RT, 2 h.
presence of four diastereomeric species, the 1H and 13C{ H} NMR
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As expected, ligand 4 now coordinates the ruthenium centre in a
bidentate manner, the Ru–P distance is slightly longer, the average
Ru–Ccymene distance is slightly longer and the Ru–Cl distance
is identical as compared to compound 6. The dihedral angles
between the naphthyl units (50.7◦) and the phenol and the pyrazole
ring (127.8(5)◦ & 52.2(5)◦) are also quite similar to the values
found for 6. This means, that the twist between the phenol and
the pyrazole ring is mainly determined by the steric hinderance
between these two ring systems and not by restrictions resulting
from the coordination.
The NMR spectra of the crystals redissolved at room tem-
perature showed only one set of signals. It is the major isomer
1
found in freshly synthesized 7 (31P NMR: 144.6 ppm). In the H
NMR spectrum resonances in the aromatic region (7.1–8.3 ppm)
corresponding to twelve protons of the binaphthyl subunit and
four protons of the phenol are observed. A clear assignment of
these resonances to the different ring positions was not possible
even by use of H,H-Cosy and HMQC techniques. Two doublets
3
(7.88, 6.48 ppm; JHH = 2.4 Hz) can be assigned to the two
protons of the pyrazole ring, four doublets (6.00, 5.90, 5.80 and
5.41 ppm) correspond to the hydrogen atoms of the cymene ring.
The resonance of the N-CH3 group is found at 4.51 ppm. It is
shifted about 0.5 ppm towards lower field compared to 6. The
signals of the aliphatic protons of the substituents at the cymene
ring are detected at 2.49 ppm (septet, CH(CH3)2), 0.94, 0.71 ppm
(doublets, CH(CH3)2) and 1.66 ppm (singlet, CH3). In the 13C
NMR spectrum there are five signals in the aliphatic region, four
signals between 89 and 97 ppm (four tertiary carbon atoms of
cymene) and 31 signals in the aromatic region as expected.
Fig. 3 Solid state structure of 6; the disordered solvent molecules
are omitted for clarity. Characteristic bond lengths [A], angles [deg]
˚
and dihedral angles [deg]: Ru–Cl1 2.3876(14), Ru–Cl2 2.4211(14), Ru–P
2.2351(13), Ru–C31 2.246(6), Ru–C32 2.267(6), Ru–C33 2.235(6), Ru–C34
2.192(6), Ru–C35 2.156(6), Ru–C36 2.208(6), Cl1–Ru–Cl2 89.03(5),
Cl1–Ru–P 85.50(5), Cl2–Ru–P 88.10(5), C11–C12–C22–C21 -55.2(6),
C2–C3–C5–C6 -49.0(8).
spectra are too complicated to be assigned in detail. A MALDI-
TOF mass spectrum gave a signal at m/z = 759 which could be
assigned to the cation [7-ClO4]+. The infrared spectrum shows a
strong absorption at 1090 cm-1 corresponding to the perchlorate
anion. Crystalization of 7 from CHCl3/n-pentane afforded red
crystals suitable for X-ray diffraction. The molecular structure
and characteristic structural parameters of 7 are shown in Fig. 4.
Compound 7 crystallizes with one molecule of chloroform per
formula unit.
During all these measurements, we did not observe the reforma-
tion of the other diastereomers. The NMR spectra were recorded
in the non-coordinating solvent CDCl3 and it took about 24 h to
get the complete set of spectra. Brunner et al. recently reported
6
chiral neutral complexes of the type (h -para-cymene)RuCl(L)
(L = bidentate ligand) which epimerized with half-lives of about
◦
1 h at 0 C.23 The mechanism of the epimerization in these
cases is still not finally clarified. For our case we expected to
observe the interconversion of the chelate ring as in the case
for the palladium complex 5 since there is no real difference in
the structural parameters of the seven-membered ring between
5 and 7. Maybe there is steric hinderance between the methyl
group at the pyrazole ligand and the chlorido ligand at ruthenium,
preventing this equilibration reaction, which should give a second
diastereomer.
