Novel synthetic strategy towards the efficient synthesis of substituted bis(pyrazolyl)(2-pyridyl)methane ligands

Article abstract of DOI:10.1002/ejoc.201000198

A general one-pot synthesis of new substituted heteroscorpionate ligands is presented. These mixed-functionality ligands were obtained in a catalyzed Peterson rearrangement starting from the substituted pyrazole, thionyl chloride, and an aldehyde. Thus, the synthesis of polyfunctional tridentate ligands is enabled, and they contain, besides the two pyrazole groups, other functionalities relevant for coordination chemistry. Additionally, the steric hindrance is easily defined in the ligands by the substitution of the pyrazole rings. By combination of the versatility in donor function and steric demand, a systematic tuning of the properties of the bis(pyrazolyl)methane ligands is possible. The synthesis and full characterization of 11 bis(pyrazolyl)methane ligands are reported. Two of these were structurally characterized as well.

Full text of DOI:10.1002/ejoc.201000198

FULL PAPER
DOI: 10.1002/ejoc.201000198
Novel Synthetic Strategy towards the Efficient Synthesis of Substituted
Bis(pyrazolyl)(2-pyridyl)methane Ligands
Alexander Hoffmann,[a] Ulrich Flörke,[b] Markus Schürmann,[a] and Sonja Herres-Pawlis*[a]
Dedicated to Professor Dr. Dr. h. c. Karsten Krohn on the occasion of his retirement
Keywords: N ligands / Ligand design / Heteroscorpionate ligands / Structure elucidation
A general one-pot synthesis of new substituted heteroscor-
pionate ligands is presented. These mixed-functionality li-
gands were obtained in a catalyzed Peterson rearrangement
starting from the substituted pyrazole, thionyl chloride, and
an aldehyde. Thus, the synthesis of polyfunctional tridentate
ligands is enabled, and they contain, besides the two pyr-
azole groups, other functionalities relevant for coordination
chemistry. Additionally, the steric hindrance is easily defined
in the ligands by the substitution of the pyrazole rings. By
combination of the versatility in donor function and steric de-
mand, a systematic tuning of the properties of the bis(pyr-
azolyl)methane ligands is possible. The synthesis and full
characterization of 11 bis(pyrazolyl)methane ligands are re-
ported. Two of these were structurally characterized as well.
Tris(pyrazolyl)methanes can be obtained by reaction of
chloroform with pyrazole and Na2CO3.[3,4] In contrast to
this, bis(pyrazolyl)methanes have to be synthesized by more
complicated reactions: The synthesis of the simplest bis-
(pyrazolyl)methane H2C(pz)2 was first reported by Trofi-
menko as a reaction of pyrazole (Hpz) with CH2Cl2 in an
autoclave at 150 °C.[5] Heteroscorpionate ligands derived
from bis(pyrazolyl)methane have been prepared generally
by two different methods: The first route starts from the
preparation of the N,NЈ-methylenebis(pyrazolyl) system and
subsequent introduction of the third coordinating moiety at
Introduction
The synthesis of bis(pyrazolyl)methanes and their applica-
tion in coordination chemistry and bioinorganic and orga-
nometallic chemistry have been investigated for decades.[1,2]
They convince by their good donor properties, which are
tunable by their substitution patterns, and they show bio-
mimetic character as a result of their resemblance to the
ubiquitously occurring histidine unit. A great disadvantage
is their difficult synthetic access, which limits their general
use in comparison to the related poly(pyrazolyl)borates.
Figure 1. Classical members of the bis(pyrazolyl)methane family.
the methylene bridge.[1,2,6,7] The second route involves the
reaction of two pyrazolyl rings with a reagent carrying the
third coordinating moiety.[1,2,8–14] For example, the reaction
of an N,N,O-heteroscorpionate bearing a 2-hydroxyphenyl
group occurs through reaction of 1,1Ј-carbonylbis(pyr-
azole) with salicylaldehyde.[14]
[a] Institut für Anorganische Chemie II der TU Dortmund,
Otto-Hahn-Str. 6, 44227 Dortmund, Germany
Fax: +49-231-755-5048
E-mail: sonja.herres-pawlis@tu-dortmund.de
[b] Department Chemie der Universität Paderborn,
Warburger Str. 100, 33098 Paderborn, Germany
4136
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 4136–4144

Efficient Synthesis of Substituted Bis(pyrazolyl)(2-pyridyl)methane Ligands
In this way, polyfunctional tridentate ligands containing aldehyde to form the desired bis(pyrazolyl)methane ligand.
two substituted pyrazolyl groups were synthesized that also This one-pot synthesis involves the reaction of the pyrazole
incorporate other coordinationally relevant groups like phe- with NaH and SOCl2 and then with the desired third li-
nols or pyridines (Figure 1). Thiols or carboxylates are also gand. At first, the sulfoxide compound is formed in situ.
possible.
Without any further purification, the sulfoxide compound
In spite of these intense efforts, an efficient generally ap- reacts with the aldehyde to form the desired ligand and
plicable route to substituted bis(pyrazolyl)methanes is lack- SO2, whereat cobalt(II) chloride acts as catalyst. We have
ing. Some substituted bis(pyrazolyl)methanes have been re- found that the use of thionyl chloride instead of phosgene
ported,[12–14] but the synthetic parameters had to be opti- in this step provides a more efficient route with yields up to
mized for each case in a time-consuming process. In this 90%. Considering the green aspects of this chemistry, this
paper, we report on the synthesis and characterization of method is favorable over the use of phosgene. Scheme 1
11 new bis(pyrazolyl)methane ligands and describe a gene- shows the reaction by using the example of pyridine-2-carb-
ral and efficient one-pot synthesis for heteroscorpionate li- aldehyde and 3-phenylpyrazole (3-Phpz).
gands with substituted pyrazoles.
Results and Discussion
Ligand Synthesis
The syntheses of heteroscorpionate ligands from bis(pyr-
azolyl)methanes and phenols or substituted phenols are
known,[14–16] but, in these syntheses phosgene is used or the
yields are moderate. Carrano et al.[13,14] have also synthe-
sized bis(pyrazolyl)methanes of substituted pyrazoles with
phenol as a third ligand, but the synthetic conditions must
be varied for each substituted pyrazole or the reaction takes
a long time (more than 24 h). Additionally, the aldehyde
has to be added in great excess, which has to be removed
after the reaction. Burzlaff et al.[8] published in 2009 a syn-
thesis of an enantiopure N,N,O scorpionate ligand with
Scheme 1. Synthesis of L4.
camphorpyrazole and thionyl chloride on the basis of the
In this report, pyridine-2-carbaldehyde, quinoline-2-car-
results originally reported by Reger et al.[12,17] This method baldehyde, salicylaldehyde, and benzoyl pyridine are used
is based on a modified Peterson rearrangement during the as the aldehyde component and 3-phenylpyrazole (3-Phpz),
reaction of aldehydes and 1,1Ј-sulfinylbis(pyrazole).
3-tert-butylpyrazole (3-tBupz), and 3-mesitylpyrazole (3-
Herein we present a one-pot synthesis of bis(pyrazolyl)- Mspz) are used as substituted pyrazoles. The reaction suc-
methanes. A general synthetic strategy for bis(pyrazolyl)- ceeded with all mentioned aldehydes and yielded the follow-
methanes with pyridine as the third ligand and substituted ing new ligands in good yields (Scheme 2).
pyrazoles is reported for the first time. The ligands were
Reger et al.[12,19] applied this condensation chemistry to
synthesized by following a general procedure that allows the ketones. In our studies, we found that only 3-Phpz of the
modified Peterson reaction of substituted pyrazoles with an substituted pyrazoles reacts with the ketone benzoyl pyr-
Scheme 2. Overview of the synthesized ligands.[18]
Eur. J. Org. Chem. 2010, 4136–4144
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4137

A. Hoffmann, U. Flörke, M. Schürmann, S. Herres-Pawlis
FULL PAPER
idine to new ligand L13 (Scheme 3). Remarkably, the reac- Crystal Structure
tion of this ketone with the two other substituted pyrazoles
To discuss the structural features of the diverse ligands,
(3-tBupz and 3-Mspz) does not occur because the sterically
demanding groups (tert-butyl and mesityl) probably hinder
the reaction.
we chose two crystal structures for a closer look: The struc-
ture of L4 exhibits properties typical of heteroscorpionate
ligands with pyridine as the third ligand, whereas L6 has a
phenol as the third ligand. Single crystals of L4 were ob-
tained by slow crystallization of a saturated methanol/ace-
tonitrile solution over a few days and those of L6 where
obtained from a saturated methanol solution. The results
of the structure analyses are shown in Figures 2 and 3, and
selected bond lengths and angles are collected in Table 2;
parameters related to data collection and refinement are
listed in Table 3.
Scheme 3. Synthesis of L13.
This synthesis protocol allows systematic tuning of the
properties of the bis(pyrazolyl)methane ligands. By combin-
ing the different substituted pyrazoles with the third ligand
(e.g., pyridine, quinoline, thiol, phenol, etc.), a library of
bis(pyrazolyl)ligands could be built up. By the thionyl chlo-
ride method, a multitude of bis(pyrazolyl)methane ligands
with substituted pyrazoles is easily accessible.
Figure 2. Molecular structure of L4.
NMR Spectroscopy
The chemical shifts of the Capical–H atom are listed in
Table 1.[20] In ligands with pyridine as the third coordinat-
ing moiety, the peak of the Capical–H atom appears at higher
field than in ligands with quinoline as a third coordinating
moiety. According to that, the electron density at the
C
apical–H atom in ligands with pyridine as the third ligand
is higher. Surprisingly, the position of the Capical–H signals
of the ligands with pyrazolyl and with phenylpyrazolyl as
the pyrazolyl moiety is similar. Also, the signals of the li-
gands with tert-butylpyrazolyl and mesitylpyrazolyl are
similar. The shifts of the ligands with phenol as the third
ligand show no consistent trend. Upon closer inspection of
the Capical–H signal of the different substituted pyrazoles,
the following trends can be derived: The HC(3-Phpz)2(x)
ligands show the Capical–H shift at the lowest field. The sig-
nals of the unsubstituted pyrazolyl ligands appear at higher
field. The ligands with more demanding substituents like
mesityl or tert-butyl show the signal at even higher field.
