Synthesis, structures, and spectroscopic properties of 3-aryl-5-(2-pyridyl) pyrazoles and related pyrazoles

Article abstract of DOI:10.1002/zaac.201300637

3-Aryl-5-(2-pyridyl)pyrazoles and related compounds are easily accessible via the reaction of the appropriate 1,3-diketone with hydrazine hydrate. The central pyrazole rings show a far-reaching equalization of the bond lengths. In the crystalline state dimeric and strand-like structures are observed due to the formation of intermolecular N-H...N hydrogen bridges between the pyrazole N-H functionality and a pyrazole or pyridyl base. The structures mainly depend on the steric demand of the aryl groups. Planar 3-aryl-5-(2-pyridyl)pyrazoles also show π stacking reducing the solubility in common organic solvents. Copyright

Full text of DOI:10.1002/zaac.201300637

Job/Unit: Z13637
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Date: 06-02-14 11:07:16
Pages: 11
ARTICLE
DOI: 10.1002/zaac.201300637
Synthesis, Structures, and Spectroscopic Properties of 3-Aryl-5-(2-pyridyl)-
pyrazoles and Related Pyrazoles
Björn Schowtka,[a] Christoph Müller,[a] Helmar Görls,[a] and Matthias Westerhausen*[a]
Keywords: Pyrazole; Pyridylpyrazole; Nitrogen heterocycles; Structure elucidation; Hydrogen bonds
Abstract. 3-Aryl-5-(2-pyridyl)pyrazoles and related compounds are lecular N–H···N hydrogen bridges between the pyrazole N–H function-
easily accessible via the reaction of the appropriate 1,3-diketone with
hydrazine hydrate. The central pyrazole rings show a far-reaching
equalization of the bond lengths. In the crystalline state dimeric and
strand-like structures are observed due to the formation of intermo-
ality and a pyrazole or pyridyl base. The structures mainly depend on
the steric demand of the aryl groups. Planar 3-aryl-5-(2-pyridyl)-
pyrazoles also show π stacking reducing the solubility in common or-
ganic solvents.
groups[11,12] in 3-position and aromatic aza bases such as 2-
pyridyl,[5,9] 2-(6-methyl)pyridyl[10] and pyrazinyl substitu-
ents[13] in 5-position. These derivatives represent precursor
compounds for diverse metal complexes.
The majority of investigations deals with 3-phenyl-5-(2-pyr-
idyl)pyrazole and 3,5-bis(2-pyridyl)pyrazole as well as their
metal complexes. Despite the importance of these pyrazoles
and pyrazolates as ligands in coordination chemistry, only very
few structural studies exist on pyrazoles. In the solid state,
monomeric 5-(2-pyridyl)pyrazoles are unknown and dimers as
well as tetramers were observed (Scheme 1).[5,8,9] Dimeriza-
Introduction
Pyrazoles represent a widely used substance class with di-
verse applications in organic and organometallic chemistry.[1]
Thus, these compounds contain very acidic hydrogen atoms
enabling deprotonation and formation of metal complexes.[2]
The denticity of pyrazoles can be extended via preparation of
bis- and tris(2-pyrazolyl)boranates (scorpionates)[3] as well as
their isoelectronic congeners, the bis- and tris(2-pyrazolyl)-
methanes and -methanides.[4] Alternatively, a substituent in 3-
or 5-position containing Lewis basic sites enhances the dentic-
ity; thus 5-(2-pyridyl)pyrazolates act as bidentate chelate
bases, quite similar to the well-known 2,2Ј-bipyridine. Substit-
uents in 3-position strongly influence the structures of the pyr-
azoles, however, even Lewis basic thienyl groups do not par-
ticipate in the coordination chemistry of the corresponding
metal pyrazolates.[5] A second 2-pyridyl group gives a pyr-
azolate anion with two equal 2,2Ј-bipyridine-like coordination
sites occasionally leading to coordination polymers.[6] The
enormous impact of the pyrazolates on the coordination chem-
istry is also motivated by the ease of their synthesis.[7]
In order to study the influence of diverse aryl groups on
physical properties and molecular structures various com-
pounds were prepared. On the one hand, aryl groups in 3-posi-
tion with different steric influence can be chosen; on the other
hand, the aromatic aza ligand in 5-position can be altered.
Examples include pyrazoles with phenyl,[8,9] 2-pyridyl,[5,9]
2-(6-methyl)pyridyl,[10] thienyl,[5] furanyl,[5] and ferrocenyl
* Prof. Dr. M. Westerhausen
Fax: +49-3641-948132
E-Mail: m.we@uni-jena.de
Homepage: http://www.lsac1.uni-jena.de/
[a] Institute of Inorganic and Analytical Chemistry
Friedrich Schiller University Jena
Humboldtstrasse 8
07743 Jena, Germany
Scheme 1. Structure types I (top), II (middle) and III (bottom) of 3-
substituted 5-(2-pyridyl)pyrazoles with different intermolecular N–
H···N bridges (see text).
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201300637 or from the au-
thor.
Z. Anorg. Allg. Chem. 0000, ᭿,(᭿), 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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M. Westerhausen et al.
ARTICLE
tion can occur via intermolecular N–H···N bridges between
two pyrazole rings or between a pyrazole N–H functionality
and a pyridyl base depending on the substituent R. Herein we
distinguish the aggregation by assignment to the structure
types I, II, and III for monomeric, dimeric, and tetrameric ag-
gregates, respectively. The nature of the N–H···N bridge is
given by the index pz–pz and pz–py for bridges between two
pyrazole rings and between a pyrazole unit and a pyridyl base,
respectively. Structure type IIpz–pz is realized for derivatives
with phenyl groups in 3-position,[8,9] type IIpz–py is observed
for 2-thienyl, 2-pyridyl, and ferrocenyl-substituted com-
pounds.[5,9] Structure type IIIpz–pz was observed for derivatives
with adamantyl groups in 3-position,[12] whereas furanyl sub-
(1)
The pyrazoles 2 are distinguished by a letter as shown in
Table 1, which also contains selected NMR spectroscopic data.
Several pyrazoles show rather poor solubility in common or-
ganic solvents and therefore, resonances of the carbon atoms
C3 and C5 (which don’t carry hydrogen atoms) were not de-
tectable. The N-bound hydrogen atoms show a low field shift
δ of approx. 13 ppm. These chemical shifts hint toward rather
acidic N–H functionalities in agreement with the observations
that these compounds can easily be metalated. The acidity al-
lows the highly ionic consideration of a pyrazolate anion with
an N-bound proton. The hydrogen atoms at the pyrazole ring
show chemical shifts in the aromatic region at about 7 ppm.
For 3-(1-pyrenyl)-5-(2-pyridyl)pyrazole (2m) two resonances
at δ = 13.94 and 13.69 ppm were observed for the N–H func-
tionalities with an intensity ratio of 1:0.66. Due to the fact that
this pyrazole derivative is only very sparingly soluble we used
[D6]DMSO as solvent. A double resonance set was also found
for the pyridyl moieties in the 13C{1H} NMR spectrum but not
for the C4 atom of the pyrazole ring. These findings can be
interpreted in the sense that in very basic solvents (such as
DMSO) the pyrazole proton can be bound either at N1 (al-
lowing formation of an intramolecular N–H···Npy hydrogen
bridge) or at N2 (only enabling N–H···ODMSO hydrogen brid-
ges to the solvent).
stituents lead to type IIIpz–py/pz.
[5] (Note that in the latter struc-
ture, half of the hydrogen bridges are formed between pyrazole
rings and the other half between a pyrazole unit and a pyridyl
base.)
Results and Discussion
The β-diketone precursor compounds 1 are easily available
via Claisen condensation of appropriate esters and ketones (see
Supporting Information). The reaction of these diketones with
hydrazine hydrate in ethanol yielded the corresponding pyr-
azoles 2 with aryl groups in 3-position and aza bases (such
as pyridyl, pyrazenyl, quinolyl) in 5-position [Equation (1),
denomination of R1 and R2 and of the compounds see
Table 1]. Recrystallization from hot toluene gave the pure
products 2a to 2r.