Conclusion
The ligand system presented here is the first example out of a
whole family of pyrazole containing phosphines, phosphinites and
phosphites, which are accessible by similar reactions and which
are under investigation in our group at the moment. The chiral
P,N-donor ligand gives palladium and ruthenium complexes in
high yields when treated with appropriate precursor complexes.
Due to the seven membered ring formed by the chelating
coordination, these complexes may show dynamic behavior in
solution. Moreover, this synthetic route can be used to prepare
a large number of ligands carrying different steric and electronic
properties. This can be achieved without changing the geometry
of the donor sites by substitution of the pyrazole subunit.
Fig. 4 Solid state structure of the cation of compound 7; the solvent
molecule and the perchlorate anion are omitted for clarity. The carbon
6
atoms of the h -cymene unit are numbered as in Fig. 3. Character-
˚
istic bond lengths [A], angles [deg] and dihedral angles [deg]: Ru–Cl1
2.3854(10), Ru–N2 2.125(3), Ru–P 2.2577(10), Ru–C31 2.259(3), Ru–C32
2.201(4), Ru–C33 2.209(4), Ru–C34 2.276(4), Ru–C35 2.255(4), Ru–C36
2.216(4), Cl1–Ru–N2 92.86(10), Cl1–Ru–P 83.26(3), N2–Ru–P 83.93(10),
C11–C12–C22–C21 -50.7(5), C2–C3–C5–C6 127.8(5) & 52.2(5).
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added to a solution of 95.8 mg (0.25 mmol) (PhCN)2PdCl2 in 5 mL
of CH2Cl2. The resulting red–brown solution was stirred for 2 h
at room temperature, after which the colour changed to yellow.
The solvent was reduced to 5 mL, 20 mL of diethyl ether were
added and the resulting precipitate was collected by filtration.
After washing it twice with 10 mL of diethyl ether it was dried
in vacuum. Yield: 148 mg (89%), yellow solid. Anal. calcd. for
C30H21Cl2N2O3PPd·(CH3CN) (706.85): C, 54.38; H, 3.42; N, 5.94;
found: C, 54.48; H, 3.40; N, 5.81. IR (KBr, cm-1): 2963, 1509, 1261,
1221, 1183, 1091, 1068, 102◦6, 960, 927, 804.
Experimental
General
All reactions were carried out under an atmosphere of dinitrogen,
the solvents were dried before use. Chemicals were purchased from
Acros Organics, Sigma Aldrich and Strem chemicals. Compounds
1 and 3 were synthesised according to published procedures.8,15
The NMR spectra (Bruker DPX 400 and Bruker Avance 600),
the infrared spectra (JASCO FT/IR-6100), mass spectra (Bruker
ultraflex TOF/TOF), the X-ray structure analyses and elemental
analyses (Perkin-Elmer Elementar Analyser 2400 CHN) were
carried out at the Technischen Universita¨t Kaiserslautern.
1H NMR (600 MHz, 25 C, CD3CN): major isomer d 8.33 (d,
1H, 3JHH = 9.0 Hz, HAr), 8.29 (d, 1H, 3JHH = 9.0 Hz, HAr), 8.09–
0.16 (m*, 2H, HAr), 7.98–8.01 (m*, 2H, HAr), 7.93 (d, 1H, 3JHH
9.0 Hz, HAr), 7.90 (d, 1H, 3JHH = 9.0 Hz, HAr), 7.77 (t, 1H, 3JHH
=
=
Syntheses
7.8 Hz, HAr), 7.71–774 (m*, 1H, HAr), 7.64–7.70 (m*, 1H, HAr),
7.55–7.61 (m*, 1H, HAr), 7.51–7.55 (m*, 1H, HAr), 7.30–7.38 (m*,
3-(2-Hydroxyphenyl)(1-methyl)pyrazole (2).