Figure 3. Molecular structure of L6.
The characteristic bond lengths and angles of both struc-
tures are virtually the same. The selected bond lengths and
angles are in good agreement with comparable molecules,
for example, the bond lengths and angles of L4 do not differ
significantly from those in bis(indazol-1-yl)pyridin-2Ј-
ylmethane [Cap–Npz 1.444(3)/1.452(3) Å; Cap–Carom
1.524(3) Å; Npz–Cap–Carom 112.3(2)/113.8(2)°; Npz–Cap–
Npz 112.2(2)°].[21] Also, the characteristic parameters of L6
do not differ from those of heteroscorpionate ligands with
phenol or substituted phenol as the third ligand: Cap–Npz
1.466/1.467 Å[11] or 1.462(8)/1.463(7) Å[14] or 1.465/
Table 1. 1H NMR spectroscopic shifts of the Capical–H atom in
CDCl3.[20]
δ [ppm]
x = qu
x = py
x = phOH
HC(pz)2(x)
7.74
7.79
7.32
7.32
7.90
7.97
7.50
7.45
7.57
7.87
7.39
7.68
HC(3-Phpz)2(x)
HC(3-tBupz)2(x)
HC(3-Mspz)2(x)
4138
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 4136–4144

Efficient Synthesis of Substituted Bis(pyrazolyl)(2-pyridyl)methane Ligands
Table 2. Selected bond lengths and angles of the molecules in crys- these planes is calculated to be 3.732 Å. In L6, an intermo-
tals of L4 and L6 and comparison to DFT calculated values.
lecular hydrogen-bond interaction between the phenol H
DFT[a]
L6
DFT[a]
atom to the pyrazole N atom of another molecule is pres-
ent. The distance between the N atom and the H atom is
1.985(11) Å and is in accordance with other N···H hydrogen
bonds.[22,23]
L4
Bond lengths [Å]
Cap–Npz
1.444(2) 1.454 1.443(5) 1.449
1.464(2) 1.466 1.467(5) 1.465
1.362(2) 1.352 1.360(4) 1.353
1.361(2) 1.348 1.363(4) 1.349
1.513(2) 1.521 1.528(5) 1.528
Npz–Npz
Cap–Carom
Bond angles [°]
Npz–Cap–Npz
Npz–Cap–Carom
108.7(2) 109.7 107.2(3) 110.2
111.8(2) 111.8 112.4(3) 112.7
112.5(2) 112.6 110.3(4) 111.4
Twist angles [°]
Phenyl vs. pyrazolyl
11.2
1.3
83.6
86.6
87.3
2.5
0.5
89.9
80.3
88.6
36.0
37.4
88.9
81.0
77.3
0.3
3.8
89.3
84.8
87.9
Pyrazolyl vs. pyrazolyl
Third ligand vs. pyrazolyl
[a] Gaussian03, B3LYP/6-31g(d).
Table 3. Crystallographic data for L4 and L6.
L4
L6
Figure 4. Crystal packing of L4.
Molecular Mass
Empirical formula
Molecular Mass
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
377.44
392.45
C24H19N5
377.44
monoclinic
P21/n
13.7336(11)
5.5628(4)
25.362(2)
C25H20N4O
392.45
Guided by the idea that the twist between the pyrazolyl
rings and the phenyl rings is crucial for intermolecular
packing, we performed gas-phase DFT calculations on the
structural properties of L4 and L6 (Table 2). These calcula-
tions reproduce the bond lengths and angles very well, but
the predicted twist between the pyrazolyl and the phenyl
rings for both ligands is too small. The energy difference
between the DFT-optimized structures and the twisted
structures found in the solid state is 0.02 kcal/mol for L4
and 0.33 kcal/mol for L6. These energy differences are be-
low the range of the accuracy of DFT calculations at that
theoretical level. Hence, the potential energy surface is rela-
tively flat for the twist between the pyrazolyl and phenyl
rings such that the twist is highly influenced by packing
effects and normally occurring weak intermolecular interac-
tions like H bonds.
triclinic
¯
P1
8.8020(10)
10.6835(13)
11.2411(14)
75.394(3)
76.988(3)
87.152(3)
996.2(2)
2
1.308
412
120(2)
27.88
104.509(9)
γ [°]
V [Å3]
1875.8(3)
4
1.337
792
173(1)
25.50
6873
3491
0.0348
0.0551
Z
Dcalcd. [gcm–3]
F(000)
Temperature [K]
Θmax [°]
Reflections collected
Independent reflections
R1 [IՆ2σ(I)]
wR2 (all data)
7899
4724
0.0524
0.1246
Largest diff. peak/hole [eÅ–3] 0.160/–0.201
0.238/–0.237
1.461 Å;[13] Cap–Carom 1.518 Å[11] or 1.515(11) Å[14] or
1.514 Å;[13] Npz–Cap–Cpz 110.01°[11] or 109.3(5)°[14] or
111.11°;[13] Npz–Cap–Carom 113.21/116.19°[11] or 112.0(5)/
114.2(5)°[14] or 111.62/113.53°.[13]
Conclusions
In summary, we report on an efficient method for the
A closer consideration of the twist angles in the crystal general synthesis of substituted bis(pyrazolyl)methanes.
structures reveals interesting features: in L4, the phenyl This method makes use of thionyl chloride instead of phos-
rings of the substituted pyrazolyl functions are nearly in gene and allows the combination of various substituted pyr-
plane with the pyrazolyl rings (11.2/1.3°) and thus less azoles with different aldehydes. By connecting different sub-
twisted against the pyrazolyl rings than in L6 (36.0/37.4°). stituted pyrazoles with the third ligand function, a library
The fact that the phenyl and pyrazolyl rings are in plane of bis(pyrazolyl)methane ligands could be built up. This ad-
results from π stacking of the molecules. It is apparent from vantageous synthetic protocol enables systematic tuning of
the unit cell that pairs of molecules orientate one of their the properties of the bis(pyrazolyl)methane ligands and has
phenyl-pyrazolyl units in the opposite direction to each been optimized towards overall yields in the range of 55–
other such that π interactions between the aromatic systems 95%. Furthermore, two ligands were structurally charac-
of two of these units can occur (Figure 4). The distance of terized and an interesting packing effect was identified.
Eur. J. Org. Chem. 2010, 4136–4144
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4139

A. Hoffmann, U. Flörke, M. Schürmann, S. Herres-Pawlis
FULL PAPER
tures of L4, L6, and their counterparts with fixed angles were com-
puted by using the B3LYP functional and a 6-311+g(d) basis set.
Experimental Section
Materials and Methods: All manipulations involving air- and moist-
ure-sensitive compounds were carried out by using standard
Schlenk techniques. The solvents were purchased from commercial
sources. THF was freshly distilled from sodium/potassium and
benzophenone prior to use. Sodium hydride (95%, Sigma Aldrich),
thionyl chloride (Fluka), pyridine-2-carbaldehyde (99%, Alfa
Aesar), quinoline-2-carbaldehyde (97%, Alfa Aesar), salicylaldehyde
(99%, Alfa Aesar), benzoyl aldehyde (99%, Alfa Aesar), pyrazole
(98%, Alfa Aesar), and anhydrous CoCl2 (98%, Aldrich) were used
as purchased. The substituted pyrazoles were synthesized according
to published procedures: 3-Phpz,[24] 3-tBupz,[24] and 3-Mspz.[25]
General Synthesis of Heteroscorpionate Ligands L1–L12: NaH
(2.4 g, 100 mmol) was suspended in freshly distilled THF (100 mL)
and stirred at 0 °C. The relevant pyrazole (100 mmol) was added
gradually to the suspension over 15 min and the stirring was con-
tinued at 0 °C until gas evolution stopped (ca. 30 min.). Then, thio-
nyl chloride (3.7 mL, 50 mmol) was added dropwise to this pale-
colored solution at 0 °C. After stirring for additional 45 min at 0 °C
and then 30 min at room temperature, the desired aldehyde
(50 mmol) and a catalytic amount of cobalt(II) chloride were
added, and the reaction mixture was heated under vigorous stirring
at reflux overnight. During this time period the mixture turned
intensely colored and evolution of SO2 was observed. Some ligands
were carefully heated because the mixture can develop foam in
great amounts. The reaction mixture was allowed to cool to room
temperature before diethyl ether (50 mL) and water (100 mL) were
gradually added. The biphasic solution was then stirred for 1 h.
The layers were separated, and the aqueous phase was extracted
with diethyl ether (3ϫ60 mL). The combined organic phase was
washed with distilled water, dried with sodium sulfate and filtered.
The solvent was then removed in vacuo, and the resulting solid was
suspended in hexane. This flask was placed in an ultrasound bath
to break up the lumps that had formed, yielding a solid. This solid
was collected by filtration, washed efficient with hexane and dried
in vacuo.
Physical Measurements: NMR spectra were recorded with a Bruker
Avance 500 spectrometer. The NMR signals were calibrated to the
residual signals of the deuterated solvents (CDCl3 δH = 7.26 ppm).
These assignments were confirmed by standard Bruker gradient
enhanced HMBC, HMQC, SELTOCSY, and INAPT pulse se-
quences. IR spectra were recorded with a Nicolet P510. Mass spec-
tra in the EI (70 eV) and ESI modes were recorded with a Finnigan
MAT 40 and a Finnigan TSQ instrument, respectively. Elemental
analyses were recorded with a Perkin–Elmer analyzer Model 2400.