Table 1. Selected NMR spectroscopic data of 3-aryl-5-(2-pyridyl)pyrazole and related compounds (anth anthracenyl, Fc ferrocenyl, flu fluorenyl,
iPr isopropyl, isoquin isoquinolyl, Me methyl, naph naphthyl, Ph phenyl, py pyridyl, pyr pyrenyl, pyraz pyrazenyl, quin quinolyl). The numbering
scheme is as follows:
2
3-Aryl
5-R2
ν(N–H)
δ(1HNH
)
δ(1HH4
)
δ(13CC3
)
δ(13CC4
)
δ(13CC5
)
Ref.
[8]
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
Ph
2-py
2-py
2-py
2-py
2-py
2-py
2-py
2-py
2-py
2-py
2-py
2-py
3244
3200
3136
3142
3235
3185
3234
3145
3188
3236
3118
3200
3213
3201
3257
3214
3283
12.7
7.17
7.03
6.96
6.78
6.79
6.76
6.90
7.24
7.11
7.55
7.3
7.34
7.30
7.41
7.51
7.44
7.35
7.35
143.8
151.3
100.5
100.3
100.4
104.7
104.6
104.9
100.1
104.4
106.9
101.9
100.9
101.8
105.0
102.0
102.0
104.6
101
149.7
144.9
C6H4-4-Me
C6H2-3,4,5-Me3
C6H2-2,4,6-Me3
C6H-2,3,5,6-Me4
C6H2-2,4,6-iPr3
Fc
1-naph
9-anth
2-anth
2-flu
10.90
11.72
12.26
a)
a)
n.o.
n.o.
145.2
147.3
153.0
148.9
151.7
151.6
a)
n.o.
a)
12.94
13.13
13.78
11.44
13.83
13.56
n.o.
142.5
[12]
[5]
a)
a)
n.o.
n.o.
n.o.
n.o.
n.o.
n.o.
n.o.
n.o.
a)
a)
a)
a)
a)
a)
a)
2-py
1-pyr
Ph
Ph
n.o.
148.1
148.1
b)
a)
a)
2-py
13.94
n.o.
n.o.
n.o.
a)
5-pyraz
2-quin
1-isoquin
2-py
147.2
146.7
a)
13.77
13.72
10.4
11
n.o.
n.o.
n.o.a)
a)
a)
Ph
n.o.
2-C5H3N-6-Me
2-C5H3N-6-Me
149
147
149
147
[10]
[10]
2-C5H3N-6-Me 3293
101
a) Resonance not observed (n.o.). b) A second NH resonance was observed at δ = 13.69.
2
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3-Aryl-5-(2-pyridyl)pyrazoles and Related Pyrazoles
The chemical shifts of the carbon atoms also lie in the re- bond lengths according to the valence bond formulations; how-
gion for aromatic systems. The atoms C4 lie in a very narrow ever, the differences of 2–3 pm between formal single (C–C
range between δ = 100 and 105. The δ(13C{1H}) values of C5 148, C–N 136 pm) and double bonds (C=C 134, C=N 128 pm)
(carrying the 2-pyridyl groups) lie between δ = 145 and between sp2 hybridized carbon and nitrogen atoms are small,
153 ppm and also the signals of the ring carbon atoms C3 (car- verifying a charge delocalization to a large extend. Despite the
rying the aryl substituents) appear in a narrow range at δ = fact that the molecules are planar, the distances C3–C31 and
142 to 151. This finding shows that the influence of the aryl C5–C51 between the arenes represent typical single bonds be-
substituents on the pyrazole ring is rather small and that there tween sp2 hybridized carbon atoms. One exception is deriva-
is only negligible charge delocalization from the pyrazole moi- tive 2f because the bulky isopropyl groups in ortho position
ety into the aryl rings.
enforce a nearly perpendicular arrangement of the aryl and
In order to interpret the physical data such as solubility and pyrazole rings (see Supporting Information); nevertheless, a
charge delocalization, we also investigated the molecular struc- very similar C3–C31 bond length of 148.8(2) pm was ob-
tures of these 3-aryl-5-(pyridyl)pyrazoles. Selected bond served. Methyl groups in ortho positions of the aryl groups
lengths are summarized in Table 2. The discussion of the struc- (2d and 2e) show a distortion to a lesser content.
tures can be classified in primary, secondary, and tertiary struc-
Secondary structures are built by intermolecular hydrogen
tural arrangements. The primary structure includes the intra- bridges between the pyrazole N–H functionality and pyridyl or
molecular bonding parameters. The secondary structure is con- pyrazole bases. The structure types are also included in
structed by intermolecular hydrogen bridges. The tertiary Table 2. The 3,5-bis(2-pyridyl)pyrazole (2l) crystallized with
structure is caused by π-stacking of the planar aromatic sys- two modifications 2l1 and 2l2, which are marked with the sub-
tems in the solid state.
scripts 1 (coplanar arrangement of the pyrazole units) and 2
The primary structures of the pyrazole rings show a far- (twisted arrangement of the pyrazoles). The class of 3-aryl-
reaching – but not complete – equalization of the endocyclic 5-(2-pyridyl)pyrazoles shows either hydrogen-bridged dimers
bond lengths. The pyrazole ring is numbered with the N1 atom (type II) or the formation of hydrogen-bridged strands (type
bound to C5, which carries the 2-pyridyl group. The most IV); neither monomers nor tetrameric aggregates were ob-
striking feature is the fact that the N–H functionality can be at served in the crystalline state for aryl-substituted 5-(2-pyridyl)-
N1 or at N2. This constitution influences the conformation of pyrazoles. All compounds with the N–H group at N2 form
the 2-pyridyl fragment. On the one hand, an intramolecular one-dimensional coordination polymers (2d, 2f, 2h, and 2i). In
weak N1–H···Npy bridge stabilizes the cis orientation of the these strands, only intermolecular N2–H···Npy contacts to the
pyridyl base if the hydrogen atom is bound at N1. On the other pyridyl groups are formed. A typical chain structure is depicted
hand, a N2-bound hydrogen atom leads to a trans arrangement in Figure 1 for 3-(1-naphthyl)-5-(2-pyridyl)pyrazole (2h).
of the aza base. These possibilities are depicted in Figure S6
Much more complex are the structural variations of the di-
(see Supporting Information) with 3-phenyl-5-(1-quinolyl)pyr- mers. Three different types can be recognized, namely (i) type
azole (2p) and 3-mesityl-5-(2-pyridyl)pyrazole (2d) with the IIpz–pz (2a, 2b, and 2p) with intermolecular hydrogen bridges
hydrogen atoms bound at N1 or N2, respectively. This struc- between pyrazole rings, (ii) type IIpz–py (2e, 2g, and 2l) with
tural preference leads to slight variations of the endocyclic hydrogen bridges between the N–H functionalities and pyridyl
Table 2. Selected bond lengths /pm of 3-aryl-5-(2-pyridyl)pyrazole and related compounds (anth anthracenyl, Fc ferrocenyl, iPr isopropyl, Me
methyl, naph naphthyl, Ph phenyl, py pyridyl, pyr pyrenyl, quin quinolyl). The numbering scheme is in agreement with IUPAC as shown below
und deviates from the numbering schemes of the molecule representations.