A solution of
3
2H, HAr), 7.21–7.29 (m*, 2H, HAr), 6.66 (d, 1H, JHH = 2.6 Hz,
2.45 g (15.3 mmol) of 1 in 90 mL of dry THF was slowly treated
with 735 mg (30.6 mmol) of NaH at 0 ◦C. The mixture was warmed
up to room temperature and stirred for a further 2 h until hydrogen
evolution ceased. 950 mL (15.3 mmol) of methyliodide dissolved in
60 mL of dry THF were added dropwise and the resulting mixture
was stirred for 12 h at room temperature. The solvent was removed
in vacuum and 50 mL of a 1 M solution of NaHCO3 were added to
the residue. The aqueous solution was extracted three times with
50 mL of diethyl ether, the organic phases were combined, dried
over Na2SO4, and the solvent was evaporated. Yield: 2.39 g (90%),
pale yellow solid. 1H NMR (400 MHz, 25 ◦C, CDCl3): d 10.80 (br,
H4Pz), 4.57 (s, 3H, CH3); minor isomer d 8.09–0.16 (m*, 1H, HAr),
3
3
8.06 (d, 1H, JHH = 8.2 Hz, HAr), 8.03 (d, 1H, JHH = 2.6 Hz,
H5Pz), 7.98–8.01 (m*, 1H, HAr), 7.71–774 (m*, 2H, HAr), 7.64–
7.70 (m*, 2H, HAr), 7.55–7.61 (m*, 3H, HAr), 7.51–7.55 (m*, 1H,
HAr), 7.30–7.38 (m*, 2H, HAr), 7.21–7.29 (m*, 2H, HAr), 6.92 (d,
1H, 3JHH = 9.0 Hz, HAr), 6.78 (d, 1H, 3JHH = 2.6 Hz, H4Pz), 4.26 (s,
3H, CH3), signals assigned with an * are superimpos◦ed with those
1
of the other isomer. 31P{ H} NMR (242.94 MHz, 25 C, CD3CN):
d 99.2 (s), 97.6 (s).
Dichlorido[(g6 -para-cymene)(4-(2-(1-methylpyrazol-3-yl))phe-
nyloxy)-3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4-a¢]dinaphtha-
lene]ruthenium(II) (6). A solution of 125 mg (0.25 mmol) of
3 in 10 mL of CH2Cl2 was added to a solution of 76.5 mg
3
4
1H, OH), 7.56 (dd, 1H, JHH = 7.8 Hz, JHH = 1.6 Hz), 7.39 (d,
1H, 3JHH = 2.4 Hz, H5Pz), 7.18–7.23 (m, 1H), 7.02 (dd, 1H, 3JHH
=
=
4
3
8.2 Hz, JHH = 1.2 Hz), 6.88–6.93 (m, 1H), 6.61 (d, 1H, JHH
2.4 Hz, H4Pz), 3.94 (s, 3H, CH3). 13C{ H} NMR (150.37 MHz,
25 ◦C, CDCl3) 155.9 (s, C–OH), 151.5 (s), 131.1 (s), 129.1 (s),
126.3 (s), 119.3 (s), 117.1 (s), 116.9 (s), 102.3 (s, C4Pz), 39.1 (s,
CH3).
1
6
(0.13 mmol) of [(h -para-cymene)RuCl2]2 in 5 mL of CH2Cl2.
The resulting red–brown solution was stirred for 24 h at room
temperature. The solvent was reduced to 5 mL and 20 mL of diethyl
ether were added. The red precipitate was collected by filtration,
washed twice with 10 mL of diethyl ether and recrystallized from
toluene/THF. Yield: 169 mg (0.21 mmol, 85%), red crystals. Anal.