Crystal Structure Analyses: Crystal data for compounds L4 and L6
are presented in Tables 2 and 3. Data for L4 was collected with an
Xcalibur S Diffractometer from Oxford Diffraction with graphite-
monochromated Mo-Kα radiation. The data collection covered al-
most the whole sphere of reciprocal space with 8 sets at different
κ-angles and 430 frames with ω-rotation (∆/ω = 1°) at two times
60 s per frame. The crystal-to-detector distance was 4.5 cm. Crystal
decay was monitored by repeating the initial frames at the end of
data collection. Analyzing the duplicate reflections showed that
there was no indication for any decay. The structure was solved by
direct methods with SHELXS97[26] and successive difference Fou-
rier syntheses. Refinement applied full-matrix least-squares meth-
ods SHELXL97.[27] The hydrogen atoms were placed in geometri-
cally calculated positions using a riding model with Uiso con-
strained 1.2 times Ueq for the carrier atom. Atomic scattering fac-
tors for neutral atoms and real imaginary were taken from Inter-
national Tables for X-ray Crystallography.[28] The figure was cre-
ated by SHELXTL.[29] Data for L6 was collected with a Bruker-
AXS SMART[30] APEX CCD by using Mo-Kα radiation (λ =
0.71073 Å) and a graphite monochromator. Data reduction and ab-
sorption correction was performed with SAINT and SADABS.[30]
The structure was solved by direct and conventional Fourier meth-
ods and all non-hydrogen atoms refined anisotropically with full-
matrix least-squares based on F2 (SHELXTL[30]). Hydrogen atoms
were derived from difference Fourier maps and placed at idealized
positions, riding on their parent C atoms, with isotropic displace-
ment parameters Uiso(H) = 1.2Ueq(C) and 1.5Ueq(C methyl). All
methyl groups were allowed to rotate but not to tip.
(2-Pyridinyl)bis(pyrazolyl)methane (pz)2(py)CH (L1):[18] Following
the general synthesis, pyrazole (6.8 g, 100 mmol) and pyridine-2-
carbaldehyde (4.8 mL, 50 mmol) were used. The final product was
obtained as yellow-orange solid (10.6 g, 95%). M.p. 56 °C. 1H
NMR (500 MHz, CDCl3, 25 °C): δ = 6.34 [t, JH,H = 2.1 Hz, 2 H,
4-H (pz)], 7.05 [d, JH,H = 7.6 Hz, 1 H, 3-H (py)], 7.29 [dd, JH,H
=
4.8, 7.6 Hz, 1 H, 5-H (py)], 7.63 [d, JH,H = 1.6 Hz, 2 H, 5-H (pz)],
7.64 [d, JH,H = 2.2 Hz, 2 H, 3-H (pz)], 7.72 [t, JH,H = 7.7 Hz, 1 H,
4-H (py)], 7.74 (s, 1 H, CH), 8.64 [d, JH,H = 1.6, 4.7 Hz, 1 H, 3-H
(py)] ppm. 13C NMR (125 MHz, CDCl3, 25 °C): δ = 78.5
[C(pz)2(py)], 106.7 [4-C(pz)], 122.2 [3-C(py)], 123.9 [5-C(py)], 129.9
[5-C(pz)], 137.2 [4-C(py)], 140.8 [3-C (pz)], 149.7 [6-C(py)], 154.8
[2-C(py)] ppm. IR (KBr): ν = 3139 (w), 3110 (w, νCH), 3054 (vw,
˜
νCH), 3012 (vw, νCH), 2960 (vw, νCH), 2717 (vw), 2678 (vw), 2601
(vw), 2547 (vw), 1972 (vw), 1778 (vw), 1731 (vw), 1646 (w), 1589
(m), 1572 (w), 1508 (m), 1477 (w), 1465 (w), 1454 (vw), 1430 (s),
1390 (vs). 1363 (w), 1346 (w), 1321 (m), 1298 (m), 1286 (m), 1261
(w), 1241 (vw), 1216 (w), 1191 (w), 1172 (vw), 1149 (vw), 1085 (s),
1057 (m), 1045 (m), 997 (w), 974 (w), 964 (w), 916 (w), 896 (vw),
873 (m), 840 (w), 813 (m), 804 (m), 786 (s), 773 (s), 752 (vs, νCH),
734 (m), 678 (w), 647 (m), 620 (w), 608 (w), 493 (vw) cm–1. MS
(EI): m/z (%) = 225.1 (40) [M+ = C12H11N5], 159.1 (18), 158.1 (100)
[C9H8N3+], 147.1 (82) [C7H7N4+], 131.1 (38), 118.1 (16), 79.1 (8),
78.1 (29) [C5H4N+], 67.1 (5) [C3H3N2+]. C12H11N5 (225.1): calcd.
C 63.99, H 4.92, N 31.09; found C 64.03, H 4.96, N 30.90.
CCDC-765253 (for L4) -762957 (for L6) contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
(2-Quinolinyl)bis(pyrazolyl)methane (pz)2(qu)CH (L2): Following
the general synthesis, pyrazole (6.8 g, 100 mmol) and quinoline-2-
carbaldehyde (7.9 g, 50 mmol) were used. The final product was
obtained as a dark-orange solid (11.7 g, 85%). M.p. 78 °C. 1H
NMR (500 MHz, CDCl3, 25 °C): δ = 6.36 [t, JH,H = 2.2 Hz, 2 H,
Computational Details: Density functional theory (DFT) calcula-
tions were performed with the program suite Gaussian 03.[31] The
geometries of L4 and L6 were optimized (Table 2) by using the
B3LYP[32] hybrid DFT functional and the 6-31g(d) basis sets im-
plemented in Gaussian on all atoms. Tight conversion criteria were
applied. The starting geometries were generated from the crystal
structures. Frequency calculations confirmed the stationary points
to be minima. Electronic energies for gas-phase-optimized struc-
4-H (pz)], 7.29 [d, JH,H = 7.5 Hz, 1 H, 3-H (qu)], 7.56 [t, JH,H
=
7.4 Hz, 1 H, 7-H(qu)], 7.64 [d, JH,H = 1.8 Hz, 2 H, 3-H (pz)], 7.70
[d, JH,H = 2.5 Hz, 1 H, 5-H (pz)], 7.72 [m, 1 H, 8-H(qu)], 7.82 [d,
JH,H = 8.2 Hz, 1 H, 6-H(qu)], 7.90 (s, 1 H, CH), 8.07 [d, JH,H
=
7.6 Hz, 1 H, 9-H(qu)], 8.19 [d, JH,H = 8.5 Hz, 1 H, 4-H(qu)] ppm.
13C NMR (125 MHz, CDCl3, 25 °C): δ = 79.1 [C(pz)2(qu)], 106.6
4140
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 4136–4144

Efficient Synthesis of Substituted Bis(pyrazolyl)(2-pyridyl)methane Ligands
[4-C(pz)], 119.5 [3-C(qu)], 127.4 [7-C(qu)], 127.5 [6-C(qu)], 127.8
[5-C(qu)], 129.7 [9-C(qu)], 130.0 [8-C(qu)], 130.1 [5C(pz)], 137.4 [4-
C(qu)], 140.9 [3-C(pz)], 147.5 [10-C(qu)], 154.5 [2-C(qu)] ppm. IR
νCH ), 3058 (w, νCH ), 3031 (vw, νCH ), 2923 (vw, νCH ),
arom arom arom aliph
1953 (vw), 1889 (vw), 1810 (vw), 1772 (vw), 1754 (vw), 1700 (vw),
1652 (vw), 1585 (w), 1560 (vw), 1529 (vw), 1498 (m), 1455 (m),
(KBr): ν = 3131 (w), 3114 (w, νCH), 3068 (vw, νCH), 3019 (vw, νCH), 1432 (w), 1382 (vw), 1355 (w), 1323 (vw), 1301 (vw), 1270 (vw),
˜
2992 (vw, νCH), 2655 (vw), 2362 (vw), 2138 (vw), 1978 (vw), 1949
(vw), 1864 (vw), 1833 (vw), 1737 (vw), 1712 (vw), 1617 (w, νCN), (vw), 993 (vw), 948 (vw), 937 (vw), 916 (vw), 898 (vw), 869 (w),
1589 (m, νCN), 1560 (vw), 1538 (vw), 1504 (s), 1459 (vw), 1438 (w), 750 (vs), 694 (vs), 657 (vw), 619 (vw), 505 (vw), 468 (vw), 444 (vw),
1205 (m), 1151 (vw), 1099 (w), 1074 (m), 1049 (m), 1026 (vw), 1011
1428 (m), 1394 (s), 1374 (m), 1347 (m), 1329 (vw), 1314 (m), 1305 428 (vw), 416 (vw), 408 (vw) cm–1. MS (EI): m/z (%) = 377.1 (3)
(s), 1299 (s), 1260 (w), 1213 (m), 1189 (w), 1170 (w), 1155 (vw),
1139 (vw), 1122 (w), 1108 (vw), 1087 (s), 1059 (m), 1049 (m), 1014
(vw), 991 (vw), 973 (m), 961 (w), 954 (w), 920 (w), 902 (m), 880
[M+ = C24H19N5+], 279.2 (5), 235.1 (11), 234.1 (16) [M+ – C9H7N2],
167.1 (10), 157.1 (5), 145.1 (9) [C7H5N4+], 144.1 (100), 143.1 (119)
[C9H7N2+], 118.1 (39), 117.1 (10), 116.1 (4), 115.1 (14), 113.1 (3),
(w), 856 (w), 846 (w), 819 (s, νCH), 797 (s), 792 (s), 781 (s), 769 (vs, 105.1 (6), 104.1 (3), 92.0 (2), 91.0 (3), 90.0 (7), 89.0 (7), 78.0 (3),
νCH), 745 (s), 666 (w), 651 (w), 626 (m), 619 (m), 585 (w) cm–1. MS [C5H4N+], 77.0 (14), 71.1 (5), 70.1 (4), 69.1 (2). C24H19N5 (377.1):
(EI): m/z (%) = 275.1 (66) [M+ = C16H13N5+], 274.1 (14) [M+ – H], calcd. C 76.37, H 5.07, N 18.55; found C 76.07, H 5.00, N 18.17.
209.1 (22), 208.1 (100), [M+ – C3H3N2], 207.1 (16), 181.1 (39), 168.1
(2-Quinolinyl)bis(3-phenylpyrazolyl)methane (3-Phpz)2(qu)CH (L5):
Following the general synthesis, 3-phenylpyrazole (14.4 g,
(8), 154.1 (7), 147.1 (44) [C7H7N4+], 129.1 (24), 128.1 (22)
[C9H6N+], 101.1 (7), 77.0 (7), 67.0 (3) [C3H3N2+]. C16H13N5
100 mmol) and quinoline-2-carbaldehyde (7.9 g, 50 mmol) were
(275.1): calcd. C 69.80, H 4.76, N 25.44; found C 69.43, H 4.87, N
used. The final product was obtained as a brown solid (15.7 g,
25.37.