2
3-Aryl
5-R2
Struct. type
Hpz at N1/2–H N1–N2 N2–C3 C3–C4 C4–C5 N1–C5 C3–C31 C5–C51 Ref.
a
b
c
d
e
Ph
2-py
2-py
Type IIpz–pz
Type IIpz–pz
Type IIpz–py/pz N1
N1
N1
93(2)
97(3)
98(3)
98(2)
90(2)
95(3)
85(2)
94(2)
93(2)
93(2)
96(3)
95(2)
91(2)
135.1(2) 134.4(2) 140.8(2) 138.2(2) 135.3(2) 147.4(2) 146.6(2) [8]
136.4(3) 134.4(3) 141.4(3) 138.1(3) 134.7(3) 147.6(3) 147.3(3)
135.3(3) 134.2(3) 141.0(3) 138.3(3) 135.1(3) 146.7(3) 147.7(3)
135.0(2) 135.8(2) 138.5(2) 141.0(2) 134.4(2) 148.4(2) 147.2(2)
135.4(1) 133.5(2) 140.5(2) 138.0(2) 135.2(2) 148.9(2) 146.5(2)
135.1(2) 135.8(2) 137.4(2) 140.9(2) 134.2(2) 148.8(2) 146.8(2)
135.9(2) 134.2(2) 140.6(2) 137.9(2) 135.3(2) 146.4(2) 146.6(2) [12]
135.5(2) 136.2(2) 138.4(2) 141.0(2) 134.5(2) 146.8(2) 147.0(2)
135.5(2) 135.8(2) 137.6(2) 140.7(2) 134.0(2) 147.8(2) 147.1(2)
135.1(2) 134.1(2) 140.1(2) 138.3(2) 135.8(2) 147.2(2) 146.5(2) [5]
135.2(2) 134.6(3) 139.9(3) 137.2(3) 136.0(3) 146.9(3) 146.8(3) [5]
134.9(2) 134.5(2) 141.0(2) 138.8(2) 135.5(2) 147.8(2) 146.6(2)
134.7(2) 133.9(2) 141.0(2) 138.4(2) 135.2(2) 147.4(2) 147.4(2)
C6H4-4-Me
C6H2-3,4,5-Me3 2-py
C6H2-2,4,6-Me3 2-py
C6H-2,3,5,6-Me4 2-py
C6H2-2,4,6-iPr3
Fc
1-naph
9-anth
2-py
Type IVpz–py
Type IIpz–py
Type IVpz–py
Type IIpz–py
Type IVpz–py
Type IVpz–py
Type IIpz–py
Type IIpz–py
N2
N1
N2
N1
N2
N2
N1
N1
f
2-py
2-py
2-py
2-py
2-py
2-py
2-py
g
h
i
l1
l2
m
p
a)
a)
2-py
1-pyr
Ph
Type IIpz–py/pz N1
N1
1-isoquin Type IIpz–pz
a) Two modifications: 2l1 shows a coplanar, 2l2 a twisted arrangement of the pyrazole molecules within the hydrogen bridged dimer.
Z. Anorg. Allg. Chem. 0000, 0–0
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ARTICLE
Figure 1. Representation of the strand structure of 3-(1-naphthyl)-5-(2-
pyridyl)pyrazole (2h). The ellipsoids represent a probability of 40%.
Carbon-bound hydrogen atoms are neglected for clarity reasons. The
nitrogen-bound hydrogen atoms are shown with arbitrary radii.
bases, and (iii) type IIpz–py/pz (2c and 2m) with one bridge
between pyrazole units and another bridge between a N–H
moiety and a pyridyl base. In Figure 2, the representative di-
mers of each structure type (type IIpz–pz 2b; type IIpz–py 2e;
type IIpz–py/pz 2m) are depicted. Sterically unencumbered 3-
aryl-5-(2-pyridyl)pyrazoles favor type IIpz–pz in the solid state,
whereas bulkier aryl groups lead to type IIpz–py with hydrogen
bridges between pyrazole and pyridyl units. Intermediate ag-
gregation behavior with type IIpz–py/pz is observed for aryl
groups with intermediate steric influence such as 3,4,5-trimeth-
ylphenyl (2c) and pyrenyl (2m).
The tertiary structure is stabilized via π-stacking of the ar-
enes in the solid state and can be considered as a typical pack-
ing effect. In Figure 3 the packing of 3-(3,4,5-trimeth-
ylphenyl)-5-(2-pyridyl)pyrazole (2c) in the crystal is shown.
This π-stacking of the dimeric molecules reduces the solubility
in common organic solvents, thus hampering the detection of
the NMR resonances of hydrogen-free C3 and C5.
Conclusions
Pyrazoles represent a widely used substance class with the
5-(2-pyridyl)pyrazoles being a subclass with coordination
properties comparable to 2,2Ј-bipyridine. These compounds
are easily available with high yields via the reaction of β-diket-
ones with hydrazine hydrate. The N-bound hydrogen atom can
bind at either of the nitrogen bases of the pyrazole moiety. This
constitution (primary structure) influences the bond lengths of
the pyrazole ring only marginally and a charge delocalization
within the pyrazole ring is observed to a large extent. These
3-aryl-5-(2-pyridyl)pyrazoles tend to be planar, however, alkyl
groups in ortho positions of the aryl groups enforce a twisting
around the C3–C31 bonds. The C3–C31 and C5–C51 bond
lengths between the pyrazole ring and the substituents exhibit
typical values for single bonds regardless of the dihedral
angles between the arene planes. This finding suggests that the
Figure 2. Representative structures of dimers of type IIpz–pz [5-(2-pyr-
idyl)-3-(p-tolyl)pyrazole (2b), top], type IIpz–py [5-(2-pyridyl)-3-
(2,3,5,6-tetramethylphenyl)pyrazole (2e), middle], and type IIpz–py/pz
[3-(1-pyrenyl)-5-(2-pyridyl)pyrazole (2m), bottom] are depicted. The
ellipsoids represent a probability of 40%. The nitrogen-bound hydro-
gen atoms are shown with arbitrary radii, carbon-bound hydrogen
atoms are omitted.
4
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3-Aryl-5-(2-pyridyl)pyrazoles and Related Pyrazoles
Figure 3. Representation of the π-stacking of the arenes in the solid
state of 3-(3,4,5-trimethylphenyl)-5-(2-pyridyl)pyrazole (2c). The car-
bon atoms and N-bound hydrogen atoms are shown with arbitrary ra-
dii, whereas carbon-bound hydrogen atoms are neglected for clarity
reasons.
Scheme 2. Hitherto unknown aggregation patterns of structure types
IIpz–py/pz (dimeric, intermolecular hydrogen bridges between pyrazole
bases as well as between pyrazole and pyridyl bases) and the strand
structure type IVpz–py
.
electronic effects of the substitents play no key role for the
pyrazole chemistry. According to the small structural varia-
tions, also the NMR parameters of the pyrazole fragments vary
only within narrow ranges.
Aggregation of these compounds occurs by hydrogen brid-
ges and diverse oligomeric and polymeric structures are pos-
sible, depending on the substituent at 3-position. Up to now,
monomeric molecules (type I) were never observed in the crys-
talline state but in the mass spectrum such species dominate.
The following secondary structures were found in the solid for
substituted 5-(2-pyridyl)pyrazoles and related compounds:
Type I: Monomeric molecules are observed in the gaseous
phase but not in the crystalline phase.
In addition to these structures a coplanar alignment of the
dimers in the solid state is realized for planar derivatives with
extended aromatic systems. This π-stacking lowers the solubil-
ity in common organic solvents as does the formation of one-
dimensional polymeric aggregates. Aryl groups with ortho
substituents are turned out of the pyrazole plane and π-stacking
seems to be less favored.
Experimental Section
Type II: Dimeric molecules with intermolecular N–H···N hy-
drogen bridges between pyrazole bases (type IIpz–pz) and be-
tween pyrazole and pyridyl units (type IIpz–py) were observed
as well as a combination of both (type IIpz–py/pz).
Type III: Tetrameric aggregates were only observed for 3-
adamantyl-5-(2-pyridyl)pyrazole (type IIIpz–pz) and 3-furanyl-
5-(2-pyridyl)pyrazole (type IIIpz–py/pz). There are no represen-
tatives with aryl groups in 3-position.
Type IV: Strand structures are built with the hydrogen atom
bound at N2. This primary structure eases the rotation at the
C5–C51 bond and allows a trans arrangement of the pyrazole
and pyridyl bases enabling formation of one-dimensional coor-
General Remarks: All manipulations were carried out in a nitrogen
atmosphere under anaerobic conditions. Prior to use, all solvents were
thoroughly dried and distilled in an inert gas atmosphere. 1H NMR
and 13C{1H} NMR spectra were recorded at ambient temperature with
Bruker AC 200, AC 400, or AC 600 spectrometers. The numbering
scheme for the assignment of the resonances is depicted in Table 1.
All spectra were referenced to the deuterated solvent as an internal
standard. EI-mass spectra were obtained with Finnigan MAT SSQ 710
or ThermoFinnigan MAT95XL systems. IR measurements were car-
ried out with a Perkin-Elmer System 2000 FT-IR. Decomposition and
melting points were measured with a Reichert-Jung Apparatus Type
302102. The pyrazoles 2a,[8,9] 2g,[11,12] 2l,[5,9] 2q,[10] and 2r[10] were
prepared earlier and are included in our discussions.
dination polymers of type IVpz–py
.