calcd. for C40H35Cl2N2O3PRu (794.67): C, 60.46; H, 4.44; N, 3.53;
found: C, 59.97; H, 4.62; N, 3.37. IR (KBr, cm-1): 2962, 1590, 1505,
1464, 1323, 1226, 1189, 1070, 956, 912, 855, 838, 752, 696, 607,
(4-(2-(1-Methylpyrazol-3-yl))phenyloxy)-3,5-dioxa-4-phospha-
cyclohepta[2,1-a;3,4-a¢]dinaphthalene (4). 330 mg (1.9 mmol) of
2 and 280 mL (2 mmol) of NEt3 were dissolved in 20 mL of dry
THF. This solution was added dropwise to a solution of 700 mg
(2.0 mmol) of 3 in 20 mL of dry THF at 0 ◦C. The reaction mixture
was stirred for 2 h at 0 ◦C. After warming to room temperature, the
resulting suspension was stirred for a further 12 h. A precipitate
formed, which was filtered off, washed with THF and the filtrate
was evaporated in vacuum. The resulting white solid was washed
with 10 mL of diethyl ether and dried in vacuum. Yield: 650 mg
(70%). IR (KBr, cm-1): 2932, 2497, 1462, 1227, 1201, 1071, 953,
562. 1H NMR (600.13 MHz, 25◦C, CDCl3): d 7.97 (d, 1H, 3JHH
=
9.0 Hz), 7.92 (d, 1H, 3JHH = 8.8 Hz), 7.85–7.89 (m, 2H), 7.84 (d,
1H, 3JHH = 9.0 Hz), 7.75 (d, 1H, 3JHH = 8.3 Hz), 7.69 (d, 1H, 3JHH
=
7.4 Hz), 7.58 (d, 1H, 3JHH = 1.7 Hz), 7.41 (t, 1H, 3JHH = 7.5 Hz),
7.38 (t, 1H, 3JHH = 7.3 Hz), 7.32 (d, 1H, 3JHH = 8.8 Hz), 7.27 (d,
1H, 3JHH = 8.6 Hz), 7.19–7.24 (m, 3H), 7.15–7.19 (m, 1H), 7.13 (t,
886, 826, 768, 752, 555. H NMR (400 MHz, 25 ◦C, CDCl3):
d 7.85–8.08 (m, 5H), 7.16–7.62 (m, 12H), 6.63 (d, 1H, JHH
1
3
3
1H, JHH = 7.5 Hz), 6.80 (d, 1H, JHH = 1.9 Hz, H-4pz), 5.59 (d,
3
=
1H, 3JHH = 5.8 Hz, Hcym), 5.30 (d, 1H, 3JHH = 6.0 Hz, Hcym), 5.24
1.8 Hz, H4Pz), 3.99 (s, 3H, CH3). 13C{ H} NMR (150.37 MHz,
25◦C, CDCl3): d 148.9 (d, 2JP,C = 6.9 Hz), 148.0 (d, 2JP,C = 4.2 Hz),
147.4 (s), 147.2 (s), 132.9 (s), 132.7 (s), 131.7 (s), 131.2 (s), 130.8 (s),
130.5 (s), 129.8 (s), 129.2 (s), 128.7 (s), 128.4 (s), 128.3 (s), 127.1 (s),
127.0 (s), 126.4 (s), 126.2 (s), 125.2 (s), 125.0 (s), 124.7 (s), 124.4 (d,
2JP,C = 5.6 Hz), 122.9 (s), 121.82 (s), 121.77 (s), 120.8 (s), 120.7 (s),
1
3
3
(d, 1H, JHH = 6.0 Hz, Hcym), 5.00 (d, 1H, JHH = 5.8 Hz, Hcym),
4.08 (s, 3H, Mepz), 2.80 (sept, 1H, 3J = 6.9 Hz, CH(CH3)2), 1.97
3
(s, 1H, Mecym), 1.16 (d, 3H, CH(CH3)2), 1.11 (d, 3H, J 6.9 Hz,
◦
CH(CH3)2) 13C{ H} NMR (150.37 MHz, 25 C, CDCl3): d 149.6
1
2
2
(d, JPC = 8.3 Hz, CHar), 148.82 (d, JPC = 8.3 Hz, Car), 148.79
(d, 2JPC = 9.7 Hz, Car), 148.1 (s, Car), 133.0 (s, Car), 132.6 (s, Car),
132.0 (s, Car), 131.8 (s, Car), 131.2 (s, CarH), 130.3 (s, CarH), 130.0
(s, 2 ¥ CarH), 129.2 (s, CarH), 128.7 (s, CarH), 128.5 (s, CarH), 127.8
(s, CarH), 127.6 (s, CarH), 126.6 (s, CarH), 126.1 (s, CarH), 125.8
(s, CarH), 125.4 (s, CarH), 125.1 (s, CarH), 124.8 (s, Car), 124.5 (s,
CarH), 123.0 (s, Car), 122.6 (d, 3JPC = 2.8 Hz, CarH), 121.5 (s, CarH),
◦
107.3 (s, C4pz), 39.0 (s, CH3). 31P{ H} NMR (242.94 MHz, 25 C,
1
CDCl3): d 144.8.
