Molecular structure of di-aryl-aldimines by multinuclear magnetic resonance and X-ray diffraction

Article abstract of DOI:10.1016/S0022-2860(03)00279-5

The complete ¹H, ¹³C and ¹⁵N NMR analyses for a series of 25 diaryl-aldimines containing phenyl, pyridyl, pyrazolone and furanyl moieties are described herein. Detailed evaluation of substituent chemical shift and coupling constant effects showed that interaction between the lone pair of the pyrazolone carbonyl group or the nitrogen of 2-substitued pyridines with the aldimine hydrogen increases the ¹J_CH value and shifts the resonance signal for this hydrogen to high frequency, in the ¹H NMR spectra. The X-ray crystal structure analysis of pyrazolone substituted aldimines evidenced the planarity of the aryl groups which are conjugated with the C=N double bond. In the case of the N-(2-pyridinemethylene)-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one, two rotamers were observed in the same unit cell.

Full text of DOI:10.1016/S0022-2860(03)00279-5

Journal of Molecular Structure 655 (2003) 375–389
www.elsevier.com/locate/molstruc
Molecular structure of di-aryl-aldimines by multinuclear magnetic
resonance and X-ray diffraction
1
Ruben Montalvo-Gonzalez , Armando Ariza-Castolo
*
´
´
´ ´
Centro de Investigacion y de Estudios Avanzados del IPN. Apartado Postal, 14-740, 07000 Mexico D.F., Mexico
Received 10 October 2002; revised 9 April 2003; accepted 14 April 2003
Abstract
The complete 1H, 13C and 15N NMR analyses for a series of 25 diaryl-aldimines containing phenyl, pyridyl, pyrazolone and
furanyl moieties are described herein. Detailed evaluation of substituent chemical shift and coupling constant effects showed
that interaction between the lone pair of the pyrazolone carbonyl group or the nitrogen of 2-substitued pyridines with the
aldimine hydrogen increases the 1JCH value and shifts the resonance signal for this hydrogen to high frequency, in the 1H NMR
spectra. The X-ray crystal structure analysis of pyrazolone substituted aldimines evidenced the planarity of the aryl groups
which are conjugated with the CyN double bond. In the case of the N-(2-pyridinemethylene)-1,5-dimethyl-2-phenyl-1,2-
dihydro-pyrazol-3-one, two rotamers were observed in the same unit cell.
q 2003 Elsevier B.V. All rights reserved.
Keywords: 1H; 13C; 15N NMR; Aldimine; Weak interactions; X-ray
1. Introduction
have been widely recognized as important candidates
for applications in the field of nonlinear optics. They
have been analyzed primarily by vibrational and
electronic spectroscopy [4]. From the NMR point of
view, the ‘push–pull’ concept has been used to
account for their unusual 13C chemical shifts, where
one of the signals is shifted to high and the other to
low frequency [5]. These shifts are associated with a
redistribution of the electronic charge in the ethylenic
carbons and a decrease of the rotational barrier of the
CyC double bond [6].
Since aldimines were first synthesized in 1964 [1],
there has been a continued interest in the study of
compounds possessing carbon–nitrogen double
bonds due to the fact that they are precursors of
substances [2] with biological activity, as well as
stable and useful intermediates for the synthesis of
other substrates.
Carbon–carbon double bond systems having donor
and acceptor groups on opposite sides of the
molecules [3] exhibit the ‘push–pull effect’ and
The structure and spectroscopy data for a series of
25 aldimines containing phenyl or heterocyclic
substituents conjugated with the CyN double bond
(Scheme 1) were analyzed using multinuclear mag-
netic resonance and monocrystal X-ray diffraction.
The compounds described herein possess an iminic
*
Corresponding author. Tel.: þ52-55-57473727; fax: þ52-55-
544-77113.
E-mail address: aariza@mail.cinvestav.mx (A. Ariza-Castolo).
On leave from Facultad de Ciencias e Ingenierias UAN.
1
0022-2860/03/$ - see front matter q 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-2860(03)00279-5

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R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
376
Scheme 1. Substituted aldimines (R1–NyCH–R2).
bond, 1,2-disubstitued by weak electrondonor and
acceptor groups which allowed evaluation of sub-
stituent effects on 13C and 15N chemical shifts. As
expected, substituent chemical shift (SCS) effects are
larger in 15N than in 13C NMR. The present results
showed that resonance stabilization [7] alone is not
sufficient to secure a planar arrangement in these
systems due to abnormally large torsion angles for the
planes defined by the CyN and the aryl groups in both
solid state, determined by X-ray [8], and solution,
evidenced by NMR [9]. This distortion has been
explained theoretically [10], and our results suggest
that these systems can be stabilized by a stereo-
electronic interaction.
the basis of their distinct relaxation time and they
were confirmed by comparison within the same series.
15N NMR spectra were recorded using the INEPT
pulse sequence with and without proton decoupling
and assignments were based on HMQC 1H–15N
1
spectra. The H, 13C and 15N NMR have additive
substituent effects which are evident in the aldimine
moiety; the signals for the aromatic substituents
showed the characteristic chemical shifts.
SCS for the CHyN group were calculated from
the differences between the heteroaromatic substi-
tuent with the corresponding phenyl derivative.
These parameters were found to be additive and the
reference compound for estimation was 1a. The
average error for d1H was ,0.1 ppm, whilst for
d13C was ,0.5 ppm and for d15N was up to
2.4 ppm.
2. Results
The configuration of the CyN double bond was
elucidated based on the lone pair effect [12] and the
observed 1JCH value. The stereochemistry around the
carbon–nitrogen double bond was E for all
compounds.
NMR spectral analysis was based on multinuclear
experiments. Thus connectivity was established from
heteronuclear and homonuclear correlation spec-
troscopy (COSY and HETCOR 13C–1H). 1H and
13C spectral assignment was preformed by simulation
[11]. The quaternary carbons were distinguished on
Contrary to previous reports [8] of 1a, 2a, 3a and
4a, X-ray diffraction of compounds 1e, 2e, 3e, 4e and