General Method for the Synthesis of 1,3-Substituted Propane-1,3-
diones (1): Carboxylate ester and NaH in a 1:1.2 ratio were suspended
in toluene. After the mixture was cooled to 0 °C, an equimolar amount
of the ketone was added. The reaction was warmed to ambient tem-
perature and an exothermic reaction took place. The reaction mixture
was stirred for additional 12 h at room temp. and afterwards heated
for 4 h at 80 °C in order to get a higher conversion. Thereafter, all
volatiles were removed in vacuo and the residue was quenched with a
1:1 mixture of water and acetic acid. The precipitate was recrystallized
Increasing bulkiness of the aryl groups in 3-aryl-5-(2-pyr-
idyl)pyrazoles alters the structures from type IIpz–pz (aryl = Ph,
para-tolyl) over type IIpz–py/pz (aryl = 3,4,5-trimethylphenyl,
1-pyrenyl) and type IIpz–py (aryl = duryl, 2-pyridyl) finally to
type IVpz–py [aryl = mesityl, 2,4,6-tri(isopropyl)phenyl, naph-
thyl, 9-anthracenyl]. The structure types IIpz–py/pz and
IVpz–py were observed for the first time for 5-(2-pyridyl)pyr-
azoles (Scheme 2).
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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Date: 06-02-14 11:07:16
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M. Westerhausen et al.
ARTICLE
Table 3. Preparative details for the synthesis of 3-aryl-5-(2-pyridyl)pyrazoles 2 and related compounds.
Pyrazole 2
Group at C3
Group at C5
Net weight
m /g
Product yield
Yield /%
n /mmol
m /g
n /mmol
2b
2c
2d
2e
2f
2h
2i
C6H4-4-Me
C6H2-3,4,5-Me3
C6H2-2,4,6-Me3
C6H-2,3,5,6-Me4
C6H2-2,4,6-iPr3
1-naph
9-anth
2-anth
2-flu
1-pyr
2-py
2-py
2-py
2-py
2-py
2-py
2-py
2-py
2-py
2-py
pyraz
2-quin
1-isoquin
5.1
5.1
21
19
38.9
82
32
48
75.1
69
98.4
39
89.5
71
87.5
81.1
89.5
87.3
89.4
88.9
2.25
3.77
7.07
22.9
4.3
18.17
2.6
1.9
9.21
11.5
22.3
8.35
2.01
9.6
14.4
26.8
80.4
12
67
8.1
10.4
23
11.1
20.6
3.7
2.2
11.5
13
75
11.4
6.8
36.7
37.2
115
34
2j
5.9
2k
2m
2n
2o
2p
29.8
33.3
100
30.7
7.4
Ph
Ph
Ph
26
9.48
2.3
8.4
from hot ethanol and purity of 1 was verified with spectroscopic meth-
ods (preparative details see Table S1 in the Supporting Information).
5-(2-Pyridyl)-3-(2,4,6-trimethylphenyl)-2H-pyrazole (2d): Yellow
1
crystals. M.p.: 149.6 °C. H NMR (600 MHz, [D8]THF, 298 K): δ =
4
12.26 (s, 1 H, NH), 8.53 [dd, 3J(H,H) = 4.8, J(H,H) = 1.0 Hz, 1 H,
3
3
General Procedure for the Synthesis of 3,5-Substituted Pyrazoles
(2): 1,3-Substituted-propane-1,3-diones were dissolved in ethanol and
hydrazine hydrate (1:1 ratio) was added. The mixture was refluxed for
4 h. All volatiles were removed in vacuo and the residue was recrys-
tallized from hot toluene yielding a pure product of 2 (Table 3).
C(55)H], 7.98 [d, J(H,H) = 7.9 Hz, 1 H, C(52)H], 7.70 [dt, J(H,H)
= 7.6, 4J(H,H) = 1.8 Hz, 1 H, C(53)H], 7.15 (dd, 3J(H,H) = 6.1,
4J(H,H) = 1.1 Hz, 1 H, C(54)H], 6.92 [s, 2 H, C(33)H], 6.78 [s, 1 H,
C(4)H], 2.29 [s, 3 H, C(341)H], 2.13 [s, 6 H, C(321)H]. 13C{1H} NMR
(150 MHz, [D8]THF, 298 K): δ = 153.0 (C5), 149.8 (C55), 145.2 (C3),
138.3 (C51), 138.2 (C32), 136.7 (C53), 129.8 (C31), 128.9 (C34),
128.7 (C33), 120.9 (C54), 119.8 (C52), 104.7 (C4), 21.1 (C321), 20.5
(C341). MS (EI, m/z%): 263[M]+, 100%), 247 [M-CH3]+, 10%), 232
[M-2*CH3]+, 8%), 218 [M-3*CH3]+,16%), 144 ([M-C9H11]+, 100%).
C17H17N3 (263.3): calcd. C 77.54, H 6.51, N 15.96%; found: C 76.56,
H 6.66, N 15.39%. IR: ν˜ = 3142 (m), 3082 (m), 2977 (m), 2960 (m),
2916 (m), 2855 (m), 2831 (m), 2745 (m), 1597 (s), 1564 (s), 1504
(s),1462 (s), 1442 (m), 1395 (m), 1376 (m), 1267 (m), 1227 (m),
1194(m), 1153 (w), 1103 (w), 1088 (w), 1037(w), 1004 (s), 963 (s),
916 (s), 848 (s), 785 (s), 750 (s), 713 (w), 699 (w), 687(w), 631 (s),
577 (s), 551 (s), 515 (s), 413 (s), 404(s) cm–1.
Physical Data of the Pyrazoles:
5-(2-Pyridyl)-3-(p-tolyl)pyrazole (2b): Colorless crystals. M.p.:
173.2 °C. 1H NMR (600 MHz, CDCl3, 298 K): δ = 10.90 (s, 1 H, NH),
3
8.68 [d, J(H,H) = 4.8 Hz, 1 H, C(55)H], 7.75 –7.71 [m, 4 H, C(32/
52/ 53)H], 7.24–7.21 [m, 3 H, C(33/ 54)H], 7.03 [s, 1 H, C(4)H], 2.37
[s, 3 H, C(341)H]. 13C{1H} NMR (150 MHz, CDCl3, 298 K): δ =
151.3 (C3), 149.3 (C55), 148.8 (C51), 144.9 (C5), 137.8 (C34), 137.0
(C53), 129.6 (C31), 129.4 (C33), 125.5 (C32), 122.8 (C54), 120.1
(C52), 100.3 (C4), 21.2 (C341). MS (EI, m/z%): 235 ([M]+, 100%),
206 ([M – HN2]+, 62%). C15H13N3 (235.3): calcd. C 76.57, H 5.57,
N 17.86%; found: C 76.28, H 5.64, N 17.61%. IR: ν˜ = 3200 (b), 3067
(b), 3013 (b), 2962 (b), 2919 (b), 2855 (b), 1598 (w), 1565 (w), 1532
(w), 1471 (m), 1453 (m), 1423 (m), 1375 (w), 1314 (w), 1297 (w),
1261 (w), 1230 (w), 1177 (m), 1150 (w), 1115 (m), 1093 (m), 1048
(m), 1019 (m), 995 (m), 974 (m), 957 (m), 883 (w), 844 (w), 822 (m),
800 (s), 772 (s), 739 (m), 714 (m), 685 (w), 661 (m), 620 (w), 511
(m), 494 (s) cm–1.