Dichlorido[(4-(2-(1-methylpyrazol-3-yl))phenyloxy)-3,5-dioxa-
4-phosphacyclohepta[2,1-a;3,4-a¢]dinaphthalene]palladium(II) (5).
A solution of 125 mg (0.25 mmol) of 3 in 10 mL of CH2Cl2 was
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Table 1 Summary of the crystallographic data and details of data collection and refinement for compounds 5, 6 and 7
5
6
7
Mol. formula
Formula weight
Crystal size (mm)
T (K)
C32H24Cl2N3O3PPd
706.81
0.11 ¥ 0.09 ¥ 0.09
150(2)
1.54184
monoclinic
P21
8.0871(3)
13.8105(5)
13.5808(4)
90
100.325(3)
90
1492.24(9)
2
1.573
7.490
4.60–62.83
16618
C49H47Cl2N2O3.5PRu
922.83
0.30 ¥ 0.30 ¥ 0.21
150(2)
1.54184
tetragonal
P43212
15.80010(10)
15.80010(10)
35.7434(4)
90
C41H36Cl5N2O7PRu
978.01
0.14 ¥ 0.12 ¥ 0.10
150(2)
0.71073
monoclinic
P21
11.4579(2)
15.0138(2)
12.2822(2)
90
100.677(2)
90
2076.29(6)
2
1.564
0.790
3.02–32.51
30506
˚
l (A)
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
a (◦)
b (◦)
g (◦)
90
90
3
˚
V (A )
8923.10(13)
8
1.374
4.636
3.73–62.59
27147
Z
rcalcd (g cm-3)
m (mm-1)
q-range (◦)
Refl. coll.
Indep. refl.
4115 [Rint = 0.0495]
4115/1/381
0.0224, 0.0538
0.0235, 0.0541
1.022
6661 [Rint = 0.0396]
6661/321/622
0.0405, 0.0989
0.0452, 0.1005
1.104
12948 [Rint = 0.0488]
12948/1/518
0.0459, 0.0979
0.0698, 0.1046
0.923
Data/restr./param.
R1, wR2 [I>2s(I)]a
R1, wR2 (all data)b
GooFc
Flack parameter
-0.006(5)
0.251/-0.415
0.033(11)
0.550/-0.507
-0.04(2)
1.026/-0.932
-3
˚
Drmax
/
min
(e A )
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
a R1 = ꢀFo| - |Fcꢀ/ |Fo|. b wR2 = [ w(Fo - Fc2)2/ wFo
]
.
c GooF = [ w(Fo - Fc2)2/(n - p)]1/2
.
2
2
1/2
2
121.1 (s, Car), 110.8 (s, Car), 108.2 (s, C4pz), 104.9 (s, Car), 91.0 (d,
8.6 Hz, Har), 7.15 (d, 1H, 3JHH = 8.7 Hz, Har), 6.48 (d, 1H, 3JHH
=
2
3
2JPC = 6.9 Hz, CcymH), 90.2 (d, JPC = 3.0 Hz, CcymH), 89.4 (d,
2.4 Hz, H4pz), 6.00 (d, 1H, JHH = 5.8 Hz, Hcym), 5.90 (d, 1H,
2JPC = 3.1 Hz, CcymH), 89.1 (s, CcymH), 39.5 (CH3), 30.7 (CH),
3JHH = 6.2 Hz, Hcym), 5.80 (d, 1H, JHH = 5.9 Hz, Hcym), 5.41
3
◦
1
3
22.3 (2 ¥ CH3), 18.7 (CH3). 31P{ H} NMR (242.94 MHz, 25 C,
(d, 1H, JHH = 5.5 Hz, Hcym), 4.51 (s, 3H, NCH3), 2.49 (sept,
CDCl3): d 134.1.
1H, 3JHH = 6.9 Hz, CH(CH3)2), 1.66 (s, 3H, Mecym), 0.94 (d, 3H,
3JHH = 6.9 Hz, CH(CH3)2), 0.71 (d, 3H, 3JHH = 6.9 Hz, CH(CH3)2).