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R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
377
5e showed a planar arrangement of the aryl groups
with the double bond CyN.
an electron-donor effect, as evidenced by the fact that
the signals are shifted to lower frequency. 15N
chemical shift reveled that a heterocyclic group
bonded to the imine carbon shifted the resonance to
high frequency, except for the furanyl group,
compounds 5a–5e, which evidenced an electrodona-
tion contribution. These effects were additive, as
shown in table 2 the C-4-pyridyl derivatives (4a to 4e)
experienced the largest shift, followed by the C-2-
pyridyl (2a–2e), and C-3-pyridyl (3a–3e), which
showed almost the same magnitude effect as the N-3-
pyridyl, but in opposite direction (compounds 1c, 2c,
3c, 4c and 5c). The largest shift to higher frequency
was observed in the pyrazolone derivatives (1e, 2e,
3e, 4e and 5e), followed by the furanyl group (5a–5e),
and the N-2-pyridyl derivatives (1b, 2b, 3b, 4b and
5b) while no effect was observed upon introduction of
The compounds were also analyzed by ultraviolet
and infrared spectroscopy.
3. Discussion
3.1. 13C NMR
The 13C NMR data for aldimines 1a to 5e are
summarized in Table 1. The chemical shift range for
the phenyl, pryridyl, pyrazolone or furanyl substitu-
ents is characteristic for each particular system and
depends on whether it is attached to the carbon or
nitrogen atom of the aldimine system. The imine
carbon showed smaller SCS than the nitrogen, the
furanyl group induced the largest effect (5a–5e)
shifted to low frequency (145–150 ppm); the remain-
ing substituents induced shifts to high frequency
(,3 ppm). The resonance of iminic carbons contain-
ing a phenyl group experienced larger shift effects
than those containing a pyridyl group. SCS were
estimated by subtracting the chemical shifts for the
molecule containing a heterocyclic substituent from
the corresponding phenyl analogue. These effects
were found to be additive (Table 2).
a N-4-pyridyl moiety (1d, 2d, 3d, 4d and 5d). The 15
N
substituent effects for the heterocyclic nitrogen ring
were negligible, except for pyrazolone derivatives 1e,
2e, 3e, 4e and 5e.
The value for the 2J(15N,1H) of the imine nitrogen
with the aldimine proton is in the range from 3.3 to
6.4 Hz, indicating that all imines had a E configur-
2
15
ation [13]. The Jð N; 1H) (Table 3) value with the
nitrogen of the pyridyl group depended on the position
of the substituent. 2-Substituted derivatives showed
values 12 ^ 1 Hz while 3- or 4-substitued showed
two bond couplings of 22 ^ 1 Hz, independently of
their position.
1
The one bond coupling constant, JCH (Table 1)
showed a trend and its particular value is character-
istic for the heterocycle. As previously noted for the
chemical shifts, an aryl group has a stronger effect on
the imine carbon than on nitrogen. The 2-pyridyl
3.3. 1H NMR
1
derivatives (2a–2e) exhibited the largest JCH value
(164–170 Hz), followed by the 4-pyridyl derivatives
4a–4e (162–169 Hz). A significant increment in 1JCH
value was observed upon substitution by pyrazolone
(1e, 2e, 3e, 4e and 5e) or 2-pyridyl groups (1b, 3b, 4b,
5b and 2a–2e) at the iminic nitrogen due to favorable
electronic interaction and the absence of steric
hindrance in these systems.
The 1H NMR spectra were resolved by simulation
3
as second order coupling system. Analysis of JHH
(Table 4) showed that the phenyl hydrogen had the
largest observed value, whilst the furanyl group had
the smallest. This value was relatively constant
regardless of the position of the substituent. The
long-range coupling constants (Table 4) also showed
small substituent effects.
3.2. 15NMR
The proton chemical shifts (Table 5) evidenced the
electron-donating character of the furanyl group
since, the resonances were shifted to a lower
frequency compared to those derivatives with a
phenyl group. The aldimine hydrogen in the pyrazo-
lone derivatives (1e, 2e, 3e, 4e and 5e) appeared at the
highest frequency and this was attributed to low steric
15N chemical shift effects were found to be larger
than 13C effects, except for furanyl derivatives,
compounds 5a–5e, which had the same SCS in both
nuclei. 15N NMR data are summarized in Table 3.
Substitution at the imine nitrogen by a heterocycle has

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R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
378
Table 1
13C NMR, chemical shifts and one bond H–13C coupling constants for aldimines 1–5
1
Comp.
CyN
R1
1
R2
10
2
3
4
5
6
20
30
40
50
60
1a
1b
1c
160.5
158.5
162.9
162.1
162.2
158.8
163.5
159.6
157.3
166.3
160.6
163.7
163.2
165.9
162.3
164.0
163.6
163.7
156.7
170.4
156.9
160.4
159.5
163.7
159.0
160.7
159.9
161.6
153.7
167.6
157.8
162.3
160.3
165.4
159.4
162.3
160.8
163.5
153.9
169.8
147.8
161.7
149.9
165.4
148.9
161.9
150.0
162.4
144.9
169.2
152.2
161.1
147.9
159.4
152.3
150.9
160.5
146.6
158.2
152.8
151.1
159.9
147.0
158.0
152.3
150.7
159.5
146.2
157.7
152.6
151.4
160.3
146.9
158.2
151.1
121.3
158.8
–
129.2
160.2
148.9
178.7
–
126.4
161.2
121.9
165.0
147.3
179.6
–
129.2
160.2
138.1
160.1
123.8
164.0
150.0
177.1
118.8
121.3
158.8
119.8
165.0
129.0
163.0
116.2
163.7
–
136.4
135.9
135.8
134.9
138.1
154.5
154.1
153.8
153.7
156.6
131.5
131.1
131.2
130.6
133.6
142.6
142.1
141.7
141.5
144.9
–
128.9
161.1
129.5
161.1
129.1
159.9
128.8
159.3
128.0
160.4
–
128.8
161.0
128.8
159.1
129.0
162.0
128.5
161.4
128.7
162.1
149.7
178.9
149.9
179.4
149.7
179.6
149.8
179.7
150.0
178.4
–
131.5
161.3
131.9
161.1
132.1
160.9
131.9
160.9
130.3
160.4
125.1
164.0
125.4
164.0
125.5
163.3
125.9
164.4
124.3
163.4
151.7
179.4
152.1
179.4
152.2
180.1
152.4
180.2
150.7
179.0
–
128.8
161.0
128.8
159.1
129.0
162.0
128.5
161.4
128.7
162.1
136.6
162.9
136.6
163.2
136.7
163.1
136.9
163.3
136.6
161.7
123.5
164.2
123.5
164.7
123.7
164.8
123.6
165.1
123.7
164.1
150.3
180.0
150.3
180.0
150.2
179.7
150.3
179.8
150.3
178.6
145.7
204.0
146.7
203.9
146.1
204.5
146.6
204.4
145.9
203.4
128.9
161.1
129.5
161.1
129.1
159.9
128.8
159.3
128.0
160.4
121.8
165.6
123.0
165.5
122.1
N.D.
122.4
167.3
121.6
163.9
134.6
164.1
135.1
164.6
135.1
164.5
134.9
164.7
134.2
164.4
122.1
164.3
122.4
166.0
121.9
164.5
122.1
164.5
121.5
162.1
–
142.7
179.6
116.2
163.7
161
1d
1ea
2a
2b
2c
150.0
177.1
–
–
121.1
159.8
–
129.2
160.4
148.9
178.6
–
126.7
161.5
122.4
164.7
147.7
129.2
160.4
138.1
161.1
123.7
165.6
150.7
178.7
118.1
121.1
159.8
119.6
164.9
127.6
166.8
115.6
164.7
–
–
–
–
–
142.9
179.8
115.6
164.7
160.6
N.D.
2d
2eb
3a
3b
3c
150.7
178.7
–
–
–
120.7
160.1
–
129.0
160.6
148.6
178.4
–
126.3
161.5
122.1
164.2
147.4
180.1
–
129.0
160.6
137.9
161.9
123.8
165.1
150.5
177.5
118.2
120.7
160.1
119.9
163.6
127.7
163.6
115.2
164.4
–
150.6
178.9
151.2
179.4
150.8
180.4
150.8
178.7
149.9
179.7
122.1
164.3
122.4
166.0
121.9
164.7
122.1
164.5
121.5
162.1
152.1
–
–
–
–
142.4
179.3
115.2
164.4
160.6
3d
3ec
4a
4b
4c
150.5
177.5
–
–
120.8
159.3
–
129.1
160.9
148.6
178.6
–
126.9
161.7
122.6
164.7
147.7
179.8
–
129.1
160.9
138.0
162.2
123.4
165.3
150.4
177.8
117.8
120.8
159.3
120.4
164.7
127.4
163.8
115.1
163.0
–
150.3
180.0
150.3
180.0
150.2
179.7
150.3
179.8
150.3
178.6
116.4
176.7
119.1
172.7
117.5
175.4
118.4
177.8
115.0
178.5
–
–
–
–
142.3
179.6
115.1
163.0
160.4
4d
4ed
5a
5b
5c
150.4
177.8
–
–
121.0
159.6
–
129.2
160.4
148.9
178.0
–
126.3
161.4
122.4
164.8
147.0
179.6
–
129.2
160.4
138.5
161.8
123.4
165.0
150.8
177.2
118.7
121.0
159.6
121.2
164.4
127.5
163.0
116.0
163.6
–
112.3
177.7
112.8
177.3
112.3
177.5
112.4
177.0
112.1
166.1
–
152.4
151.4
151.2
153.4
–
–
–
–
142.6
179.6
116.0
163.6
160.8
–
5d
5ee
150.8
177.2
–
–
–
–
1Jð13C–1HÞ in italics; N.D, not determinated; Compounds 1e–1d, 2a, 3a and 4a have been previously reported [9a].
a
1
1
1
d13C : N–CH3 ¼ 35.9, JCH ¼ 140:5; C–CH3 ¼ 10.2, JCH ¼ 129:9; N–C6H5: Ci ¼ 135.0, Co ¼ 124.6, JCH ¼ 163:4; Cm ¼ 129.4,
1JCH ¼ 162; Cp ¼ 127.1, 1JCH ¼ 162:3:
b
1
1
1
d13C : N–CH3 ¼ 35.9, JCH ¼ 140:8; C–CH3 ¼ 10.6, JCH ¼ 130:0; N–C6H5: Ci ¼ 134.9, Co ¼ 125.1, JCH ¼ 163:7; Cm ¼ 129.6,
1JCH ¼ 162:5; Cp ¼ 127.5, 1JCH ¼ 162:4:
c
1
1
1
d13C : N–CH3 ¼ 35.7, JCH ¼ 140:8; C–CH3 ¼ 10.2, JCH ¼ 130:2; N–C6H5: Ci ¼ 134.6, Co ¼ 124.8, JCH ¼ 163:7; Cm ¼ 129.4,
1JCH ¼ 162:6; Cp ¼ 127.3, 1JCH ¼ 161:9:
d
1
1
1
d13C : N–CH3 ¼ 35.6, JCH ¼ 140:9; C–CH3 ¼ 10.2, JCH ¼ 130:1; N–C6H5: Ci ¼ 134.5, Co ¼ 125.0, JCH ¼ 164:0; Cm ¼ 129.5,
1JCH ¼ 162:4; Cp ¼ 127.6, 1JCH ¼ 162:0:
e
1
1
1
d13C : N–CH3 ¼ 35.9, JCH ¼ 140:6; C–CH3 ¼ 10.5, JCH ¼ 129:8; N–C6H5: Ci ¼ 134.8, Co ¼ 124.6, JCH ¼ 163:3; Cm ¼ 129.4,
1JCH ¼ 162:3; Cp ¼ 127.1, 1JCH ¼ 162:4:

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R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
379
Table 2
1H, 13C and 15N NMR substituent chemical shifts effects (SCS) for
Table 3
15N NMR, chemical shift and two bond 1H–15N coupling constants
the aldimine group
for aldimines 1–5
NyC–H
Dd1H
Dd13
C
Dd15
N
Compound CyN
d15
R1
R2
R1
R2
0.14
R1
R2
0.0
R1
R2
10.3
N
nJNH d15
N
nJNH
d15
N
nJNH
2-Pyridyl
3-Pyridyl
4-Pyridyl
Pyrazolone
Furanyl
0.74
0.04
20.04
1.31
–
2.4
26.8
27.8
23.8
225.6
2
1a
1b
1c
1d
1e
255.66 4.1
260.94 4.6
261.79 4.8
258.02 5.2
279.97 3.7
2
–
–
–
–
–
–
–
–
–
–
–
0.08
0.03
–
1.6 23.5
2.8 22.8
6.6
14.6
–
293.98 11.7
265.54 21.9
278.42 20.9
2249.70a 4.8b
2198.80c 5.9d
23.4
2
2
–13.0
20.10
211.1
Reference compound: 1a, d1H ¼ 8:39; d13C ¼ 160:5; d15
2a
2b
2c
2d
2e
243.70 6.4
250.07 3.8
252.43 4.8
248.51 4.0
270.00 4.0
–
–
263.53 11.9
264.21 11.1
265.19 11.1
264.45 12.3
N ¼ 255:6:
291.88 11.5
265.77 21.1
276.46 20.7
2247.60a 5.2b 268.50 11.7
2199.80c 6.1d
strain and through space interaction with the lone pair
of the carbonyl group, as previously noted. A similar
effect was observed in the N-2-pyridyl derivatives
(1b, 2b, 3b, 4b and 5b). In these compounds the
pyridine nitrogen was oriented on the same side as the
aldimine hydrogen. The X-ray diffraction of the
pyrazolone derivatives confirmed this arrangement.
3a
3b
3c
3d
3e
246.92 3.7
254.96 4.5
255.87 4.5
251.80 4.4
273.97 4.4
–
–
267.84 21.1
267.37 21.3
268.27 20.7
266.86 21.4
293.70 12.0
266.43 21.5
276.04 21.6
2248.07a 4.5b 270.05 19.9
2199.10c 5.3d
4a
4b
4c
4d
4e
238.80 5.4
246.87 4.4
247.58 4.4
243.43 3.7
266.82 4.4
–
–
261.13 21.6
259.39 21.5
259.13 22.1
258.55 21.1
3.4. X-ray diffraction
293.14 12.2
264.95 21.6
275.89 21.1
2246.90a 6.1b 266.66 24.4
2199.30c 6.6dd
Adequate crystals for X-ray diffraction were
obtained for compounds 1e, 2e, 3e, 4e and 5e
(Table 6): the torsion angle between the pyrazolone
and the CyN double bond planes ranged from 1 to
7.58; the corresponding values for the aryl group was
4.4–138 (Table 7). The bond between the pyrazolone
and imine groups was s-trans, only the N–CH3 and
the N–C6H5 substituents of the pyrazolone moiety
showed deviation from the main plane due to the
steric effect (Fig. 1). The torsion angles obtained in
the pyrazolone derivatives differed considerably from
the results of the X-ray analysis [8] of compounds 1a,
2a, 3a and 4a which reported that the torsion angle
between the aryl group and the imine bond was
between 29 and 418. This effect cannot be attributed to
crystal packing because the same angles were
determined by 13C NMR in solution [9].
5a
5b
5c
5d
5e
267.01 4.1
273.43 3.3
273.23 3.7
269.21 4.1
289.21 3.7
–
–
–
–
–
–
–
–
–
–
–
–
295.62 13.7
265.50 22.6
277.54 20.9
2249.53a 4.8b
2199.08c 5.9d
a
b
c
d
N–CH3.
3J(15N–C–C–1H); N–CH3.
N–C6H5.
3J(15N–N–C–1H); N–C6H5.
ring (Table 7). No intermolecular interactions were
observed in the lattice (Fig. 2).
Contrary to a previous of X-ray diffraction report
[8] of compounds 2a, 3a and 4a, no disorder of the
pyridine ring was observed. The X-ray structure of
the 3-pyridine derivative 3e showed that, in this case,
the nitrogen of the aromatic group and the nitrogen
of the imine group are cis (Fig. 3, Table 8). The
2-pyridine derivative 1e had two rotamers in the unit
cell, one with the nitrogen syn to the imine bond and
the other one in an anti position (Fig. 4). The syn
The distance from the aldimine hydrogen to the
˚
pyrazolone carbonyl was 2.32 ^ 0.2 A (Table 7)
while that between the aldimine hydrogen or the
imine nitrogen with the aryl group was less than
˚
2.63 A, except for the structure of the furanyl
derivative 5e which exhibited a larger distance
˚
(2.818 A), due to the existence of a five member