5-(2-Pyridyl)-3-(2,3,5,6-tetramethylphenyl)pyrazole (2e): Colorless
crystals. M.p.: 233.5 °C. 1H NMR (400 MHz, CDCl3, 298 K): δ = 8.64
3
3
[d, J(H,H) = 4.1 Hz, 1 H, C(55)H], 7.92 [d, J(H,H) = 7.9 Hz, 1 H,
C(52)H], 7.72 [dt, 3J(H,H) = 7.8, 4J(H,H) = 1.4 Hz, 1 H, C(53)H],
7.24 [m, 1 H, C(54H)], 7.04 [s, 1 H, C(34)H], 6.79 [s, 1 H, C(4)H],
2.25 [s, 6 H, C(331)H], 2.02 [s, 6 H, C(321)H]. 13C{1H} NMR
(100 MHz, CDCl3, 298 K): δ = 151.0 (C51), 149.4 (C55), 148.9 (C5),
147.3 (C3), 137.0 (C53), 134.1 (C33), 133.9 (C32), 132.1 (C34), 131.2
(C31), 122.8 (C54), 120.2 (C52), 104.6 (C4), 20.2 (C331), 17.1
(C321). MS (EI, m/z%): 277 ([M]+, 88%). C18H19N3 (277.4): calcd.:
C 77.95, H 6.90, N 15.15%; found: C 78.12, H: 7.15, N 15.16%. IR:
ν˜ = 3235 (b), 3061 (b), 2998 (b), 2959 (b), 2920 (b), 2862 (b), 1600
(w), 1568 (w), 1490 (w), 1449 (m), 1393 (w), 1282 (w), 1184 (w),
1156 (w), 1139 (w), 1024 (w), 999 (w), 971 (w), 962 (w), 805 (w),
781 (m), 732 (m), 696 (w), 655 (w), 625 (w), 596 (w), 467 (w) cm–1.
5-(2-Pyridyl)-3-(3,4,5-trimethylphenyl)pyrazole (2c): Colorless
crystals. M.p.: 186.8 °C. 1H NMR (400 MHz, CDCl3, 298 K): δ =
3
11.72 (s, 1 H, NH), 8.62 [d, J(H,H) = 4.8 Hz, 1 H, C(55)H], 7.70–
3
4
7.68 [m, 1 H, C(52)H], 7.64 [dt, J(H,H) = 7.7, J(H,H) = 1.7 Hz, 1
H, C(53)H], 7.34 [s, 2 H, C(32)H], 7.15–7.11 [m, 1 H, C(54H), 6.96
[s, 1 H, C(4)H], 2.24 [s, 6 H, C(331)H], 2.10 [s, 3 H, C(341)H].
13C{1H} NMR (100 MHz, CDCl3, 298 K): δ = 149.4 (C55), 137.0
(C34), 136.8 (C53), 135.1 (C33), 124.9 (C32), 122.8 (C54), 120.2
5-(2-Pyridyl)-3-(2,4,6-triisopropylphenyl)-2H-pyrazole (2f): Color-
(C52), 100.4 (C4), 20.7 (C331), 15.3 (C341). MS (EI, m/z%): 263 less crystals. M.p.: 184.4 °C. 1H NMR (400 MHz, [D6]DMSO,
([M]+, 100%), 248 ([M-CH3]+, 30%), 234 ([M – HN2]+, 26%). 298 K): δ = 12.94 (s, 1 H, NH), 8.58 [m, 1 H, C(55)H], 8.00 [m, 1 H,
C17.88H18N3 (274.85): calcd. C 78.15, H 6.54, N 15.28%; found: C
78.40, H 6.60, N 15.35%. IR: ν˜ = 3136 (b), 3105 (b), 2935 (b), 2912 C(54H)], 7.11 [s, 2 H, C(33)H], 6.76 [s, 1 H, C(4)H], 2.92 [sept,
C(52)H], 7.85 [t, 3J(H,H) = 7.3 Hz, 1 H, C(53)H], 7.30 [m, 1 H,
(b), 2854 (b), 1597 (w), 1581 (w), 1566 (w), 1450 (m), 1427 (w), 1377
3J(H,H) = 6.9 Hz, 1 H, C(341)H], 2.60 [m, 2 H, C(321)H], 1.24 [d,
(w), 1296 (w), 1285 (w), 1188 (w), 1150 (w), 1111 (w), 1069 (w), 3J(H,H) = 6.9 Hz, 6 H, C(3411)H], 1.09 [m, 12 H, C(3211)H]. 13C{1H}
1049 (w), 1007 (m), 999 (m), 983 (w), 964 (w), 895 (w), 860 (m), 840 NMR (100 MHz, [D6]DMSO, 298 K): δ = 152.9 (C51), 151.7 (C5),
(w), 764 (m), 733 (m), 695 (w), 660 (w), 621 (w) cm–1.
150.1 (C34), 149.6 (C55), 141.5 (C31), 137.2 (C53), 125.7 (C32),
6
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3-Aryl-5-(2-pyridyl)pyrazoles and Related Pyrazoles
122.9 (C54), 120.8 (C33), 119.7 (C52), 104.9 (C4), 34.3 (C341), 30.7
3-(2-Fluorenyl)-5-(2-pyridyl)pyrazole (2k): Yellow powder. Dec.
Ͼ266 °C. 1H NMR (600 MHz, [D6]DMSO, 298 K): δ = 13.56 (s, 1
(C321), 24.5 (C3211/3411). MS (EI, m/z%): 347 ([M]+, 30%), 304
([M-C3H7]+, 28%). C23H29N3 (347.5): calcd.: C 79.50, H 8.41, N H, NH); 8.62 [d, 3J(H,H) = 4.1 Hz, 1 H, C(55)H], 8.08 [s, 1 H,
12.09%; found: C 79.25, H 8.68, N 12.28%. IR: ν˜ = 3185 (b), 3144
C(flu)H], 7.96 [m, 2 H, C(flu)H], 7.90 [m, 3 H, C(52/ flu)H], 7.59 [d,
(b), 3042 (b), 2957 (m), 2930 (m), 2868 (m), 1597 (m), 1564 (w), 3J(H,H) = 7.4 Hz, 1 H, C(flu)H], 7.37 [t, 3J(H,H) = 7.4 Hz 1 H,
1504 (w), 1461 (m), 1400 (w), 1361 (w), 1316 (w), 1275 (w), 1222 C(53)H], 7.35–7.30 [m, 3 H, C(4/ 54/ flu)H], 3.98 (s, 2 H, CH2).
(w), 1170 (w), 1149 (w), 1093 (w), 997 (m), 966 (m), 962 (m), 878 13C{1H} NMR (150 MHz, [D6]DMSO, 298 K): δ = 149.4 (C55),
(m), 817 (w), 785 (m), 744 (m), 713 (w), 653 (w), 632 (w), 623 (w), 143.3, 140.8, 137.1, 126.9, 125.2, 124.1, 122.9, 121.9, 120.4, 120.1,
513 (w), 405 (w) cm–1.
100.9 (C4), 36.5 (CH2). MS (EI, m/z%): 309 ([M]+, 100%), 280 ([M –
HN2]+, 40%). C21H15N3 (309.3): calcd. C 81.53, H 4.89, N 13.58%;
found: C 80.18, H 4.94, N 13.48%. IR: ν˜ = 3118 (b), 3130 (b), 3051
(b), 1595 (w), 1566 (w), 1470 (w), 1449 (m), 1402 (w), 1388 (w),
1301 (m), 1194 (w), 1150 (w), 1057 (w), 997 (w), 975 (m), 962 (w),
954 (w), 889 (w), 864 (w), 833 (w), 807 (m), 780 (m), 768 (s), 734
(s), 713 (m), 622 (w), 585 (w), 536 (m), 514 (w), 499 (w), 472 (w),
423 (m), 404 (m) cm–1.
3-(1-Naphthyl)-5-(2-pyridyl)-2H-pyrazole (2h): Colorless crystals.
1
Dec. Ͼ 139 °C. H NMR (600 MHz, [D6]DMSO, 298 K): δ = 13.78
3
(s, 1 H, NH); 8.64 [d, J(H,H) = 4.6 Hz, 1 H, C(55)H], 8.48 [m, 1 H,
C(39)H], 8.03 [d, 3J(H,H) = 7.8 Hz, 1 H, C(52)H], 7.99–7.96 [m, 2 H,
C(34/ 36)H], 7.88 [t, 3J(H,H) = 7.7 Hz, 1 H, C(53)H], 7.75 [d, 3J(H,H)
= 7.0 Hz, 1 H, C(32)H], 7.60–7.53 [m, 3 H, C(33/ 37/ 38)H], 7.34 [t,
3J(H,H) = 6.1 Hz, 1 H, C(54)H], 7.24 [s, 1 H, C(4)H]. 13C{1H} NMR
(150 MHz, [D6]DMSO, 298 K): δ = 149.4 (C55), 137.1 (C53), 133.5
(C31), 130.6 (C40), 128.4 (C34/ 36), 126.9 (C32), 126.6, 126.1, 125.6
3-(1-Pyrenyl)-5-(2-pyridyl)pyrazole (2m): Yellow crystals. Dec.