◦
1
13C{ H} NMR (150.37 MHz, 25 C, CDCl3): d 156.2 (s, C), 147.8
(d, 3JPC = 4.3 Hz, C), 147.8 (s, C), 145.3 (s, C), 139.9 (s, CH), 133.7
(s, CH), 133.1 (s, C), 132.2 (s, C), 132.0 (s, CH), 131.7 (s, C), 131.0
(s, CH), 129.9 (s, CH), 128.6 (s, CH), 128.4 (s, CH), 127.6 (s, CH),
127.2 (s, 3xCH), 126.6 (s, CH), 126.5 (s, CH), 126.0 (s, CH), 125.2
(d, 2JPC = 3.3 Hz, C), 124.0 (s, 2xCH), 123.8 (s, CH), 122.8 (s, C),
121.0 (s, CH), 121.0 (s, CH), 114.5 (s, C), 111.1 (s, CH), 107.8 (s,
C), 96.7 (d, 2JPC = 6.9 Hz, CH), 92.6 (d, 2JPC = 7.2 Hz, CH), 90.6
(s, CH), 89.3 (s, CH), 42.9 (s, CH3), 30.6 (s, CH), 22.0 (s, CH3),
Chlorido[(g6-para-cymene)(4-(2-(1-methylpyrazol-3-yl))phenyl-
oxy)-3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4-a¢]dinaphthalene]-
ruthenium(II)perchlorate (7). A solution of 76.5 mg (0.13 mmol)
6
of [(h -para-cymene)RuCl2]2 in 20 mL of acetonitrile was treated
with 52 mg (0.25 mmol) of AgClO4. The colour of the solution
changed from red to yellow. The resulting suspension was stirred
for 2 h at room temperature. The solvent was removed in vacuum,
20 mL of CH2Cl2 were added, the suspension was filtered and
added to 125 mg (0.25 mmol) of 4 dissolved in 10 mL of CH2Cl2.
The mixture was stirred for 12 h at room temperature. During
that time the color changed to orange. The solvent was reduced to
5 mL and 20 mL of diethyl ether were added. The red precipitate
was collected by filtration and washed twice with 10 mL of diethyl
ether. Yield: 195 mg (0.23 mmol, 91%). The major isomer was
isolated by crystallization from CHCl3/n-pentane. Yield: 122 mg
(0.12 mmol, 49%) orange crystals. IR (KBr, cm-1): 3431 (H2O),
3071, 2965, 1617, 1592, 1508, 1464, 1445, 1322, 1223, 1189, 1090
◦
1
21.4 (s, CH3), 18.8 (s, CH3). 31P{ H} NMR (242.94 MHz, 25 C,
CDCl3): d 144.6.
X-Ray structure analyses. Crystal data and refinement pa-
rameters are collected in Table 1. The structures were solved
using direct methods (SIR9224) completed by subsequent differ-
ence Fourier syntheses, and refined by full-matrix least-squares
procedures.25 Semiempirical absorption corrections from equiva-
lents (Multiscan) were carried out.26 All non-hydrogen atoms were
refined with anisotropic displacement parameters. All hydrogen
atoms positions were calculated in ideal positions (riding model).
-
(ClO4 ), 958, 925, 843, 818, 776, 753, 698, 623, 615, 567. In the
1
following only the NMR data of the major isomer are given. H
NMR (600.13 MHz, 25◦C, CDCl3): d 8.25 (d, 1H, 3JHH = 9.0 Hz,
3
Har), 8.04 (d, 1H, JHH = 8.2 Hz, Har), 7.90–7.95 (m, 2H, Har),
3
3
7.88 (d, 1H, JHH = 2.4 Hz, H5pz), 7.83 (d, 1H, JHH = 9.0 Hz,
Har), 7.79 (d, 1H, 3JHH = 8.8 Hz, Har), 7.68 (t, 1H, 3JHH = 7.6 Hz,
Har), 7.50–7.55 (m, 2H, Har), 7.43–7.49 (m, 2H, Har), 7.38 (d, 1H,
Acknowledgements
The authors thank the Deutsche Forschungsgemeinschaft for
financial support of this work.
3JHH = 8.1 Hz, Har), 7.23–7.30 (m, 2H, Har), 7.17 (d, 1H, 3JHH
=
4976 | Dalton Trans., 2009, 4971–4977
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©