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
380
Table 4
Three bond and long-range H–H coupling constants (Hz) in aldimines 1–5
Comp.
HCyN-3
R1
R2
2–3
2–4
3–4
3–5
4–5
4–6
5–6
20 –30
20 –40
30 –40
30 –50
40 –50
40 –60
50 –60
1a
1b
1c
1d
1e
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
4a
4b
4c
4d
4e
5a
5b
5c
5d
5e
0.3
0.5
0.4
0.4
0.4
0.4
0.3
0.3
0.3
0.3
–
8.0
–
1.2
–
7.4
4.9
–
1.8
1.9
–
7.4
7.3
4.8
–
1.2
1.1
1.5
–
8.0
7.8
8.1
5.0
–
7.9
7.5
7.7
7.9
7.9
–
1.6
1.4
1.4
1.7
1.7
–
7.4
7.2
7.4
7.0
7.5
4.8
4.8
4.9
4.8
4.8
–
1.3
1.6
1.5
1.4
1.7
1.7
1.7
1.7
1.7
1.7
–
7.4
7.2
7.4
7.0
7.5
7.5
7.6
7.6
7.5
7.6
4.8
4.8
4.9
4.9
4.8
–
1.6
1.4
1.4
1.7
1.7
1.2
1.2
1.2
1.2
1.2
1.7
1.7
1.7
1.7
1.7
–
7.9
7.5
7.7
7.9
7.9
7.9
7.9
8.0
7.9
7.9
7.8
7.8
8.0
8.0
8.0
5.0
5.0
4.9
5.0
5.0
–
–
0.3
–
5.0
–
–
1.0
–
–
–
–
–
8.1
–
1.2
–
7.6
4.8
–
1.7
2.0
–
7.6
7.5
4.8
–
1.2
1.1
1.5
–
8.1
7.8
7.9
5.0
–
–
–
–
0.3
–
–
–
5.0
–
–
1.4.
–
–
–
–
–
–
–
–
–
7.9
–
1.2
–
7.5
4.9
–
1.3
2.0
–
7.5
7.3
4.7
–
1.2
1.1
1.5
–
7.9
7.9
8.2
5.3
–
–
0.3
0.3
0.4
0.3
0.3
–
–
–
–
–
–
–
0.4
–
–
–
–
–
5.3
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
0.4
0.3
0.5
0.4
0.4
0.2
0.3
0.2
0.2
0.3
7.4
–
1.3
–
7.5
4.8
–
1.7
1.9
–
7.5
7.6
4.8
–
1.3
1.1
1.5
–
7.4
7.8
8.2
5.2
–
5.0
5.0
4.9
5.0
5.0
–
–
0.4
0.4
0.4
0.4
0.4
0.8
0.8
0.7
0.7
0.7
–
–
–
–
–
0.4
–
–
–
–
–
5.2
–
–
0.4
–
–
–
–
–
–
–
–
–
–
–
–
–
7.8
–
1.2
–
7.6
4.8
–
2.2
1.7
–
7.6
7.5
4.8
–
1.2
1.1
1.5
–
7.8
7.9
8.1
5.2
–
–
3.5
3.5
3.5
3.5
3.5
1.8
1.8
1.8
1.8
1.9
–
–
–
–
–
–
0.3
–
–
–
–
–
5.2
–
–
0.4
–
–
–
–
–
–
–
–
–
–
–
–
–
˚
rotamer showed a distance of 2.794 A between the
aromatic nitrogen to the imine nitrogen.
4. Conclusions
For the first time, the complete NMR analyses of
1
3.5. UV and IR analyses
the H, 13C and 15N chemical shift as well as the
coupling constants for a series 25 di-aryl-aldimines,
including the new derivatives 2c, 3d, 4b, 4c and 5c, is
reported.
Analyses of the ultraviolet spectra of imine
derivatives 1a–5e showed that heterocyclic azines,
such as the pyridyl group, were weak acceptors and
furan acted as a p-donor. Compounds containing a
NyC bond substituted by two pyridine groups showed
an hypsochromic shift with respect to phenyl
substituted ones. This effect was stronger in sub-
stances that had a phenyl group bonded to an imine
carbon. The derivatives that had an a-furanyl group
bonded to an iminic carbon showed a bathochromic
shift.
The interaction between the lone pair of the
pyrazolone carbonyl group or nitrogen of N-2-
pyridine with the aldimine hydrogen was evidenced
1
by an increase in the JCH value (3.2 ^ 0.8 and
7.3 ^ 0.4 Hz, respectively). In these compounds, the
aldimine hydrogen is shifted to higher frequency, in
the 1H NMR spectra (Dd1H 1.3 and 0.7 respectively).
The UV of these compounds showed a blue UV shift
and a planar arrangement in the solid state, established
by X-ray diffraction studies of aldimines 1e, 2e, 3e, 4e
and 5e. The distance between the aldimine hydrogen
and the oxygen of the carbonyl group was shorter than
The infrared spectra showed the characteristic
stretching bands for the conjugated imine bond, all of
which were in the same region, thus precluding
unequivocal assignment.
˚
the sum of the Van der Walls radii (2.32 ^ 0.02 A).

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
381
Table 5
1H NMR, chemical shift ðdÞ for aldimines 1–5
Comp.
HCyN
R1
R2
20
2
3
4
5
6
30
7.42
40
7.42
50
60
1a
1b
1c
8.39
9.14
8.41
8.31
9.76
8.60
9.22
8.62
8.52
9.78
8.46
9.22
8.53
8.45
9.78
8.40
9.15
8.47
8.40
9.71
8.27
9.11
8.29
8.23
9.63
7.19
–
7.35
7.20
7.35
7.19
7.87
7.98
7.89
7.87
7.86
–
7.42
7.44
7.45
7.44
7.41
7.72
7.75
7.84
7.85
7.70
7.38
7.40
7.44
7.45
7.34
8.72
8.75
8.76
8.78
8.66
7.59
7.65
7.64
7.66
7.56
7.87
7.98
7.89
7.87
7.86
8.17
8.20
8.21
8.18
8.03
8.26
8.33
8.31
8.29
8.17
7.74
7.79
7.76
7.76
7.69
–
8.47
–
7.12
8.46
–
7.69
7.28
8.53
–
7.31
7.48
6.98
–
7.44
7.45
7.44
7.41
8.67
8.75
8.74
8.74
8.64
–
7.46
7.50
7.48
7.39
7.28
7.36
7.41
7.43
7.23
8.68
8.71
8.73
8.85
8.60
–
8.49
6.98
–
1d
1ea
2a
2b
2c
8.54
–
–
7.28
–
7.38
8.52
–
7.24
7.19
8.53
–
7.38
7.79
7.36
8.61
–
7.28
7.38
7.60
7.08
–
–
8.58
7.08
–
–
2d
2eb
3a
3b
3c
8.61
–
–
–
–
7.22
–
7.39
8.50
–
7.25
7.19
8.51
–
7.39
7.75
7.36
8.60
–
7.22
7.35
7.57
7.05
–
9.00
9.10
9.00
9.03
9.01
7.74
7.79
7.76
7.76
7.69
–
–
8.52
7.05
–
–
3d
3ec
4a
4b
4c
8.60
–
–
–
–
7.24
–
7.41
8.49
–
7.28
7.19
8.52
–
7.41
7.74
7.34
8.60
–
7.24
7.36
7.56
7.06
–
8.72
8.75
8.76
8.78
8.66
6.94
7.06
7.02
7.06
6.78
–
8.53
7.06
–
–
4d
4ed
5a
5b
5c
8.60
–
–
–
–
7.23
–
7.37
8.46
–
7.22
7.16
8.46
–
7.37
7.74
7.29
8.57
–
7.23
7.41
7.53
7.06
–
6.53
6.57
6.56
6.59
6.50
–
–
8.52
7.06
–
–
–
5d
5ee
8.57
–
–
–
–
–
–
a
d1H : N–CH3 ¼ 3.15, C–CH3 ¼ 2.49, N–C6H5: Ho ¼ 7.41, Hm ¼ 7.48, Hp ¼ 7.32.
d1H : N–CH3 ¼ 3.13, C–CH3 ¼ 2.46, N–C6H5: Ho ¼ 7.36, Hm ¼ 7.44, Hp ¼ 7.29.
d1H : N–CH3 ¼ 3.19, C–CH3 ¼ 2.50, N–C6H5: Ho ¼ 7.40, Hm ¼ 7.49, Hp ¼ 7.36.
d1H : N–CH3 ¼ 3.22, C–CH3 ¼ 2.51, N–C6H5: Ho ¼ 7.39, Hm ¼ 7.50, Hp ¼ 7.36.
d1H : N–CH3 ¼ 3.15, C–CH3 ¼ 2.48, N–C6H5: Ho ¼ 7.40, Hm ¼ 7.48, Hp ¼ 7.32.
b
c
d
e
These observations agree with previous reports [14]
Chemical shifts were referenced [15] to internal
(CH3)4Si (d1H ¼ 0; d13Cy0) and neat CH3NO2
(d15N for J15N ¼ 10.136767 MHz). 1H NMR spectra
were recorded at 300 MHz. The 13C NMR spectra
were determined at 75.47 MHz with [16] and without
[17] decoupling using the nuclear Overhauser
enhancement method. 15N NMR spectra were
obtained at 30.38 MHz by INEPT methods [18]
HMQC 1H–15N spectra were obtained on a Jeol
Eclipse þ400 spectrometer at 399.79 and 40.51 MHz
respectively using the pulse field gradient sequence
[19] with a 5 mm reverse detection multinuclear
probe.
concerning hydrogen bond interactions.
The 15N chemical shift showed additive substituent
effects for the imine nitrogen and negligible effects in
the heterocycle. Similar observations were derived
1
from careful evaluation of the 13C and H data.
5. Experimental part
5.1. Instruments
1H, 13C and 15N NMR spectra were recorded with a
Bruker 300 Avance spectrometer equipped with a
5 mm multinuclear probe using CDCl3 solution
(0.9 mmol of the compound per 0.4 ml of solvent).
Melting points were measured on a Mel-Temp 3.0
(laboratory device inc. USA) and are given without
correction. Elemental analyses were performed on