Ͼ237 °C. 1H NMR (600 MHz, [D6]DMSO, 298 K): δ = 13.94 (s, 1
(C39), 125.5 (C38), 122.8 (C54), 119.8 (C52), 104.4 (C4). MS (EI, H, NH), 13.69 (s, 1 H, NH‘), 9.07 [d, 3J(H,H) = 9.3 Hz, 1 H,
m/z%): 271 ([M]+, 100%). C18H13N3 (271.3): calcd. C79.68, H 4.83,
N 15.49%; found: C 79.44, H 5.15, N 15.36%. IR: ν˜ = 3145 (b), 3046
C(pyr)H], 8.69 [d, J(H,H) = 4.1 Hz, 1 H, C(15)H], 8.44–8.19 [m, 12
3
H, C(12/ pyr)H], 8.13–8.06 [m, 3 H, C(pyr)H], 8.01 [d, 3J(H,H) =
3
(b), 2963 (b), 2920 (b), 2803 (b), 1599 (w), 1562 (w), 1512 (w), 1461 7.7 Hz, 1 H, C(pyr)H], 7.94 [t, J(H,H) = 7.3 Hz, 1 H, C(13)H], 7.89
(w), 1416 (w), 1406 (w), 1274 (w), 1261 (w), 1151 (w), 1001 (w), 961 [t, 3J(H,H) = 7.4 Hz, 1 H, C(13‘)H], 7.50 [s, 1 H, C(4)H], 7.40 [t,
(w), 906 (w), 783 (m), 769 (m), 746 (m), 711 (w), 627 (w), 566 (w), 3J(H,H) = 6.0 Hz, 1 H, C(14)H], 7.35 [t, 3J(H,H) = 5.8 Hz, 1 H,
426 (m) cm–1.
C(14‘)H], 7.30 [s, 1
H, C(4‘)H]. 13C{1H} NMR (150 MHz,
[D6]DMSO, 298 K): δ = 152.3, 152.0, 151.8, 149.5 (C55), 149.3
(C55‘), 148.0, 142.8, 142.3, 137.5, 136.9, 131.0, 130.4, 130.3, 128.8,
128.5, 128.1, 128.0, 127.7, 127.6, 127.5, 127.4, 127.3, 126.7, 126.4,
125.8, 125.7, 125.5, 125.3, 125.0, 124.8, 124.4, 124.2, 124.1, 123.8,
123.2 (C54), 122.7 (C54‘), 120.3, 119.4, 105.0 (C4). MS (ESI, m/z%):
713 ([2*M+Na]+, 100%), 368 ([M + Na]+, 82%), 346 ([M + H]+,
44%). C24H15N3 (309.3) calcd. C 83.46, H 4.38, N 12.17%; found: C
83.16, H 4.70, N 12.61%. IR: ν˜ = 3213 (b), 3149 (b), 3039 (b), 1592
(m), 1566 (m), 1500 (w), 1444 (m), 1433 (m), 1405 (m), 1365 (m),
1321 (m), 1307 (w), 1283 (w), 1260 (w), 1240 (w), 1175 (w), 1151
(w), 1124 (w), 1085 (w), 1066 (w), 1045 (w), 1034 (w), 992 (w), 969
(w), 900 (w), 883 (w), 840 (w), 819 (w), 754 (s), 738 (w), 713 (w),
692 (w), 679 (w), 657 (w), 618 (w), 611 (w), 579 (w), 549 (w), 534
(w), 511 (w), 500 (w), 481 (w), 453 (w), 440 (w), 429 (w), 417 (w)
cm–1.
3-(9-Anthracenyl)-5-(2-pyridyl)-2H-pyrazole (2i): Brown crystals.
1
M.p.: 211.9 °C. H NMR (600 MHz, CDCl3, 298 K): δ = 11.44 (s, 1
H, NH), 8.66 [d, 3J(H,H) = 6.3 Hz, 1 H, C(55)H], 8.52 [s, 1 H,
3
3
C(38)H], 8.03 [d, J(H,H) = 8.5 Hz, 2 H, C(36)H], 7.94 [d, J(H,H) =
3
8.8 Hz, 2 H, C(33)H], 7.89 [d, J(H,H) = 7.8 Hz, 1 H, C(52)H], 7.75
[dt, J(H,H) = 7.7, J(H,H) = 1.6 Hz, 1 H, C(53)H], 7.46 [t, J(H,H)
= 7.4 Hz, 2 H, C(35)H], 7.40 [dt, J(H,H) = 7.7, J(H,H) = 1.1 Hz, 2
3
4
3
3
4
3
4
H, C(34)H], 7.25 [dt, J(H,H) = 6.6, J(H,H) = 1.1 Hz, 1 H, C(54)H],
7.11 [s, 1 H, C(4)H]. 13C{1H} NMR (150 MHz, CDCl3, 298 K): δ =
149.6 (C55), 137.1 (C53), 131.4 (C32/37), 128.5 (C36), 128.3 (C38),
126.4 (C33), 126.2 (C34), 125.4 (C35), 123.0 (C54), 120.4 (C52),
106.9 (C4). MS (EI, m/z%): 321([M]+, 96%), 320 ([M – H]+, 100%),
291 ([M – H2N2]+, 42%). C22H15N3 (321.4): calcd.: C 82.22, H 4.70,
N 13.08%; found: C 81.44, H 5.13, N 13.49%. IR: ν˜ = 3188 (b), 3134
(b), 3060 (b), 2987 (b), 2929 (b), 2878 (b), 2843 (b), 1624 (w), 1596
(m), 1563 (w), 1504 (m), 1470 (w), 1443 (w), 1424 (w), 1404 (m), 3-Phenyl-5-pyrazinylpyrazole (2n): Yellow powder. M.p.: 168.8 °C.
1330 (m), 1281 (w), 1148 (w), 1087 (w), 1049 (w), 1018 (w), 998 (m),
960 (m), 913 (w), 901 (m), 892 (m), 844 (m), 787 (s), 732 (s), 708
(m), 681 (m), 639 (w), 623 (m), 605 (m), 550 (m), 512 (w), 477 (w), [d, J(H,H) = 2.5 Hz, 1 H, C(55)H], 7.87 [d, J(H,H) = 7.5 Hz, 2 H,
406 (m) cm–1.
1H NMR (400 MHz, [D6]DMSO, 298 K): δ = 9.23 [d, 4J(H,H) =
3
1.1 Hz, 1 H, C(52)H], 8.68 [t, J(H,H) = 1.9 Hz, 1 H, C(54)H], 8.59
3
3
C(32)H], 7.47 [t, 3J(H,H) = 7.6 Hz, 2 H, C(33)H], 7.41 [s, 1 H,
C(4)H], 7.36 [t, 3J(H,H) = 7.4 Hz, 1 H, C(34)H]. 13C{1H} NMR
(100 MHz, [D6]DMSO, 298 K): δ = 147.2 (C3), 146.7 (C5), 144.7
(C54), 143.9 (C55), 141.8 (C52), 130.9 (C31), 129.4 (C33), 128.6
(C34), 125.7 (C32), 102.0 (C4). MS (EI, m/z%): 222 ([M]+, 100%),
193 ([M – HN2]+, 70%) C13H10N4 (222.3): calcd. C 70.26, H 4.54, N
25.21%; found: C 68.47, H 4.57, N 25.40%. IR: ν˜ = 3201 (b), 3050
(b), 1593 (m), 1565 (m), 1522 (m), 1467 (m), 1447 (m), 1411 (m),
1376 (m), 1318 (m), 1301 (m), 1268 (m), 1235 (w), 1189 (m), 1158
(m), 1140 (m), 1111 (m), 1076 (m), 1056 (m), 1044 (m), 1014 (m),
974 (m), 956 (m), 916 (m), 840 (m), 807 (s), 760 (s), 691 (s), 682 (s),
527 (m), 508 (s) cm–1.
3-(2-Anthracenyl)-5-(2-pyridyl)pyrazole (2j): Yellow powder.