1
73%). M.p. 122 °C. H NMR (500 MHz, [D6]acetone, 25 °C): δ =
(2-Hydroxyphenyl)bis(pyrazolyl)methane (pz)2(phOH)CH (L3):[18] 6.83 [d, JH,H = 2.5 Hz, 2 H, 4-H (3-Phpz)], 7.29 [t, JH,H = 7.3 Hz,
Following the general synthesis, pyrazole (6.8 g, 100 mmol) and sal-
icylaldehyde (5.3 mL, 50 mmol) were used. The final product was
obtained as yellow-orange solid (22.1 g, 91%). M.p. 140 °C. 1H
NMR (500 MHz, [D6]acetone, 25 °C): δ = 6.32 [t, JH,H = 2.6 Hz,
2 H, 4-H (pz)], 6.89 [t, JH,H = 7.5 Hz, 1 H, 4-H (phOH)], 6.98 [d,
JH,H = 8.5 Hz, 1 H, 6-H (phOH)], 7.11 [d, JH,H = 7.5 Hz, 1 H, 3-
H (phOH)], 7.28 [t, JH,H = 8.5 Hz, 3 H, 5-H (phOH)], 7.56 [d, JH,H
= 1.4 Hz, 2 H, 3-H (pz)], 7.67 [d, JH,H = 2.6 Hz, 2 H, 2-H (pz)],
2 H, p-H (3-Phpz)], 7.36 [t, JH,H = 7.5 Hz, 4 H, m-H (3-Phpz)],
7.53 [d, JH,H = 8.7 Hz, 1 H, 3-H (qu)], 7.61 [t, JH,H = 7.6 Hz, 1 H,
7-H(qu)], 7.77 [t, JH,H = 7.5 Hz, 1 H, 8-H(qu)], 7.84 [d, JH,H
7.3 Hz, 4 H, o-H (3-Phpz)], 7.97 [m, 1 H, 6H(qu)], 8.02 [d, JH,H
=
=
8.5 Hz, 1 H, 9-H(qu)], 8.07 [d, JH,H = 2.4 Hz, 2 H, 5-H (3-Phpz)],
8.13 (s, 1 H, CH), 8.40 [d, JH,H = 8.4 Hz, 1 H, 4-H(qu)] ppm. 13C
NMR (125 MHz, [D6]acetone, 25 °C): δ = 80.0 [C(3-Phpz)2(qu)],
104.5 [4-C (3-Phpz)], 120.7 [3-C (qu)], 126.4 [o-C(3-Phpz)], 128.2
7.99 (s, 1 H, CH), 9.65 [br., 1 H (phOH)] ppm. 13C NMR [7-C(qu)], 128.6 [p-C(3-Phpz)], 128.7 [6-C(qu)], 128.7 [5-C(qu)],
(125 MHz, [D6]acetone, 25 °C): δ = 74.3 [C(pz)2(phOH)], 105.5 [4-
C (pz)], 116.4 [6-C (phOH)], 119.6 [4-C (phOH)], 122.7 [3-C
(phOH)], 129.0 [3-C (phOH)], 129.6 [5-C(pz)], 130.7 [5-C(phOH)],
129.3 [m-C(3-Phpz)], 130.2 [9-C(qu)], 130.9 [8-C(qu)], 132.9 [5-C
(3-Phpz)], 134.2 [Cph (3-Phpz)], 138.2 [4-C(qu)], 148.2 [10-C(qu)],
153.0 [Cpz (3-Phpz)], 156.0 [2-C (py)] ppm. IR (KBr): ν = 3106 (vw,
˜
139.8 [3-C (pz)], 154.9 [1-C (phOH)] ppm. IR (KBr): ν = 3145 (vw,
νCH ), 3058 (vw, νCH ), 3001 (vw, νCH ), 2956 (vw, νCH ),
˜
arom
arom
aliph
νCH ), 3126 (vw, νCH ), 3110 (vw, νCH ), 3097 (vw, νCH ), 2925 (vw, νCH ), 1955ar(ovmw), 1617 (vw), 1594 (w), 1563 (vw), 1527
arom
aliph
2958 (vw, νCH ), 2865ar(ovmw, νCH ), 2721 a(rwom), 2695 (w), 2591a(rowm),
(vw), 1500 (vs), 1455 (s), 1428 (vw), 1415 (vw), 1400 (vw), 1378
aliph
aliph
2460 (w), 1608 (m), 1506 (m), 1461 (vs), 1434 (w), 1401 (s), 1367
(w), 1349 (m), 1320 (m), 1307 (s), 1295 (s), 1267 (m), 1243 (w),
1233 (w), 1223 (w), 1201 (w), 1180 (w), 1159 (vw), 1104 (w), 1087
(vw), 1355 (w), 1340 (vw), 1326 (vw), 1303 (w), 1281 (vw), 1236
(m), 1213 (w), 1176 (vw), 1151 (vw), 1141 (vw), 1118 (vw), 1099
(vw), 1074 (m), 1049 (w), 1027 (vw), 1015 (vw), 998 (vw), 946 (vw),
(s), 1056 (s), 1044 (m), 979 (w), 963 (vw), 916 (vw), 873 (s), 866 906 (w), 872 (vw), 852 (vw), 808 (s), 790 (w), 781 (w), 752 (vs), 694
(m), 813 (w), 798 (m), 776 (m), 759 (vs), 751 (vs), 661 (vw), 653 (vs), 667 (vw), 619 (vw), 557 (vw), 522 (vw), 480 (vw), 418 (vw)
(vw), 626 (m), 607 (vw), 548 (vw), 538 (vw), 466 (vw) cm–1. MS cm–1. MS (EI): m/z (%) = 427.3 (60) [M+ = C28H21N5+], 377.2 (4),
(EI): m/z (%) = 240.1 (13) [M+ = C13H12N4O+], 173.1 (18) [M+
–
300.3 (3), 299.2 (9) [M+ – C9H6N], 288.2 (3), 286.3 (12), 285.2 (82),
284.2 (100) [M+ – C9H7N2], 283.2 (7), 282.2 (4), 281.2 (3), 270.2
(6), 248.2 (10), 247.2 (3), 242.2 (6), 245.2 (9), 244.2 (3), 217.2 (4),
216.2 (2), 182.1 (3), 181.7 (7), 180.1 (2), 167.1 (5), 157.2 (25), 156.1
(5) [C10H8N2+], 155.1 (6), 154.1 (4), 144.1 (55), 143.1 (8)
[C9H7N2+], 142.1 (7), 130.1 (6), 129.1 (15), 128.1 (39) [C9H6N+],
127.1 (4), 119.1 (6), 118.1 (2), 117.1 (6), 116.1 (6), 115.1 (15), 106.1
(3), 105.1 (21), 104.1 (3), 103.1 (6), 102.1 (5), 101.1 (5), 91.1 (3),
90.1 (4), 89.1 (6), 77.1 (25) [C6H5+]. C28H21N5 (427.1): calcd. C
78.67, H 4.95, N 16.38; found C 78.47, H 5.00, N 16.07.
C3H3N2], 172.1 (100), 171.1 (6), 167.1 (6), 146.1 (6) [C7H6N4+],
145.1 (62), 144.1 (19), 143.1 (5), 119.1 (9), 118.1 (12), 117.1 (6),
105.1 (5), 92.1 (5) [C5H5O+], 91.1 (7), 90.1 (3), 77.1 (8), 68.1 (11)
[C3H4N2+]. C13H12N4O (240.1): calcd. C 64.99, H 5.03, N 23.32;
found C 64.59, H 5.08, N 23.27.
(2-Pyridinyl)bis(3-phenylpyrazolyl)methane (3-Phpz)2(py)CH (L4):
Following the general synthesis, 3-phenylpyrazole (14.4 g,
100 mmol) and pyridine-2-carbaldehyde (4.8 mL, 50 mmol) were
used. The final product was obtained as pale-brown solid (12.7 g,
1
74%). M.p. 160 °C. H NMR (500 MHz, [D6]acetone, 25 °C): δ =
(2-Hydroxyphenyl)bis(3-phenylpyrazolyl)methane (3-Phpz)2(phOH)-
6.83 [d, JH,H = 2.4 Hz, 2 H, 4-H (3-Phpz)], 7.32 [t, JH,H = 7.4 Hz, CH (L6): Following the general synthesis, 3-phenylpyrazole (14.4 g,
2 H, p-H (3-Phpz)], 7.39 [m, 4 H, o-H (3-Phpz)], 7.42 [m, 5 H, 3- 100 mmol) and salicylaldehyde (5.3 mL, 50 mmol) were used. The
H (py)], 7.45 [dd, JH,H = 4.5, 7.4 Hz, 1 H, 5-H (py)], 7.87 [d, JH,H final product was obtained as pale-brown solid (15.1 g, 77%). M.p.