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
382
Table 6
Crystal data for compounds 1e, 2e, 3e, 4e, 5e
Compounds
1e
2e
3e
4e
5e
Empirical formula
Formula weight
Crystal size (nm)
Crystal color
C18H17N3O
291.36
C17H16N4O
292.34
C17H16N4O
292.34
C17H16N4O
292.34
C16H15N3O2
281.32
0.15 £ 0.17 £ 0.1
Yellow
0.25 £ 0.2 £ 0.17
Yellow
0.5 £ 0.57 £ 0.15
Yellow
0.62 £ 0.17 £ 0.05
Yellow
0.4 £ 0.4 £ 0.1
Orange
Crystal system
Space group
Monoclinic
P21=c
Monoclinic
P21=a
Monoclinic
P21=a
Monoclinic
P21=a
Monoclinic
P21=c
˚
Unit cell dimensions (A)
a ¼ 12:9980ð3Þ
b ¼ 6:8704ð2Þ
c ¼ 17:1969ð1Þ
b ¼ 91:027ð7Þ
1535.5(8)
4
a ¼ 13:8069ð4Þ
b ¼ 10:0367ð3Þ
c ¼ 23:1931ð6Þ
b ¼ 105:343ð2Þ
3099.45(15)
8
a ¼ 6:9907ð2Þ
b ¼ 25:1699ð6Þ
c ¼ 8:6300ð2Þ
b ¼ 97:364ð1Þ
1505.97(7)
4
a ¼ 7:0044ð2Þ
b ¼ 24:9126ð6Þ
c ¼ 8:6854ð3Þ
b ¼ 98:034ð1Þ
1500.71(8)
4
a ¼ 11:1637ð1Þ
b ¼ 9:9139ð1Þ
c ¼ 13:6443ð1Þ
b ¼ 106:4050ð5Þ
1448.62(8)
4
3
˚
Volume (A)
Z
Density (calculated mg/m3)
Absorption coefficient (cm21
Fð000Þ
1.26
1.253
1.289
1.294
1.28
)
0.75
0.82
0.84
0.84
0.82
616
1232
616
616
592
Temperature (K)
u range for collection(8)
Index range
293(2)
293(2)
293(2)
293(2)
293(2)
2.16–20
212 # h # 12
0 # k # 6
0 # l # 16
1659
3.40–26.36
217 # h # 17
212 # k # 12
228 # l # 28
10691
3.40–27.45
29 # h # 9
230 # k # 32
211 # l # 11
6023
3.41–27.88
29 # h # 9
232 # k # 9
211 # l # 11
6042
2.23–25
212 # h # 13
211 # k # 0
216 # l # 0
2706
Reflections collected
Independent reflection
Observed reflection
CCDC
1430
6280
3358
3517
2494
488
3036
1887
1733
1679
194856
194857
194858
194859
194855
CCDC, Cambridge Crystallographic Data Center. Radiation and wavelength: Mo Ka, l ¼ 0:71073:
a Thermo Finnigan Flash 1112. Mass spectra were
obtained by electronic ionization at 70 eV in a
Hewlett Packard HP-5989 spectrometer. UV spectra
were recorded on a Perkin–Elmer lambda 12 using
CH2Cl2 as solvent. Infrared spectra were determined
in CH2Cl2 using a Perkin–Elmer 16F PC FT-IR
spectrometer.
X-ray monocrystal diffraction analyses for
compounds 1e and 5e, collection, structure resol-
ution and refinement were performed using an
Table 7
Selected torsion angles, distances and angles
Torsion angle (8)
1e
2e
3e
4e
5e
C12–N3–C2–C3
R2–C12–N3
2178.9
2174.9
2177.9
258.9
2172.5
2172.2
176.7
45.5
175.5
2174.8
174.8
50.4
179.9
179.7
177.9
2166.7
2176.0
252.7
26.2
2171.1
2175.9
250.7
25.1
2175.6
2176.1
252.8
26.4
C3–C2–C1–O1
C5–N2–N1–C6
C3–C2–N2–N1
210.0
6.6
5.3
˚
Contact distance (A)
H12–O1
2.466
2.632
2.443
2.310
2.555
–
2.320
–
2.355
2.550
2.417
2.310
2.574
2.399
2.289
–
Aryl-H–N3
Aryl-H–H12
Contact angle (8)
C12–H12–O1
Aryl-H–N3
2.369
2.818
123.03
91.36
126.31
97.74
126.56
–
123.81
98.40
126.25
96.87
130.27
-

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
383
Fig. 1. X-ray molecular structure of aldimines (a) 4e and (b) 5e.
Enraf-Nonius CAD4 diffractometer. For compounds
5.3. Preparation of compounds
2e, 3e and 4e, the collection was preformed with a
Siemens P4 instrument equipped with a CCD area
detector. The WinGX software [20] was used for
structure solution, refinement and data output. All
hydrogen atoms in structures 2e, 3e, 4e and 5e
were found in the difference Fourier map. Crystal-
lographic data for the structures reported in this
paper have been deposited with the Cambridge
Crystallographic Data as supplementary material.
Copies of the data can be obtained free applying
to: CCDC, 12 Union Road, Cambridge, CB2 IEZ,
UK; fax: þ44-1223-336033 e-mail: deposit@ccdc.-
cam.ac.uk Cambridge registered numbers are:
CCDC 194855 to 194859.
The aldimines were prepared by the standard
method, azeotropic distillation of the amine and the
corresponding aldehyde in benzene (compounds 1a,
5a–5c), toluene (compounds 1b, 1c, 2a–2d, 3a–3d,
4a–4d and 5d), m-xylene (compound 1d) or methy-
lenechloride (compounds 1e, 2e, 3e, 4e, 5e) with p-
toluenesulphonic acid as catalyst. The solvent was
evaporated under vacuum. Imine–pyridine deriva-
tives (1b–1d, 2b–2d, 3b–3d, 4b–4d and 5b–5d)
were washed thoroughly with water. The pyrazolone
derivatives 1e, 2e, 3e, 4e and 5e were recrystallized
from CH2Cl2/hexane and compounds 2c, 3d, 4c, 5c
and 5d were distilled under vacuum.
The spectral and physical properties of 1a [21],
1b [22], 1c [23], 1d [21], 1e [24], 2a [21], 2b [25],
2e [26], 3a [21], 3b [21], 3e [25], 4a [21], 4d [27],
4e [25], 5a [28], 5b [29] and 5e [30] were in good
agreement with previous reports.
5.2. Reagents
Aldehydes and amines (Aldrich) were used as
received except for aniline and furaldehyde that were
distilled prior to use.
N-(phenylmethylene)benzenamine, 1a. m.p.
49–51 8C. EI-MS: m=zð%Þ 182(13)[Mþ þ 1],

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
384
Fig. 2. Crystal packing for compound 1e.
Fig. 3. X-ray diffraction for compound 3e.