Dec.Ͼ 267 °C. 1H NMR (400 MHz, [D6]DMSO, 298 K): δ = 13.83
(s, 1 H, NH), 8.67 [m, 1 H, C(55)H], 8.61 [s, 1 H, C(anth)H], 8.57 [d,
3J(H,H) = 6.0 Hz, 1 H, C(anth)H], 8.29–7.92 (m, 8 H, CH), 7.55 [s, 1
H, C(4)H], 7.52 [m, 1 H, C(anth)H], 7.40 [m, 1 H, C(54)H]. 13C{1H}
NMR (100 MHz, [D6]DMSO, 298 K): δ = 149.6 (C55), 137.9, 134.9,
132.2, 131.8, 131.7, 131.1, 129.2, 128.6, 128.5, 126.7, 126.5 126.3,
126.1, 124.1, 123.8, 123.5, 120.3, 101.9 (C4). MS (EI, m/z%):
321([M]+, 100%), 291 ([M – H2N2]+, 36%). C22H15N3 (321.4): calcd.
C 82.22, H 4.70, N 13.08%; found: C 80.85, H 5.02, N 13.11%. IR:
ν˜ = 3236 (b), 3135 (b), 3052 (b), 1628 (w), 1598 (w), 1567 (w), 1534
(w), 1499 (w), 1480 (w), 1451 (w), 1433 (w), 1400 (w), 1312 (w),
1280 (w), 1158 (w), 1051 (w), 999 (w), 978 (w), 956 (w), 920 (w),
5-(2-Quinolyl)-3-phenylpyrazole (2o): Colorless powder. M.p.:
233.5 °C. 1H NMR (400 MHz, [D6]DMSO, 298 K): δ = 13.77 (s, 1 H,
911 (w), 898 (m), 873 (m), 804 (m), 780 (m), 745 (m), 719 (w), 657 NH), 8.44 [d, 3J(H,H) = 8.6 Hz, 1 H, C(53)H], 8.17 [m, 1 H,
(w), 623 (w), 606 (w), 550 (w), 521 (w), 505 (w), 471 (w), 450 (w)
cm–1.
3
3
C(52)H], 8.08 [d, J(H,H) = 8.4 Hz, 1 H, C(58)H], 7.98 [d, J(H,H) =
3
8.0 Hz, 1 H, C(55)H], 7.92 [d, J(H,H) = 7.6 Hz, 2 H, C(32)H], 7.79
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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7

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/KAP1
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M. Westerhausen et al.
ARTICLE
[t, 3J(H,H) = 7.6 Hz, 1 H, C(57)H], 7.59 [t, 3J(H,H) = 7.4 Hz, 1 H, ite-monochromatized Mo-Kα radiation. Data were corrected for Lo-
C(56)H], 7.51 [s, 1 H, C(4)H], 7.48 [t, 3J(H,H) = 7.3 Hz, 2 H, rentz and polarization effects but not for absorption effects.[14,15] The
C(33)H], 7.37 [t, 3J(H,H) = 7.3 Hz, 1 H, C(34)H]. 13C{1H} NMR structures were solved by Direct Methods (SHELXS[16]) and refined
2
(100 MHz, [D6]DMSO, 298 K): δ = 147.9 (C54), 137.4 (C53), 130.5
by full-matrix least-squares techniques against Fo (SHELXS-97[16]).
(C57), 129.4 (C33), 129.1 (C59), 128.5 (C34/ 55), 127.7 (C59), 126.8 With the exception of the amine-group the hydrogen atoms of 2c were
(C56), 125.7 (C32), 118.9 (C52), 102.0 (C4). MS (EI, m/z%): 271 included at calculated positions with fixed thermal parameters. All
([M]+, 100%), 241 ([M – H2N2]+, 96%), 128 ([M-C9H7N2]+, 38%). other hydrogen atoms were located by difference Fourier synthesis and
C18H13N3 (271.3): calcd. C 79.68, H 4.83, N 15.49%; found: C 79.46,
refined isotropically. The crystal structure of 2c contains solvent-
H 4.98, N 15.63%. IR: ν˜ = 3257 (b), 3059 (b), 1601 (m), 1559 (w), accessible voids (351 Å3 per unit cell) filled with disordered solvent
1498 (w), 1431 (m), 1420 (w), 1333 (w), 1315 (w), 1249 (w), 1222 molecules. Their contribution to the structure factors was secured by
(w), 1174 (w), 1074 (w), 1056 (w), 1027 (w), 1016 (w), 994 (m), 958 back-Fourier transformation using the Squeeze routine of Platon re-
(m), 936 (w), 914 (w), 831 (m), 805 (m), 788 (m), 761 (m), 749 (m), sulting in 58 electrons/unit cell.[17]. The crystal of 2h was a non-
689 (m), 638 (w), 626 (w), 595 (w), 533 (w), 526 (w), 509 (m), 478 merohedral twin. The twin law was determined by PLATON[17] to (1.0,
(m), 443 (w) cm–1.
0.0, 0.802) / 0.0, –1.0, 0.0 / 0.0, 0.0, –1.000). The contribution of the
main component was refined to 0.454(2). All other hydrogen atoms
were calculated at ideal positions with fixed thermal parameters. Crys-
tallographic data as well as structure solution and refinement details
are summarized in Table 4, Table 5, and Table 6. The program XP (Sie-
mens Analytical X-ray Instruments, Inc.)[18] was used for structure
representations.
5-(1-Isoquinolinyl)-3-phenylpyrazole (2p): Colorless crystals. M.p.:
208.4 °C. 1H NMR (400 MHz, [D6]DMSO, 298 K): δ = 13.72 (s, 1 H,
NH), 8.60 [d, 3J(H,H) = 5.6 Hz, 1 H, C(53)H], 8.02 [d, 3J(H,H) =
3
8.1 Hz, 1 H, C(56)H], 7.94 [d, J(H,H) = 7.4 Hz, 2 H, C(32)H], 7.83
3
3
[d, J(H,H) = 5.9 Hz, 1 H, C(54)H], 7.80 [d, J(H,H) = 7.8 Hz, 1 H,
3
3
C(55)H], 7.74 [t, J(H,H) = 7.6 Hz, 1 H, C(58)H], 7.49 [t, J(H,H) =
7.6 Hz, 2 H, C(33)H], 7.44 [s, 1 H, C(4)H], 7.37 [t, 3J(H,H) = 7.3 Hz,
1 H, C(34)H]. 13C{1H} NMR (100 MHz, [D6]DMSO, 298 K): δ =
Crystallographic data (excluding structure factors) for the structures in
142.4 (C53), 137.0 (C52), 130.7 (C55), 129.4 (C33), 128.4 (C34/ 58), this paper have been deposited with the Cambridge Crystallographic
127.6 (C56), 125.8 (C32), 120.9 (C54), 104.6 (C4). MS (EI, m/z%): Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
271 ([M]+, 100%), 241 ([M – H2N2]+, 100%). C18H13N3 (271.3):
calcd. C 79.68, H 4.83, N 15.49%; found: C 79.21, H 5.10, N 15.69%.
IR: ν˜ = 3214 (b), 3069 (b), 3046 (b), 1621 (w), 1581 (w), 1552 (w),
1501 (w), 1462 (w), 1444 (m), 1418 (w), 1343 (m), 1208 (w), 1190
of the data can be obtained free of charge on quoting the depository
numbers CCDC-974524 for 2b, -974525 for 2c, -974526 for
2d, -974527 for 2e, -974528 for 2f, -974529 for 2h, -974530 for 2i,
-974531 for 2m, -974532 for 2p, -974533 for 1c, -974534 for 1e,
(w), 1076 (m), 1064 (w), 1032 (w), 960 (m), 947 (w), 915 (w), 877 -974535, for 1f, and -974536 for 1p (Fax: +44-1223-336-033; E-Mail:
(m), 838 (m), 828 (m), 814 (m), 802 (m), 764 (m), 753 (s), 691 (s),
663 (m), 648 (m), 574(w), 542 (m), 527 (m), 501(w), 481 (m), 469
(w), 439 (w), 424 (m), 411 (w) cm–1.
deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk).
Supporting Information (see footnote on the first page of this article):
Structure Determinations: The intensity data for the compounds Experimental details, spectroscopic data, and structure representations
were collected with a Nonius KappaCCD diffractometer, using graph- for the precursor β-diketones are provided.
Table 4. Crystal data and refinement details for the X-ray structure determinations for complexes 2b–2f.