= 8.6 Hz, 4 H, o-H (3-Phpz)], 7.90 [t, JH,H = 7.8 Hz, 1 H, 4-H (py)],
7.96 (s, 1 H, CH), 7.99 [d, JH,H = 2.5 Hz, 2 H, 5-H (3-Phpz)], 8.65
130 °C. 1H NMR (500 MHz, [D6]acetone, 25 °C): δ = 6.76 [d, JH,H
= 2.5 Hz, 2 H, 4-H (3-Phpz)], 6.91 [t, JH,H = 7.4 Hz, 1 H, 4-H
[dd, JH,H = 1.7, 4.6 Hz, 1 H, 6-H (py)] ppm. 13C NMR (125 MHz, (phOH)], 7.01 [dd, JH,H = 1.0, 8.3 Hz, 1 H, 6-H (phOH)], 7.25 [dd,
[D6]acetone, 25 °C): δ = 78.8 [C(3-Phpz)2(py)], 103.5 [4-C (3-Phpz)],
122.4 [3-C (py)], 124.0 [5-C (py)], 125.5 [o-C(3-Phpz)], 127.7 [p-C(3-
Phpz)], 128.5 [m-C(3-Phpz)], 131.8 [5-C (3-Phpz)], 133.3 [Cph (3-
Phpz)], 137.2 [4-C (py)], 149.4 [6-C (py)], 152.0 [Cpz (3-Phpz)],
JH,H = 1.5, 8.0 Hz, 1 H, 3-H (phOH)], 7.28 [m, 2 H, p-H (3-Phpz)],
7.32 [m, 1 H, 5-H (phOH)], 7.37 [t, JH,H = 7.4 Hz, 4 H, m-H (3-
Phpz)], 7.77 [d, JH,H = 2.5 Hz, 2 H, 5-H (3-Phpz)], 7.83 [d, JH,H
=
8.3 Hz, 4 H, o-H (3-Phpz)], 8.04 (s, 1 H, CH) ppm. 13C NMR
(125 MHz, [D6]acetone, 25 °C): δ = 74.6 [C(3-Phpz)2(phOH)], 102.9
155.1 [2-C (py)] ppm. IR (KBr): ν = 3149 (vw, ν
), 3089 (vw,
˜
CHarom
Eur. J. Org. Chem. 2010, 4136–4144
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4141

A. Hoffmann, U. Flörke, M. Schürmann, S. Herres-Pawlis
FULL PAPER
[4-C (3-Phpz)], 116.4 [6-C (phOH)], 119.8 [4-C (phOH)], 122.5 [2-
(qu)], 128.0 [7-C (qu)], 128.6 [6-C (qu)], 128.6 [5-C (qu)], 130.1 [9-
C (phOH)], 125.4 [o-C(3-Phpz)], 127.7 [p-C(3-Phpz)], 128.5 [m-C(3- C (qu)], 130.7 [8-C (qu)], 131.1 [5-C (3-tBupz)], 137.8 [4-C (qu)],
Phpz)], 128.9 [3-C (phOH)], 130.9 [5-C (phOH)], 131.3 [5-C (3- 148.1 [10-C (qu)], 156.9 [2-C (qu)], 163.3 [Cpz (3-tBupz)] ppm. IR
Phpz)], 133.3 [Cph (3-Phpz)], 151.9 [Cpz (3-Phpz)], 154.8 [1-C (KBr) ν = 3136 (vw, ν
), 3112 (vw, νCH ), 3062 (vw, νCH ),
˜
CHarom
(phOH)] ppm. IR (KBr): ν = 3131 (vw, ν
), 3106 (vw, νCH ),
3043 (vw, νCH ), 3004 (vw, νCH ), 2962ar(omm , νCH ), 2925 a(rvomw,
˜
CHarom
arom
aliph
3064 (vw, νCH ), 3029 (vw, νCH ), 2960 (vw, νCH ), 2924 a(rvomw,
νCH ), 2900 (vw, νCH ), 2859 (avrowm, νCH ), 2751 (vw), 1716 (w),
arom
arom
aliph
aliph
aliph
aliph
νCH ), 2877 (vw, νCH ), 2832 (vw, νCH ), 2732 (vw), 2605 (vw),
1617 (w), 1596 (m), 1560 (vw), 1521 (s), 1506 (m), 1481 (w), 1459
(m), 1428 (vw), 1400 (vw), 1361 (s), 1321 (vw), 1307 (vw), 1247
aliph
aliph
2474 (vw), 1961 (vw), a1lip8h86 (vw), 1810 (vw), 1758 (vw), 1704 (vw),
1644 (vw), 1606 (w), 1554 (vw), 1529 (w), 1496 (s), 1463 (s), 1409 (vs), 1220 (w), 1157 (w), 1118 (vw), 1052 (s), 1025 (vw), 1014 (w),
(vw), 1398 (w), 1384 (w), 1359 (vw), 1326 (m), 1307 (vw), 1295 (m),
1280 (vw), 1261 (m), 1238 (m), 1213 (m), 1176 (vw), 1160 (vw),
1124 (w), 1097 (m), 1083 (s), 1074 (s), 1056 (s), 1049 (s), 997 (w),
950 (w), 912 (vw), 873 (m), 852 (vw), 813 (w), 788 (m), 775 (m),
997 (vw), 981 (vw), 954 (vw), 906 (m), 873 (vw), 804 (vs), 781 (vs),
761 (vs), 725 (m), 698 (vw), 669 (vw), 620 (w), 599 (vw), 586 (vw),
555 (vw), 522 (vw), 478 (w), 443 (vw), 418 (vw) cm–1. MS (EI): m/z
(%) = 387.2 (15) [M+ = C24H29N5+], 279.1 (15), 265.1 (20), 264.1
759 (vs), 754 (vs), 700 (m), 692 (m), 638 (w), 620 (vw), 549 (vw), (65) [M+ – C7H11N2], 259.1 (10) [M+ – C9H6N], 255.1 (7), 250.1
530 (vw), 520 (vw), 476 (vw), 447 (vw), 418 (vw) cm–1. MS (EI):
m/z (%) = 392.2 (3) [M+ = C25H20N4O+], 250.1 (1), 249.1 (6) [M+
(9), 248.1 (4), 208.1 (14), 168.1 (7), 167.1 (13), 157.1 (5), 156.1 (4),
–
137.1 (10), 129.1 (26) [C9H7N+], 128.1 (32) [C9H6N+], 127.1 (3),
C9H7N2], 248.1 (26), 247.1 (2), 146.1 (2), 145.1 (28), 144.1 (100) 125.1 (5), 124.1 (23) [C7H12N2+], 113.1 (3), 110.1 (7), 109.1 (100),
[C9H8N2+], 143.1 (20), 142.1 (1), 118.1 (4), 117.1 (17), 116.1 (8),
102.1 (5), 101.1 (7), 82.1 (4), 81.1 (20), 77.1 (5), 75.1 (3), 71.1 (6),
115.1 (25), 114.1 (2), 93.1 (19) [C6H5O+], 92.1 (2), 91.1 (2), 90.1
70.1 (5), 69.1 (24), 68.1 (2), 63.1 (7), 57.1 (20) [C4H9+]. C24H29N5
(13), 89.1 (11), 88.1 (2), 78.1 (3), 77.1 (20), 76.1 (3). C25H20N4O (387.2): calcd. C 74.38, H 7.54, N 18.07; found C 74.17, H 7.38, N
(392.1): calcd. C 76.51, H 5.14, N 14.28; found C 76.07, H 5.06, N
14.28.
17.67.
(2-Hydroxyphenyl)bis(3-tert-pyrazolyl)methane (3-tBupz)2(phOH)-
(2-Pyridinyl)bis(3-tert-pyrazolyl)methane (3-tBupz)2(py)CH (L7): CH (L9): Following the general synthesis, 3-tert-butylpyrazole
Following the general synthesis, 3-tert-butylpyrazole (12.4 g,
100 mmol) and pyridine-2-carbaldehyde (4.8 mL, 50 mmol) were
(12.4 g, 100 mmol) and salicylaldehyde (5.3 mL, 50 mmol) were
used. The final product was obtained as an orange solid (9.6 g,
55%). M.p. 85 °C. 1H NMR (500 MHz, [D6]acetone, 25 °C): δ =
used. The final product was obtained as a red waxy solid (10.2 g,
1
60%). H NMR (500 MHz, [D6]acetone, 25 °C): δ = 1.26 [s, 18 H, 1.26 [s, 18 H, CH3 (3-tBupz)], 6.20 [d, JH,H = 2.3 Hz, 2 H, 4-H (3-
CH3 (3-tBupz)], 6.22 [d, JH,H = 2.5 Hz, 2 H, 4-H (3-tBupz)], 7.08
tBupz)], 6.89 [t, JH,H = 7.6 Hz, 1 H, 4-H (phOH)], 6.98 [dd, JH,H
[d, JH,H = 7.9 Hz, 1 H, 3-H(py)], 7.32 [t, JH,H = 6.6 Hz, 1 H, 5-H = 1.0, 8.2 Hz, 1 H, 6-H (phOH)], 7.18 [dd, JH,H = 1.4, 7.6 Hz, 1
(py)], 7.62 [d, JH,H = 2.4 Hz, 2 H, 5-H (3-tBupz)], 7.66 (s, 1 H,
CH), 7.77 [t, JH,H = 7.8 Hz, 1 H, 4-H(py)], 8.56 [d, JH,H = 4.5 Hz,
1 H, 6-H (py)] ppm. 13C NMR (125 MHz, [D6]acetone, 25 °C): δ
= 30.8 (CH3, 3-tBupz), 32.6 (C, 3-tBupz), 79.3 [C(3-tBupz)2(py)],
H, 3-H (phOH)], 7.30 [t, JH,H = 8.1 Hz, 1 H, 5-H (phOH)], 7.57
[d, JH,H = 2.4 Hz, 2 H, 5-H (3-tBupz)], 7.73 (s, 1 H, CH) ppm. 13
NMR (125 MHz, [D6]acetone, 25 °C): δ = 29.8 (C, 3-tBupz), 31.8
(CH3, 3-tBupz), 75.8 [C(3-tBupz)2(phOH)], 101.9 [4-C (3-tBupz)],
C
103.2 [4-C (3-tBupz)], 122.8 [3-C (py)], 124.4 [5-C(py)], 130.8 [5-C 117.6 [6-C (phOH)], 119.5 [4-C (phOH)], 122.8 [2-C (phOH)], 129.9
(3-tBupz)], 137.7 [4-C (py)], 150.0 [6-C (py)], 156.7 [2-C (py)], 162.9 [3-C (phOH)], 130.1 [5-C (3-tBupz)], 130.9 [5-C (phOH)], 155.4 [1-
[Cpz (3-tBupz)] ppm. IR (KBr) ν = 3132 (vw, ν ), 3056 (vw,
C (phOH)], 162.2 [Cpz (3-tBupz)] ppm. IR (KBr) ν = 3130 (vw,
˜
˜
CHarom
νCH ), 2964 (m, νCH ), 2902 (vw, νCH ), 2865 (vw, νCH ),
νCH ), 3072 (vw, νCH ), 2960 (s, νCH ), 2902 (w, νCH ), 2867
arom
aliph
aliph
aliph
arom
aliph
aliph
2821 (vw, νCH ), 1714 (vw), 1650 (vw), 1590 (w), 1574 (vw), 1521 (w, νCH ), 2773 (vw),a2ro7m15 (vw), 2597 (vw), 2466 (vw), 1716 (vw),
(m), 1463 (w),al1iph436 (w), 1404 (vw), 1385 (vw), 1361 (m), 1328 (w),
1309 (vw), 1247 (s), 1207 (w), 1187 (vw), 1159 (w), 1095 (vw), 1054
1606 (s), 1583 (w), 1558 (vw), 1521 (s), 1482 (m), 1459 (vs), 1421
(vw), 1401 (vw), 1361 (s), 1339 (w), 1322 (w), 1297 (m), 1251 (s),
aliph
(s), 1026 (vw), 1015 (vw), 993 (w), 979 (vw), 927 (vw), 895 (vw), 1245 (vs), 1207 (m), 1174 (vw), 1157 (m), 1099 (m), 1054 (vs), 1025
869 (w), 854 (vw), 844 (vw), 828 (vw), 808 (m), 786 (w), 758 (vs), (w), 1013 (w), 995 (w), 977 (vw), 933 (vw), 896 (m), 873 (m), 883
725 (w), 700 (vw), 669 (w), 652 (vw), 624 (vw), 612 (vw), 592 (vw), (vw), 811 (m), 794 (m), 754 (vs), 723 (s), 669 (vw), 647 (w), 637
501 (vw), 489 (vw), 443 (vw), 401 (w) cm–1. MS (EI): m/z (%) =
(vw), 615 (vw), 609 (vw), 590 (vw), 545 (w), 497 (vw), 478 (vw),
337.3 (33) [M+ = C20H27N5+], 259.3 (25) [M+ – C5H4N], 215.2 (22), 441 (vw) cm–1. MS (EI): m/z (%) = 352.2 (80) [M+ = C21H28N4O+],
214.2 (100) [M+ – C7H11N2], 200.2 (8), 199.2 (2), 198.2 (3), 158.1 259.2 (7) [M+ – C6H5O], 230.2 (22), 229.2 (91) [M+ – C7H11N2],
(7), 124.1 (16) [C7H12N2+], 118.1 (7), 109.1 (75), 106.1 (5), 93.1 (2),
214.2 (22), 213.3 (88), 199.2 (4), 186.1 (32), 173.1 (12), 172.1 (28)
92.1 (5), 81.1 (12), 78.1 (12) [C5H4N+], 69.1 (12), 57.1 (11) [C4H9+]. [C10H8N2O+], 171.1 (91), 146.1 (52), 145.1 (98) [C7H5N4+], 144.1
C20H27N5 (337.3): calcd. C 71.18, H 8.06, N 20.75; found C 71.08, (11), 133.1 (5), 132.1 (12), 124.1 (24), 123.1 (2) [C7H11N2+], 121.1
H 8.01, N 20.71.