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
385
Table 8
Select bond distances and bond angles
1a
2e
3e
4e
5e
˚
Distances (A)
C13–C12
C12–N3
N3–C2
C2–C3
C2 C1
1.49(2)
1.27(2)
1.40(1)
1.36(2)
1.43(2)
1.23(2)
1.36(1)
1.48(2)
1.46(2)
1.40(1)
1.42(1)
1.45(1)
1.34(2)
1.42(2)
1.33(2)
1.33(2)
1.42(2)
1.39(2)
1.468(4)
1.276(3)
1.395(3)
1.369(3)
1.435(4)
1.231(3)
1.362(3)
1.483(4)
1.451(3)
1.388(3)
1.400(3)
1.428(3)
1.370(4)
1.382(4)
1.372(5)
1.361(6)
1.378(5)
1.379(4)
1.468(4)
1.280(3)
1.395(3)
1.372(3)
1.437(4)
1.236(3)
1.356(3)
1.482(4)
1.456(3)
1.396(3)
1.399(3)
1.430(3)
1.380(4)
1.382(4)
1.366(5)
1.378(5)
1.381(4)
1.373(4)
1.464(3)
1.279(2)
1.392(2)
1.369(2)
1.432(2)
1.235(2)
1.353(2)
1.485(3)
1.460(3)
1.404(2)
1.4052(19)
1.424(2)
1.378(3)
1.376(3)
1.365(4)
1.362(4)
1.391(4)
1.375(3)
1.466(3)
1.285(2)
1.397(2)
1.372(3)
1.436(3)
1.234(2)
1.352(3)
1.481(3)
1.456(2)
1.402(2)
1.403(2)
1.424(3)
1.379(3)
1.387(4)
1.372(5)
1.377(5)
1.374(4)
1.377(3)
1.425(4)
1.283(3)
1.390(3)
1.372(3)
1.435(4)
1.236(3)
1.357(3)
1.483(4)
1.456(4)
1.392(3)
1.400(3)
1.427(3)
1.387(4)
1.382(4)
1.365(5)
1.378(5)
1.375(5)
1.376(4)
C1–O1
C3–N2
C3–C4
N2–C5
C1–N1
N1–N2
N1–C6
C6–C7
C7–C8
C8–C9
C9–C10
C10–C11
C11–C6
Angles (8)
C13–C12–N3
C12–N3–C2
N3–C2–C1
N3–C2–C3
O1–C1–C2
O1–C1–N1
C1–C2–C3
C2–C3–C4
C2–C3–N2
C4–C3–N2
C3–N2–C5
C3–N2–N1
N1–N2–C5
C1–N1–N2
C1–N1–C6
N2–N1–C6
N1–C6–C7
N1–C6–C11
C6–C7–C8
C7–C8–C9
C8–C9–C10
C9–C10–C11
C10–C11–C6
C11–C6–C7
121.3(15)
120.5(12)
130.1(13)
121.2(12)
131.5(13)
123.9(13)
108.0(11)
127.9(14)
111.4(13)
120.7(15)
126.1(13)
105.0(12)
117.6(12)
109.7(10)
120.8(11)
117.8(11)
122.9(13)
115.4(12)
118.3(17)
120.7(18)
121.3(19)
120.7(18)
117.4(16)
121.7(14)
120.6(3)
121.3(2)
129.3(2)
122.5(2)
131.5(3)
123.7(3)
108.2(2)
129.3(3)
109.7(2)
121.0(3)
124.9(2)
106.9(2)
118.6(2)
109.7(2)
125.1(2)
121.0(2)
121.8(3)
117.8(3)
119.3(4)
120.7(4)
119.5(4)
120.8(4)
119.3(4)
120.4(3)
122.3(3)
120.0(2)
128.9(2)
123.0(2)
131.8(2)
123.1(2)
108.0(2)
128.6(2)
109.9(2)
121.5(2)
125.0(2)
107.55(19)
118.3(2)
109.2(2)
124.5(2)
120.5(2)
120.7(3)
118.5(2)
119.0(3)
120.5(3)
120.3(3)
119.8(4)
119.6(3)
120.8(3)
120.90(18)
120.99(16)
129.17(15)
122.67(15)
132.12(17)
122.60(16)
107.99(15)
128.67(19)
110.20(15)
121.12(17)
126.37(17)
107.50(13)
118.79(17)
108.59(13)
122.99(14)
119.41(14)
120.80(17)
118.51(19)
119.5(2)
120.9(2)
122.0(3)
120.9(2)
129.3(2)
122.6(2)
131.3(3)
123.5(3)
107.9(2)
128.6(2)
109.8(2)
121.6(2)
123.1(2)
107.4(2)
118.0(2)
109.1(2)
125.2(2)
119.8(2)
120.9(3)
118.4(3)
118.7(3)
120.9(4)
119.9(3)
120.3(4)
119.5(4)
120.6(3)
120.43(18)
129.00(17)
122.58(18)
132.17(18)
122.97(18)
108.25(17)
129.0(2)
109.87(17)
121.07(19)
126.91(17)
107.67(15)
119.40(16)
108.95(15)
122.03(16)
119.96(16)
120.77(19)
118.3(2)
118.9(3)
120.6(3)
120.3(3)
120.3(3)
119.8(3)
120.5(3)
120.5(3)
118.8(3)
120.7(2)
119.5(3)
120.9(2)

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
386
Fig. 4. X-ray molecular structure of compound 2e, showing two independent molecules in the unit cell.
181(94)[Mþ], 180(100), 104(12), 77(61), 51(31). IR
N-(2-pyridinemethylene)-2-pyridinamine, 2b. EI-
MS: m=zð%Þ 184(9)[Mþ þ 1], 183(48)[Mþ],
182(100), 156(33), 155(27), 105(25), 79(90), 78(64),
52(42), 51(46). IR nmax (cm21): 1626, 1592, 1570,
1472, 1438, 1364, 1270(t). UV lmax=nm ð1Þ 247
(5862), 289 (4342).
n
263 (16537), 235 (10647), 307 (7929).
max (cm21): 1694, 1628, 1592, 1580. UV lmax=nm ð1Þ
N-(phenylmethylene)-2-pyridinamine, 1b. m.p.
102–106 8C. EI-MS: m=zð%Þ 183(1)[Mþ þ 1],
182(11)[Mþ], 181(27), 79(100), 52(28), 51(30). IR
n
max (cm21): 3020, 1704, 1676, 1622, 1586, 1562. UV
N-(2-pyridinemethylene)-3-pyridinamina, 2c. b.p.
105–108 8C/0.003 mmHg. Yield 85%. Anal. Calcd.
for C11H9N3: C ¼ 72.11%, H ¼ 4.95%, N ¼ 22.93%.
Found: C ¼ 71.92, H ¼ 5.04, N ¼ 23.11. EI-MS:
m=zð%Þ 184(6)[Mþ þ 1], 183(23)[Mþ], 182(100),
155(19), 78(21), 51(24). IR nmax (cm21): 1630,
l
max=nm ð1Þ 251 (11662), 298 (10387).
N-(phenylmethylene)-3-pyridinamine, 1c. EI-MS:
m=zð%Þ 183(13)[Mþ þ 1], 182(100)[Mþ], 181(99),
105(8), 89(16), 78(73), 51(42). IR nmax (cm21): 3050,
1628, 1578. UV lmax=nm ð1Þ 271 (14057), 259
(13276).
1588, 1570, 1474, 1438, 1416, 1272(d). UV lmax
nm ð1Þ 248 (15115), 282 (13232).
=
N-(phenylmethylene)-4-pyridinamine, 1d. EI-MS:
m=zð%Þ 183(14)[Mþ þ 1], 182(100)[Mþ], 181(85),
105(7), 89(9), 78(75), 51(63). IR nmax (cm21): 1706,
1630, 1598, 1584. UV lmax=nm ð1Þ 263 (12553).
N-(phenylmethylene)-1,5-dimethyl-2-phenyl-1,2-
dihydro-pyrazol-3-one, 1e. m.p. 175–177 8C. EI-MS:
m=zð%Þ 292(8)[Mþ þ 1], 291(37)[Mþ], 199(10),
188(11), 121(17), 77(13), 56(100), 28(10). IR nmax
(cm21): 3048, 1704, 1654, 1584. UV lmax=nm ðeÞ 335
(5982), 241 (5050), 259 (4817).
N-(2-pyridinemethylene)-4-pyridinamina, 2d. EI-
MS: m=zð%Þ 184(5)[Mþ þ 1], 183(40)[Mþ],
182(100), 155(18), 79(97), 78(37), 52(34), 51(42).
IR nmax (cm21): 1636, 1270, 910. UV lmax=nm ð1Þ 248
(6805).
N-(2-pyridinemethylene)-1,5-dimethyl-2-phenyl-
1,2-dihydro-pyrazol-3-one, 2e. m.p. 161–165 8C. EI-
MS: m=zð%Þ 293(6)[Mþ þ 1], 292(27)[Mþ], 200(21),
172(24), 121(18), 77(11), 56(100). IR nmax (cm21):
1658, 1594, 1566, 1498, 1468, 1456, 1424,1412,
1270(d). UV lmax=nm ð1Þ 343 (18710), 258 (16371),
246 (15202).
N-(2-pyridinemethylene)benzenamine, 2a. EI-MS:
m=zð%Þ 183(7)[Mþ þ 1], 182(52)[Mþ], 181(100),
155(28), 154(29), 79(22), 77(43), 51(36). IR nmax
(cm21): 1630, 1592, 1568, 1498,1486, 1468, 1436
1266. UV lmax=nm ð1Þ 236 (6977), 282 (4478), 318
(4134).
N-(3-pyridinemethylene)benzenamine, 3a. EI-MS:
m/z(%) 183(16)[Mþ þ 1], 182(100)[Mþ], 181(77),
104(13), 77(53), 51(33). IR nmax (cm21): 1706, 1628,