2b
2c
2d
2e
2f
Formula
Fw /g·mol–1
T /°C
Crystal system
Space group
a /Å
b /Å
c /Å
α /°
β /°
C15H13N3
235.28
–140(2)
orthorhombic
Pca21
17.7678(4)
5.7562(1)
22.8442(3)
90
C17H18N3
263.34
C17H17N3
263.34
–140(2)
orthorhombic
Pbca
10.6916(2)
11.1353(2)
24.0063(4)
90
C18H19N3
277.36
C23H29N3
347.49
–140(2)
monoclinic
P21/n
11.7185(2)
19.3936(3)
18.7734(3)
90
94.783(1)
90
4251.66(12)
8
1.086
0.64
26353
a
–140(2)
triclinic
–140(2)
triclinic
¯
¯
P1
P1
12.5431(2)
13.5982(2)
19.6533(3)
85.895(1)
80.091(1)
66.649(1)
3031.65(8)
8
5.8672(2)
10.2727(4)
12.9789(5)
70.773(2)
78.845(2)
87.876(2)
724.38(5)
2
1.272
0.77
4772
2973
90
90
90
90
γ /°
V /Å3
2336.39(7)
8
1.338
0.82
12810
2858.05(9)
8
1.224
0.74
18052
Z
ρ /g·cm–3
μ /cm–1
Measured data
Data with I Ͼ 2σ(I)
1.154
0.73
a)
a)
10954
8639
4781
2849
7616
Unique data (Rint
)
5353/0.040
0.1047
0.0459
1.071
0.269/–0.213
974524
10954/0.0
0.1738
0.0670
1.072
0.373/–0.277
974525
3264/0.037
0.1101
0.0446
1.071
0.241/–0.186
974526
3275/0.017
0.1149
0.0443
1.065
0.266/–0.209
974527
9656/0.050
0.1427
0.0609
1.103
0.273/–0.360
974528
b)
wR2 (all data, on F2)
b)
R1 [I Ͼ 2σ(I)]
S
c)
Res. dens./e·Å–3
CCDC No.
a) Derived parameters do not contain the contribution of the disordered solvent. b) Definition of the R indices: R1 = (Σ||Fo|–|Fc||)/Σ|Fo|; wR2 =
{Σ[w(Fo –Fc ) ]/Σ[w(Fo ) ]}1/2 with w–1 = σ2(Fo )+(aP)2+bP; P = [2Fc +Max(Fo ]/3. c) S = {Σ[w(Fo –Fc ) ]/(No–Np)}1/2
.
2
2 2
2 2
2
2
2
2
2 2
8
www.zaac.wiley-vch.de © 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Z. Anorg. Allg. Chem. 0000, 0–0

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3-Aryl-5-(2-pyridyl)pyrazoles and Related Pyrazoles
Table 5. Crystal data and refinement details for the X-ray structure determinations for complexes 2h, 2i, 2m, and 2p.
2h
2i
2m
2p
Formula
Fw /g·mol–1
T /°C
Crystal system
Space group
a /Å
b /Å
c /Å
α /°
C18H13N3
271.31
–140(2)
monoclinic
P21/c
10.6280(3)
12.7577(2)
10.8629(3)
90
C22H15N3
321.37
–140(2)
monoclinic
P21/n
17.0169(2)
10.7677(2)
17.6722(3)
90
C24H15N3
345.39
–140(2)
monoclinic
C2/c
32.3564(14)
7.9995(4)
27.6859(12)
90
C18H13N3
271.31
–140(2)
monoclinic
P21/c
10.0313(2)
11.5282(2)
12.0962(3)
90
β /°
114.186(1)
90
1343.60(6)
4
1.341
0.82
90.004(1)
90
3238.13(9)
8
1.318
0.79
113.784(2)
90
6557.5(5)
16
1.399
0.84
103.199(1)
90
1361.89(5)
4
1.323
0.8
γ /°
V /Å3
Z
ρ /g·cm–3
μ /cm–1
Measured data
Data with I Ͼ 2σ(I)
3033
2696
18800
5807
15145
5931
8008
2642
Unique data (Rint
)
3033/0.0
0.1144
0.0473
1.151
0.292/–0.280
974529
7390/0.041
0.1194
0.0531
1.096
0.226/–0.241
974530
7093/0.033
0.1157
0.0530
1.125
0.244/–0.226
974531
3099/0.030
0.1070
0.0447
1.052
0.233/–0.229
974532
a)
wR2 (all data, on F2)
a)
R1 [I Ͼ 2σ(I)]
S
b)
Res. dens./e·Å–3
CCDC No.
2
2 2
2 2
2
2
2
a) Definition of the R indices: R1 = (Σ||Fo|–|Fc||)/Σ|Fo|; wR2 = {Σ[w(Fo –Fc ) ]/Σ[w(Fo ) ]}1/2 with w–1 = σ2(Fo )+(aP)2+bP; P = [2Fc +Max(Fo ]/
2
2 2
3. b) S = {Σ[w(Fo –Fc ) ]/(No–Np)}1/2
.
Table 6. Crystal data and refinement details for the X-ray structure determinations for complexes 1c, 1e, 1f, and 1p.
1c
1e
1f
1p
Formula
Fw /g·mol–1
T/°C
Crystal system
Space group
a /Å
b /Å
c /Å
α /°
β /°
C17H17NO2
267.32
–140(2)
triclinic
¯
P1
9.9920(3)
10.1824(3)
14.5825(4)
80.684(2)
71.777(1)
84.229(1)
1388.69(7)
4
1.279
0.84
8348
5240
C18H19NO2
281.34
–140(2)
triclinic
¯
P1
7.6612(2)
9.1801(3)
11.6107(4)
96.448(1)
107.337(2)
104.537(2)
738.90(4)
2
1.265
0.82
4636
2994
C23H29NO2
351.47
–140(2)
triclinic
¯
P1
9.8859(2)
10.4722(3)
10.9177(4)
104.079(2)
91.516(2)
113.949(2)
991.90(5)
2
1.177
0.74
5935
3827
C18H13NO2
275.29
–140(2)
orthorhombic
Pna21
17.4126(11)
14.7614(10)
5.2623(2)
90
90
90
γ /°
V /Å3
1352.59(14)
4
1.352
0.89
6875
Z
ρ /g·cm–3
μ /cm–1
Measured data
Data with I Ͼ 2σ(I)
2593
Unique data (Rint
)
6213/0.016
0.1324
0.0550
1.088
0.281/–0.200
974533
3309/0.016
0.1131
0.0437
1.035
0.308/–0.207
974534
4440/0.021
0.1302
0.0557
1.093
0.353/–0.234
974535
2977/0.033
0.1039
0.0483
1.167
0.177/–0.181
974536
a)
wR2 (all data, on F2)
a)
R1 [I Ͼ 2σ(I)]
S
b)
Res. dens./e·Å–3
CCDC No.
2
2 2
2 2
2
2
2
a) Definition of the R indices: R1 = (Σ||Fo|–|Fc||)/Σ|Fo|; wR2 = {Σ[w(Fo –Fc ) ]/Σ[w(Fo ) ]}1/2 with w–1 = σ2(Fo )+(aP)2+bP; P = [2Fc +Max(Fo ]/
2
2 2
3. b) S = {Σ[w(Fo –Fc ) ]/(No–Np)}1/2
.
versity in Jena. We also acknowledge the support by Ronny Tepper
and Stefanie Koch in the frame of their master studies.
Acknowledgements
B.S. thanks the Graduate Academy of the Friedrich Schiller University
Jena/Germany for a Ph.D. grant. We are grateful to the German Federal
Ministry of Economic Affairs and Technology for generous financial
support. Infrastructure of our institute was provided by the European
Regional Development Fund (EFRE) and the Friedrich Schiller Uni-
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© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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M. Westerhausen et al.
ARTICLE
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Received: December 10, 2013
Published Online: ᭿
10
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© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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3-Aryl-5-(2-pyridyl)pyrazoles and Related Pyrazoles
B. Schowtka, C. Müller, H. Görls,
M. Westerhausen* ........................................................... 1–11
Synthesis, Structures, and Spectroscopic Properties of 3-Aryl-
5-(2-pyridyl)pyrazoles and Related Pyrazoles
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
11