(4), 120.1 (14), 110.1 (10), 109.1 (89), 95.1 (12), 94.1 (5), 93.1 (7)
[C6H5O+], 92.1 (10), 91.1 (9), 81.1 (25), 80.1 (5), 79.1 (9), 78.1 (5),
77.1 (19), 69.1 (25), 57.1 (53) [C4H9+]. C21H28N4O (352.1): calcd.
C 71.56, H 8.01, N 15.90; found C 70.47, H 7.88, N 15.57.
(2-Quinolinyl)bis(3-tert-pyrazolyl)methane (3-tBupz)2(qu)CH (L8):
Following the general synthesis, 3-tert-butylpyrazole (12.4 g,
100 mmol) and quinoline-2-carbaldehyde (7.9 g, 50 mmol) were
used. The final product was obtained as a dark-red waxy solid
(2-Pyridinyl)bis(3-mesitylpyrazolyl)methane
(3-Mspz)2(py)CH
1
(11.2 g, 59%). H NMR (500 MHz, [D6]acetone, 25 °C): δ = 1.26
(L10): Following the general synthesis, 3-mesitylpyrazole (18.6 g,
[s, 18 H, CH3 (3-tBupz)], 6.25 [d, JH,H = 2.5 Hz, 2 H, 4-H (3- 100 mmol) and pyridine-2-carbaldehyde (4.8 mL, 50 mmol) were
tBupz)], 7.30 [d, JH,H = 8.6 Hz, 1 H, 3-C (qu)], 7.58 [t, JH,H
=
used. The final product was obtained as a yellow solid (16.8 g,
73%). M.p. 128 °C. H NMR (500 MHz, CDCl3, 25 °C): δ = 2.05
[s, 12 H, CH3, (3-Mspz)], 2.33 [s, 6 H, CH3, (3-Mspz)], 6.18 [d,
JH,H = 1.6 Hz, 2 H, 4-H (3-Mspz)], 6.90 [s, 4 H, m-H (3-Mspz)],
1
7.6 Hz, 1 H, 7-H (qu)], 7.71 [d, JH,H = 2.4 Hz, 2 H, 5-H (3-tBupz)],
7.73 [t, JH,H = 6.6 Hz, 1 H, 8-H (qu)], 7.84 (s, 1 H, CH), 7.91 [d,
JH,H = 8.1 Hz, 1 H, 6-H (qu)], 7.99 [d, JH,H = 8.4 Hz, 1 H, 9-H
(qu)], 8.31 [d, JH,H = 8.6 Hz, 1 H, 4-H (qu)] ppm. 13C NMR 7.13 [m, 1 H, 3-H (py)], 7.24 [m, 1 H, 5-H (py)], 7.32 (s, 1 H, CH),
(125 MHz, [D6]acetone, 25 °C): δ = 30.8 (CH3, 3-tBupz), 32.7 (C,
3-tBupz), 79.8 [C(3-tBupz)2(qu)], 103.7 [4-C (3-tBupz)], 120.6 [3-C
7.52 [d, JH,H = 1.7 Hz, 2 H, 3-H (3-Mspz)], 7.55 [m, 1 H, 4-H (py)],
8.27 [d, JH,H = 4.4 Hz, 1 H, 6-H (py)] ppm. 13C NMR (125 MHz,
4142
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 4136–4144

Efficient Synthesis of Substituted Bis(pyrazolyl)(2-pyridyl)methane Ligands
CDCl3, 25 °C): δ = 20.6 [C (3-Mspz)], 21.4 [CCH ,p (3-Mspz)], (2-Hydroxyphenyl)bis(3-mesitylpyrazolyl)methane (3-Mspz)2(phOH)-
CH3,o
3
75.2 [C(3-Mspz)2(phOH)], 106.1 [4-C (3-Mspz)], 123.7 [3-C (py)], CH (L12): Following the general synthesis, 3-mesitylpyrazole
125.4 [5-C (py)], 128.5 [m-C (3-Mspz)], 128.6 [CMs (3-Mspz)], 136.0 (18.6 g, 100 mmol) and salicylaldehyde (5.3 mL, 50 mmol) were
[5-C (3-Mspz)], 136.3 [4-C (py)], 138.4 [o-C (3-Mspz)], 140.2 [p-C
(3-Mspz)], 144.6 [Cpz (3-Mspz)], 148.4 [6-C (py)], 156.4 [6-C (py)] M.p. 135 °C. H NMR (500 MHz, CDCl3, 25 °C): δ = 2.07 [s, 12
ppm. IR (KBr) ν = 3163 (m, ν ), 3123 (w, νCH ), 3071 (vw, H, CH3, (3-Mspz)], 2.33 [s, 6 H, CH3, (3-Mspz)], 6.20 [d, JH,H
used. The final product was obtained as a white solid (18.1 g, 76%).
1
=
˜
CHarom
arom
νCH ), 3034 (vw, νCH ), 2949 (w, νCH ), 2919 (w, νCH ), 2854
2.3 Hz, 2 H, 4-H (3-Mspz)], 6.89 [d, JH,H = 7.9 Hz, 1 H, 6-H
(phOH)], 6.92 [s, 4 H, m-H (3-Mspz)], 6.96 [d, JH,H = 7.5 Hz, 1 H,
4-H (phOH)], 7.28 [t, JH,H = 7.8 Hz, 1 H, 5-H (phOH)], 7.34 [d,
arom
arom
aliph
(vw, νCH ), 2825 (vw, νCH ), 2794 (vw), 2737 (vw), 2a5li9ph7 (vw),
aliph
aliph
2708 (vw), 1735 (vw), 1717 (vw), 1702 (vw), 1686 (vw), 1654 (vw),
1637 (vw), 1613 (m), 1590 (w), 1573 (w), 1544 (m), 1509 (vw), 1455 JH,H = 7.4 Hz, 1 H, 3-H (phOH)], 7.68 (s, 1 H, CH), 7.82 [d, JH,H
(s), 1438 (m), 1384 (m), 1356 (vw), 1335 (m), 1315 (m), 1288 (w),
1231 (w), 1199 (vs), 1168 (vw), 1151 (vw), 1100 (w), 1077 (w), 1046
= 2.4 Hz, 2 H, 5-H (3-Mspz)], 9.91 (br., 1 H, OH) ppm. 13C NMR
(125 MHz, CDCl3, 25 °C): δ = 20.4 [C
(3-Mspz)], 21.1 [CCH ,p
CH3,o
(m), 1030 (w), 1015 (w), 996 (vw), 980 (vw), 964 (vw), 938 (w), 921 (3-Mspz)], 78.1 [C(3-Mspz)2(phOH)], 107.2 [4-C (3-Mspz)], 1193.9
(w), 874 (m), 852 (vs), 826 (m), 813 (m), 795 (m), 768 (vs), 743 (m),
[6-C (phOH)], 121.1 [2-C (phOH)], 128.0 [4-C (phOH)], 128.1 [m-
732 (m), 707 (vw), 673 (vw), 663 (vw), 649 (vw), 615 (w), 600 (vw), C (3-Mspz)], 130.0 [CMs (3-Mspz)], 130.9 [3-C (phOH)], 131.0 [5-
578 (w), 500 (vw), 470 (w), 447 (vw), 407 (vw) cm–1. MS (ESI): m/z
C (3-Mspz)], 131.8 [5-C (phOH)], 137.4 [o-C (3-Mspz)], 137.8 [p-C
(3-Mspz)], 152.0 [Cpz (3-Mspz)], 155.7 [1-C (phOH)] ppm. IR
(%) = 462.3 (22) [M+ = C30H31N5++ H], 277.2 (18), 276.2 (100)
+
[C18H18N3+], 187.2 (15) [C12H13N2 + 2H]. C30H31N5 (461.6): (KBr): ν = 3154 (w, ν
), 3119 (vw, νCH ), 3032 (vw, νCH ),
˜
CHarom
arom
calcd. C 78.06, H 6.77, N 15.17; found C 77.92, H 6.63, N 15.05.