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
387
1590, 1572, 1486, 1452, 1420 1266(d). UV lmax=nm
ð1Þ 238 (5597), 245 (4556), 320 (2777).
H ¼ 4.95%, N ¼ 22.93%. Found: C ¼ 72.11,
EI-MS:
184(17)[Mþ þ 1], 183(100)[Mþ], 182(43), 105(24),
79(25), 78(50), 51(32). IR nmax (cm21): 1714, 1630,
1598, 1560, 1476, 1416 1268 (d). UV lmax=nm ð1Þ 234
(12611), 273 (9399).
H ¼ 4.96,
N ¼ 22.58.
m=zð%Þ
N-(3-pyridinemethylene)-2-pyridinamine, 3b. m.p.
64–68 8C. Yield 64%. Anal. Calcd. for C11H9N3:
C ¼ 72.11%, H ¼ 4.95%, N ¼ 22.93%. Found:
C ¼ 72.24, H ¼ 5.17, N ¼ 22.90. EI-MS: m=zð%Þ
184(3)[Mþ þ 1], 183(17)[Mþ], 182(100), 155(13),
105(6), 79(46), 78(23), 52(23), 51(26). IR nmax
(cm21): 1624, 1588, 1562, 1462, 1434, 1266(d). UV
N-(4-pyridinemethylene)-4-pyridinamine, 4d. m.p.
77–78.8 8C. EI-MS: m=zð%Þ 184(16)[Mþ þ 1],
183(100)[Mþ], 182(38), 105(25), 78(46), 51(48). IR
nmax (cm21): 1636, 1598, 1566, 1506, 1486, 1458,
1414 1270 (d). UV lmax=nm ð1Þ 244 (11909).
N-(4-pyridinemethylene)-1,5-dimethyl-2-phenyl-
1,2-dihydro-pyrazol-3-one, 4e. m.p. 236.9–239 8C.
EI-MS: m=zð%Þ 293(8)[Mþ þ 1], 292(41)[Mþ],
200(13), 188(19), 121(39), 77(14), 56(100). IR nmax
l
max=nm ð1Þ 240 (15153), 270 (6297), 290 (6101).
N-(3-pyridinemethylene)-3-pyridinamine, 3c. m.p.
20–25 8C. Yield 73%. Anal. Calcd. for C11H9N3:
C ¼ 72.11%, H ¼ 4.95%, N ¼ 22.93%. Found:
C ¼ 72.11, H ¼ 5.23, N ¼ 22.76. EI-MS: m=zð%Þ
184(16)[Mþ þ 1], 183(100)[Mþ], 182(54), 105(12),
78(40), 51(24). IR nmax (cm21): 1706, 1630, 1590,
1572, 1476, 1420 1264(d). UV lmax=nm ð1Þ 246
(10626), 278 (10626).
(cm21): 1660, 1572, 1498, 1414 1268 (d). UV lmax
nm ð1Þ 349 (5962), 241 (5193), 255 (5193).
=
N-(2-furanylmethylene)-benzenamine, 5a. m.p.
57–59 8C. EI-MS: m=zð%Þ 172(13)[Mþ þ 1],
171(100)[Mþ], 170(62), 142(30), 115(27), 77(65),
51(42), 38(24). IR nmax (cm21): 3052, 1634, 1590,
1476. UV (CH2Cl2) lmax=nm ð1Þ 286 (17365), 316
(12718), 229 (8560), 237 (6603).
N-(3-pyridinemethylene)-4-pyridinamine, 3d. b.p.
74–77 8C/0.007 mmHg. m.p. 20–25 8C. Yield 53%.
Anal. Calcd. for C11H9N3: C ¼ 72.11%, H ¼ 4.95%,
N ¼ 22.93%. Found: C ¼ 72.39, H ¼ 5.21,
N ¼ 23.13. EI-MS: m=zð%Þ 184(23)[Mþ þ 1],
183(100)[Mþ], 182(59), 105(12), 78(32), 51(33). IR
N-(2-furanylmethylene)-2-pyridinamine, 5b. EI-
MS: m=zð%Þ 173(5)[Mþ þ 1], 172(37)[Mþ],
171(22), 144(48), 118(100), 79(76), 52(56), 51(54),
39(35). IR nmax (cm21): 3026, 1696, 1624, 1614,
1594, 1584. UV lmax=nm ð1Þ 282 (18946), 320
(17793), 247(11479).
n
max (cm21):1634, 1586,1574, 1558, 1506, 1488, 1422
1268(d). UV lmax=nm ð1Þ 250 (14886), 272 (11832).
N-(3-pyridinemethylene)-1,5-dimethyl-2-phenyl-
1,2-dihydro-pyrazol-3-one, 3e. m.p. 201 to 205 8C.
EI-MS: m=zð%Þ 293(7)[Mþ þ 1], 292(29)[Mþ],
200(9), 188(13), 121(25), 77(15), 56(100). IR nmax
(cm21): 1654, 1594, 1498, 1456, 1410 1266(d). UV
N-(2-furanylmethylene)-3-pyridinamine, 5c. b.p.
113–117 8C/0.01 mmHg. Yield 93%. Anal. Calcd. for
C10H8N2O: C ¼ 69.79%, H ¼ 4.68%, N ¼ 16.27%
O ¼ 9.29%. Found: C ¼ 69.48, H ¼ 4.69, N ¼ 16.43.
EI-MS: m=zð%Þ 173(12)[Mþ þ 1], 172(100)[Mþ],
171(29), 118(30), 78(44), 52(27), 51(46), 39(28). IR
l
max=nm ð1Þ 341 (15226), 254 (14081).
N-(4-pyridinemethylene)benzenamine, 4a. EI-MS:
m=zð%Þ 183(15)[Mþ þ 1], 182(100)[Mþ], 181(46),
104(30), 77(60), 51(37). IR nmax (cm21): 1628, 1598,
1558, 1486, 1452, 1410 1268 (d). UV lmax=nm ð1Þ 231
(3796), 257 (2603), 322 (1616).
n
max (cm21):3050,1676,1634,1630,1570,1470,1416.
UV lmax=nm ð1Þ 304 (10801), 232 (3240).
N-(4-pyridinemethylene)-2-pyridinamine, 4b. m.p.
40–44 8C. Yield 73%. Anal. Calcd. for C11H9N3:
C ¼ 72.11%, H ¼ 4.95%, N ¼ 22.93%. Found:
C ¼ 71.92, H ¼ 5.07, N ¼ 22.65. EI-MS: m=zð%Þ
184(8)[Mþ þ 1], 183(41)[Mþ], 182(100), 155(17),
79(87), 78(35), 52(30), 51(41). IR nmax (cm21): 1624,
1598, 1564, 1554, 1462, 1434, 1412 1270 (d). UV
N-(2-furanylmethylene)-4-pyridinamine, 5d. b.p.
84–87 8C/0.003 mmHg. m.p. 76.5 s 78.1 8C Anal.
Calcd. for C10H8N2O: C ¼ 69.79%, H ¼ 4.68%,
N ¼ 16.27% O ¼ 9.29%. Found: C ¼ 69.48,
H ¼ 4.69,
N ¼ 16.43.
EI-MS:
m=zð%Þ
173(11)[Mþ þ 1], 172(100)[Mþ], 171(31), 143(44),
78(46), 51(66), 39(34). IR nmax (cm21): 3038, 1696,
1680, 1624. UV lmax=nm ð1Þ 293 (18571).
l
max=nm ð1Þ 234 (10289), 241 (9747), 294 (4513).
N-(4-pyridinemethylene)-3-pyridinamine, 4c. b.p.
105–108 8C/0.003 mmHg, m.p. 48–52 8C. Yield
93%. Anal. Calcd. for C11H9N3: C ¼ 72.11%,
N-(2-furanylmethylene)-1,5-dimethyl-2-phenyl-
1,2-dihydro-pyrazol-3-one, 5e. EI-MS: m=zð%Þ
282(6)[Mþ þ 1], 281(33)[Mþ], 172(10), 121(8),