3012 (vw, νCH ), 2949 (w, νCH ), 2919ar(owm, νCH ), 2855 (vw,
arom
aliph
νCH ), 2825 (vw, νCH ), 2728al(ipwh ), 2597 (vw), 2468 (vw), 2381
aliph
aliph
(2-Quinolinyl)bis(3-mesitylpyrazolyl)methane (3-Mspz)2(qu)CH
(vw), 2346 (vw), 2304 (vw), 2281 (vw), 2100 (vw), 1959 (vw), 1923
(vw), 1883 (vw), 1802 (vw), 1762 (vw), 1734 (vw), 1717 (vw), 1702
(vw), 1685 (vw), 1654 (vw), 1612 (vs), 1602 (vs), 1575 (w), 1542
(w), 1526 (m), 1503 (m), 1488 (s), 1459 (vs), 1375 (m), 1330 (w),
1315 (s), 1289 (vw), 1266 (m), 1234 (s), 1203 (s), 1168 (w), 1155
(w), 1101 (s), 1085 (m), 1049 (vs), 1029 (s), 996 (w), 983 (vw), 964
(w), 932 (m), 875 (s), 851 (vs), 815 (m), 799 (m), 790 (m), 762 (vs),
743 (s), 721 (m), 655 (vw), 640 (m), 626 (vw), 615 (vw), 601 (vw),
577 (w), 547 (w), 535 (vw), 502 (vw), 470 (w), 452 (vw), 437 (vw),
421 (vw) cm–1. MS (EI): m/z (%) = 476.2 (11) [M+ = C31H32N4O+],
387.2 (5), 290. 1 (6) [M+ – C12H14N2], 264.1 (23), 208.1 (4), 197.1
(84), 187.1 (34), 186.1 (100), 185.1 (45) [C12H13N2+], 171.1 (37)
[C10H7N2O+], 170.1 (13), 169.1 (12), 168.1 (12), 159.1 (50), 158.1
(84), 157.1 (13), 156.1 (9), 155.1 (7), 154.1 (8), 145.1 (10)
[C7H5N4+], 144.1 (76), 143.1 (25), 142.1 (20), 141.1 (21), 131.1 (6),
130.1 (8), 129.1 (13), 128.1 (20), 127.1 (8), 122.1 (30), 121.1 (29),
115.1 (29), 104.1 (5), 103.1 (6), 93.1 (14) [C6H5O+], 91.1 (16), 77.1
(14), 76.1 (8), 66.1 (4) [C3H2N2+], 65.1 (15). C31H32N4O (476.2):
calcd. C 78.12, H 6.77, N 11.76; found C 77.87, H 6.71, N 11.92.
(L11): Following the general synthesis, 3-mesitylpyrazole (18.6 g,
100 mmol) and quinoline-2-carbaldehyde (7.9 g, 50 mmol) were
used. The final product was obtained as an orange solid (17.8 g,
1
70%). M.p. 122 °C. H NMR (500 MHz, CDCl3, 25 °C): δ = 2.13
[s, 12 H, CH3, (3-Mspz)], 2.30 [s, 6 H, CH3, (3-Mspz)], 6.31 [d,
JH,H = 2.5 Hz, 2 H, 4-H (3-Mspz)], 6.90 [s, 4 H, m-H (3-Mspz)],
7.18 [d, JH,H = 8.5 Hz, 1 H, 3-H (qu)], 7.45 (s, 1 H, CH), 7.51 [t,
JH,H = 7.5 Hz, 1 H, 7-H (qu)], 7.65 [t, JH,H = 7.4 Hz, 1 H, 8-H
(qu)], 7.78 [m, 1 H, 6-H (qu)], 7.96 [m, 1 H, 9-H (qu)], 7.97 [d,
JH,H = 2.5 Hz, 2 H, 5-H (3-Mspz)], 8.14 [d, JH,H = 8.5 Hz, 1 H, 4-
H (qu)] ppm. 13C NMR (125 MHz, CDCl3, 25 °C): δ = 20.4 [C
CH3,o
(3-Mspz)], 21.1 [CCH ,p (3-Mspz)], 75.9 [C(3-Mspz)2(phOH)], 107.7
3
[4-C (3-Mspz)], 118.6 [3-C(qu)], 126.9 [7-C (qu)], 127.5 [6-C (qu)],
127.6 [5-C (qu)], 128.0 [m-C (3-Mspz)], 129.5 [5-C (3-Mspz)], 129.6
[8-C(qu)], 129.7 [9-C(qu)], 130.7 [CMs (3-Mspz)], 136.9 [4-C(qu)],
137.6 [o-C (3-Mspz)], 138.7 [p-C (3-Mspz)], 147.5 [10-C(qu)], 151.0
[Cpz (3-Mspz)], 156.3 [2-C (qu)] ppm. IR (KBr) ν = 3162 (w,
˜
νCH ), 3119 (vw, νCH ), 3064 (vw, νCH ), 3032 (vw, νCH ),
arom
2950 (w, νCH ), 2918 a(rowm, νCH ), 2854 (avrowm, νCH ), 2731 (avrowm),
aliph
aliph
aliph
1735 (vw), 1718 (vw), 1700 (vw), 1685 (vw), 1613 (s), 1595 (m), (2-Pyridinyl)(phenyl)[bis(3-phenylpyrazolyl)]methane (3-Phpz)2(py)-
1576 (w), 1560 (w), 1544 (w), 1528 (vw), 1505 (m), 1488 (m), 1452 (ph)C (L13): NaH (2.4 g, 100 mmol) was suspended in freshly dis-
(m), 1429 (m), 1384 (m), 1333 (m), 1304 (m), 1263 (vw), 1234 (m),
tilled THF (100 mL) and stirred at 0 °C. 3-Phenylpyrazole (14.4 g,
1223 (w), 1199 (m), 1167 (vw), 1151 (vw), 1140 (vw), 1115 (vw), 100 mmol) was added gradually to the suspension over 15 min and
1100 (vw), 1079 (w), 1043 (m), 1013 (w), 982 (vw), 964 (vw), 925 the stirring was continued at 0 °C until gas evolution stopped (ca.
(vw), 907 (w), 876 (vw), 852 (s), 811 (vs), 797 (s), 776 (vs), 744 (m),
708 (vw), 660 (vw), 632 (vw), 618 (w), 578 (vw), 557 (vw), 523 (vw),
512 (vw), 501 (vw), 478 (vw), 446 (vw), 421 (vw) cm–1. MS (EI):
m/z (%) = 511.3 (11) [M+ = C34H33N5+], 444.1 (10), 328.2 (5), 327.2
(29), 326.2 (19) [M+ – C12H13N2], 325.2 (5), 314.1 (7), 241.1 (9),
240.1 (65), 239.1 (21), 199.2 (12), 198.2 (10) [C13H14N2+], 197.1
(46), 196.2 (8), 187.2 (17), 186.1 (100), 185.1 (43) [C12H13N2+],
184.1 (10), 183.1 (20), 182.1 (9), 181.1 (16), 171.1 (19), 170.1 (14)
30 min.). Then, thionyl chloride (3.7 mL, 50 mmol) was added
dropwise to this pale-brown solution at 0 °C. After stirring for an
additional 45 min at 0 °C and then 30 min at room temperature,
benzoyl pyridine (4.6 g, 25 mmol) and a catalytic amount of co-
balt(II) chloride were added, and the reaction mixture was heated
under vigorous stirring at reflux overnight. During this time period
the mixture turned intensely blue pink and evolution of SO2 was
observed. The reaction mixture was allowed to cool to room tem-
[C11H10N2+], 169.1 (30), 168.1 (18), 167.1 (10), 159.1 (36), 258.1 perature before diethyl ether (50 mL) and water (100 mL) were
(74), 157.1 (19), 156.1 (26), 155.1 (25) [C10H7N2+], 154.1 (16), 153.1
gradually added. The biphasic solution was then stirred for 1 hour.
(9), 145.1 (13) [C7H5N4+], 144.1 (60), 143.1 (81), 142.1 (37), 141.1 The layers were separated, and the aqueous phase was extracted
(29) [C10H7N+], 140.1 (10), 131.1 (19), 130.1 (19), 129.1 (52), 128.1 with diethyl ether (3ϫ60 mL). The combined organic phase was
(78) [C9H6N+], 127.1 (14), 119.0 (36) [C9H11+], 117.1 (12), 116.1
(18), 115.1 (45), 113.1 (11), 111.2 (14), 109.2 (10), 103.1 (10), 102.1
(10), 101.1 (14), 99.2 (13), 98.1 (33), 97.1 (21), 95.1 (15), 91.1 (35),
85.2 (28), 84.1 (10), 83.1 (20), 81.1 (17), 79.1 (11) [C4H3N+], 77.1
washed with distilled water, dried with sodium sulfate and filtered.
The solvent was then removed in vacuo, and the residual substi-
tuted pyrazole was removed by distillation under vacuum (135 °C,
0.9 Torr). The crude product was suspended in hexane, and the
(19), 71.1 (41), 70.1 (17), 69.1 (30), 67.0 (14) [C3H3N2+]. C34H33N5 flask was placed in an ultrasound bath to break up the lumps that
(511.3): calcd. C 79.71, H 6.50, N 13.69; found C 79.47, H 6.75, N
13.51.
had formed, yielding a solid. This solid was collected by filtration
and dried in vacuo. A brown solid (8.7 g, 77%) resulted as the final
Eur. J. Org. Chem. 2010, 4136–4144
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4143

A. Hoffmann, U. Flörke, M. Schürmann, S. Herres-Pawlis
FULL PAPER
product. M.p. 122 °C. H NMR (500 MHz, [D6]acetone, 25 °C): δ
1
[11] T. C. Higgs, C. J. Carrano, Eur. J. Org. Chem. 2002, 3632–3645.
[12] D. L. Reger, J. R. Gardinier, T. C. Grattan, M. D. Smith, J. Or-
ganomet. Chem. 2005, 690, 1901–1912.
[13] Z. Shirin, C. J. Carrano, Polyhedron 2004, 23, 239–244.
[14] T. C. Higgs, C. J. Carrano, Inorg. Chem. 1997, 36, 291–297.
[15] A. D. Schofield, M. L. Barros, M. G. Cushion, A. D. Schwarz,
P. Mountford, Dalton Trans. 2009, 85–96.
[16] S. Scheuermann, T. Kretz, H. Vitze, J. W. Bats, M. Bolte, H.-
W. Lerner, M. Wagner, Chem. Eur. J. 2008, 14, 2590–2601.
[17] D. L. Reger, R. P. Watson, M. D. Smith, P. J. Pellechia, Organo-
metallics 2006, 25, 743–755.
[18] L1 and L3 have already been reported. Ligand L1 was first
synthesized by Canty[10] and L2 by Carrano,[11] but here the
yield is considerably higher and the synthesis proceeds without
the use of phosgene.
[19] D. L. Reger, T. C. Grattan, K. J. Brown, C. A. Little, J. J. S.
Lamba, A. L. Rheingold, R. D. Sommer, J. Organomet. Chem.
2000, 607, 120–128.
[20] The listed chemical shifts are measured in CDCl3 for all li-
gands. For a more detailed assignment of all shifts the solvent
is changed in the experimental section because in CDCl3 a de-
tailed assignment is not easily possible.
[21] M. C. López Gallego-Preciado, P. Ballesteros, R. M.
Claramunt, M. Cano, J. V. Heras, E. Pinilla, A. Monge, J. Or-
ganomet. Chem. 1993, 450, 237–244.
[22] A. Neuba, E. Akin, S. Herres-Pawlis, U. Flörke, G. Henkel,
Acta Crystallogr., Sect. C 2008, 64, m194–m197.
= 6.79 [d, JH,H = 2.5 Hz, 2 H, 4-H (3-Phpz)], 7.27 [t, JH,H = 7.3 Hz,
2 H, p-H (3-Phpz)], 7.33–7.35 [m, 6 H, m-H (3-Phpz) and o-H (ph)],
7.37 [m, 1 H, o-H (ph)], 7.41 [m, 2 H, m-H (ph)], 7.42 [m, 1 H, 3-
H (py)], 7.43 [m, 1 H, 5-H (py)], 7.60 [d, JH,H = 2.6 Hz, 2 H, 5-H
(3-Phpz)], 7.77 [d, JH,H = 8.0 Hz, 2 H, o-H (3-Phpz)], 7.87 [t, JH,H
= 7.8 Hz, 1 H, 4-H (py)], 8.62 [dd, JH,H = 1.9, 4.7 Hz, 1 H, 6-H
(py)] ppm. 13C NMR (125 MHz, [D6]acetone, 25 °C): δ = 87.7 [C(3-
Phpz)2(py)(ph)], 102.6 [4-C (3-Phpz)], 123.6 [3-C (py)], 124.6 [5-C
(py)], 125.6 [o-C(3-Phpz)], 127.5 [p-C(3-Phpz)], 127.7 [m-C(ph)],
128.4 [m-C(3-Phpz)], 128.7 [o-C(ph)], 129.5 [p-C(ph)], 133.4 [Cph
(3-Phpz)], 134.0 [5-C (3-Phpz)], 136.6 [4-C (py)], 140.0 [C(ph)],
148.2 [6-C (py)], 151.6 [Cpz (3-Phpz)], 158.5 [2-C (py)] ppm. IR
(KBr): ν = 3149 (vw, ν
), 3099 (vw, νCH ), 3058 (vw, νCH ),
˜
CHarom
3031 (vw, νCH ), 2923 (vw, νCH ), 1953ar(ovmw), 1889 (vw), 1810
arom
arom
(vw), 1772 (vw), 1754 (vw), 1700 a(livphw), 1652 (vw), 1585 (w), 1560
(vw), 1529 (w), 1498 (m), 1455 (m), 1432 (w), 1382 (vw), 1355 (w),
1323 (vw), 1301 (vw), 1270 (vw), 1205 (m), 1154 (vw), 1099 (w),
1074 (m), 1049 (m), 1026 (vw), 1011 (vw), 993 (vw), 948 (vw), 937
(vw), 916 (vw), 898 (vw), 869 (w), 750 (vs), 694 (vs), 657 (vw), 619
(vw), 505 (vw), 468 (vw), 444 (vw), 428 (vw), 416 (vw), 408 (vw)
cm–1. MS (EI): m/z (%) = 453.1 (82) [M+ = C30H23N5+], 376.1 (7)
[M+ – C6H5], 375.1 (11) [M+ – C5H4N], 334.1 (6), 333.1 (7), 312.1
(33), 311.1 (95) [M+ – C12H10], 310.1 (100) [M+ – C9H7N2], 309.1
(58), 308.1 (21), 285.1 (7), 284.1 (14), 283.1 (7), 282.1 (8), 281.1
[23] B. Marten, K. Kim, C. Cortis, R. A. Friesner, R. B. Murphy,
M. N. Ringnalda, D. Sitkoff, B. Honig, J. Am. Chem. Soc.
1996, 100, 11775–11788.
[24] S. Trofimenko, J. C. Calabrese, J. S. Thompson, Inorg. Chem.
1987, 26, 1507–1514.
[25] A. L. Rheingold, C. B. White, S. Trofimenko, Inorg. Chem.
1993, 32, 3471–3477.
[26] G. M. Sheldrick, Acta Crystallogr., Sect. A 1990, 46, 467–473.
[27] G. M. Sheldrick, SHELXL, University of Göttingen,
Göttingen, Germany, 1997.
(10), 234.1 (11), 233.1 (17) [M+ – C15H12N2], 232.2 (11) [M+
–
C14H11N3], 231.1 (6), 207.1 (15), 206.1 (17), 205.1 (34), 204.1 (6),
181.1 (15), 180.1 (19), 179.1 (9), 169.1 (7), 168.1 (72), 167.1 (91)
[M+ – C18H14N4], 166.1 (19), 155.1 (9) [C10H7N2+], 144.1 (57)
[C7H4N4+], 128.1 (15), 117.1 (8), 116.1 (6), 115.1 (31), 105.1 (5),
104.1 (13), 103.1 (20), 102.1 (6), 89.1 (11), 78.1 (20) [C5H4N+], 77.1
(48) [C6H5+]. C30H23N5 (453.1): calcd. C 79.45, H 5.11, N 15.44;
found C 79.27, H 4.96, N 15.28.
[28] G. M. Sheldrick, International Tables for X-ray Crystallogra-
phy, Kluwer Academic, Dordrecht, The Netherlands, 1997.
[29] G. M. Sheldrick, SHELXTL, Release 5.1, Software Reference
Manual, Bruker AXS, Madison, WI, 1997.
[30] Bruker, SMART (v. 5.62), SAINT (v. 6.02), SHELXTL (v.
6.10), and SADABS (v. 2.03), Bruker AXS Inc., Madison, Wis-
consin, U.S.A., 2002.
Acknowledgments
S. H.-P. thanks the Fonds der Chemischen Industrie for granting a
Liebig fellowship. Furthermore, S. H.-P. thanks Prof. Dr. K. Jurk-
schat and the Technische Universität Dortmund for valuable sup-
port.
[31] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, J. A. Montgomery Jr., T.
Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N.
Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K.
Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y.
Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P.
Hratchian, J. B. Cross, C. Adamo, J. Jaramillo, R. Gomperts,
R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pom-
elli, J. W. Ochterski, P. Y. Ayala, K. Morokuma, G. A. Voth, P.
Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dapprich,
A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick, A. D.
Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui,
A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu,
A. Liashenko, P. Piskorz, I. Komaromi, R. L. Martin, D. J.
Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara,
M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W.
Wong, C. Gonzalez, J. A. Pople, Gaussian 03, Revision E.01,
Gaussian, Inc., Wallingford, CT, 2004.
[1] C. Pettinari, R. Pettinari, Coord. Chem. Rev. 2005, 249, 663–
691.
[2] A. Otero, J. Fernández-Baeza, A. Antiñolo, J. Tejeda, A. Lara-
Sánchez, Dalton Trans. 2004, 1499–1510.
[3] C. Pettinari, R. Pettinari, Coord. Chem. Rev. 2005, 249, 525–
543.
[4] H. R. Bigmore, S. C. Lawrence, P. Mountford, C. S. Tredget,
Dalton Trans. 2005, 635–651.
[5] S. Trofimenko, J. Am. Chem. Soc. 1970, 92, 5118–5126.
[6] A. Otero, J. Fernández-Baeza, A. Antiñolo, J. Tejeda, A. Lara-
Sánchez, L. F. Sánchez Barba, M. Sánchez-Molina, S. Franco,
M. I. López-Solera, A. M. Rodriguez, Inorg. Chem. 2007, 46,
8475–8477.
[7] I. Hegelmann, A. Beck, C. Eichhorn, B. Weibert, N. Burzlaff,
Eur. J. Inorg. Chem. 2003, 339–347.
[8] T. Godau, F. Platzmann, F. W. Heinemann, N. Burzlaff, Dalton
Trans. 2009, 254–255.
[9] E. Galardon, M. Giorgi, I. Artaud, Dalton Trans. 2007, 1047–
1052.
[32] a) A. D. Becke, J. Chem. Phys. 1993, 98, 5648; b) C. Lee, W.
Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785; c) B. Miehlich,
A. Savin, H. Stoll, H. Preuss, Chem. Phys. Lett. 1989, 157, 200.
Received: February 12, 2010
[10] P. K. Byers, A. J. Canty, R. T. Honeyman, J. Organomet. Chem.
1990, 385, 417–427.
Published Online: June 8, 2010
4144
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 4136–4144