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
388
77(8), 56(100), 51(11), 28(9). IR nmax (cm21): 3054,
1656, 1596, 1552. UV lmax=nm ð1Þ 339 (18664), 257
(9467).
[9] (a) E. Denecke, K. Mu¨ller, T. Bluhm, Org. Magn. Reson. 18
(1982) 68.
(b) H.P. Erb, T. Bluhm, Org. Magn. Reson. 14 (1980) 285.
´ ´
(c) J.M. Ruxer, A. Solladie-Cavallo, G. Solladie, D. Olliero,
Org. Magn. Reson. 10 (1977) 105.
(d) P. Audoye, R.C. Coumes, A. Gaset, J.P. Gorrichon, Can.
J. Chem. 60 (1982) 1148.
Acknowledgements
[10] Z.H. Yu, X.Q. Peng, J. Phys. Chem. A 105 (2001) 8541.
[11] NUTS NMR utility transform software, www.acornnmr.com
[12] (a) V.M.S. Gil, W. von Philipsborn, Magn. Reson. Chem. 27
(1989) 409.
We thank Dr Hugo Tlahuext for X-ray structure of
compound 1e and 5e. R.M-G is grateful with
CONACyT and PROMEP for the scholarships and
Professor R. Santillan for critical discussions.
(b) A. Ariza-Castolo, M.A. Paz-Sandoval, R. Contreras,
Magn. Reson. Chem. 30 (1992) 520.
[13] (a) D.R. Boyd, M.E. Stubbs, N.J. Thompson, H.J.C. Yeh,
D.M.Jerina,R.E.Wasylishen,Org.Magn.Reson.14(1980)528.
(b) G.W. Buchnan, B.A. Dawson, Org. Magn. Reson. 13 (1980)
293.
References
[1] R.W. Layer, Chem. Rev. 63 (1964) 489.
[2] (a) T. Chary, M. Mohana, A. Krishnamurty, Indian J. Chem.
Sect. B 34B (1995) 65.
[14] (a) R.H. Contreras, J.E. Peralta, C.G. Giribet, M.C. Ruiz de
´
Azua, J.C. Facelli, Ann. Report. NMR Spect. 41 (2000) 55.
(b) A.J. Stone, Chem. Phys. Lett. 211 (1993) 101.
(b) M. Jean-Luc, M. Schmitt, V. Collot, B. Jean-Jacques,
Heterocycles 45 (1997) 897.
(c) U. Koch, P.L.A. Popelier, J. Phys. Chem. 99 (1995) 9474.
´
(d) C.G. Giribet, C.V. Vizioli, M.C. Ruiz de Azua, J.J.
(c) V. Derdau, V. Snieckus, J. Org. Chem. 66 (2001) 1992.
(d) D.W. Nelson, J. Owens, D. Hiraldo, J. Org. Chem. 66
(2001) 2572.
Contreras, J.J. Dannenberg, A. Masumov, J. Chem. Soc.
Faraday Trans. 92 (1996) 3029.
[15] R.K. Harris, E.D. Becker, S.M. Cabral de Menezes,
R. Goodfellow, P. Granger, Magn. Reson. Chem. 40 (2002)
489.
(e) S. Schunk, D. Enders, Org. Lett. 2 (2000) 907.
(f) Y.K. Popandova, J. Chem. Res. Synop. 1 (1998) 57.
(g) A.R. Katritzky, L. Zhang, J. Yao, O.V. Denisko, J. Org.
Chem. 65 (2000) 8074.
[16] H.O. Kalinowski, S. Berger, S. Braun, Carbon-13 NMR
Spectroscopy, Wiley, Chichester, 1991.
(h) P.K. Choudhury, F. Foubelo, M. Yus, J. Org. Chem. 64
(1999) 3376.
[17] O.A. Gansow, W. Schittenhelm, J. Am. Chem. Soc. 93 (1971)
4294.
(i) J.M. Mohan, B.S. Uphade, V.R. Houdhary, T. Ravindra-
nathan, A. Sudalai, Chem. Commun. (1997) 1429.
(j) T. Tsukinoki, Y. Mitoma, S. Nagashima, T. Kawaji, I.
Hashimoto, M. Tashiro, Tetrahedron Lett. 39 (1998) 8873.
[3] (a) M. Michalik, T. Freier, K. Zahn,, K. Peseke, Magn. Reson.
Chem. 35 (1997) 859.
[18] (a) G.A.Morris,R.Freeman,J.Am.Chem.Soc.101(1979)760.
(b) D.P. Burum, R.R. Ernst, J. Magn. Reson. 39 (1980) 163.
(c) O.W. Sørensen, R.R. Ernst, J. Magn. Reson. 51 (1983) 477.
[19] (a) R.E. Hurd, B.K. John, J. Magn. Reson. 91 (1991) 648.
(b) J. Ruiz-Cabello, G.W. Vuister, C.T.W. Moonen, P. van
Gelderen, J.S. Cohen, P.C.M. van Zijl, J. Magn. Reson. 100
(1992) 282.
´
´
(b) M.S. Morales-Rıos, M. Garcıa-Velgara, H. Cervantes-
Cuevas, C. Alvarez-Cisneros, P. Joseph-Nathan, Magn.
Reson. Chem. 38 (2000) 172.
(c) W. Willker, D. Leibfritz, R. Kerssebaum, W. Bermel,
Magn. Reson. Chem. 31 (1993) 287.
(c) T. Freier, M. Michalik, K. Peseke, H. Reinke, J. Chem.
Soc. Perkin Trans. 2 (1999) 1265.
[20] L.J. Farrugia, J. Appl. Cryst. 32 (1999) 837.
[21] (a) R. Akaba, H. Sakuragi, K. Tokumaru, Bull. Chem. Soc.
Jpn 58 (1985) 301.
[4] (a) R.A. Rijkenberg, D. Bebelaar, W.J. Buma, J.W. Hofstraat,
J. Phys. Chem. A (2002).
(b) R. Akaba, K. Tokumaru, T. Kobayashi, Bull. Chem. Soc.
Jpn 53 (1993) 1980.
(b) S. Bradamante, A. Facchetti, G.A. Pagani, J. Phys. Org.
Chem. 10 (1997) 514.
´
´
(c) P. Nongkunsarn, C.A. Ramsden, Tetrahedron 53 (1997)
3805.
[5] M.S. Morales-Rıos, O.R. Suarez-Castillo, C. Alvarez-Cis-
neros, P. Joseph-Nathan, Can. J. Chem. 77 (1999) 130.
[6] G. Fischer, W.D. Rudorf, E. Kleinpeter, Magn. Reson. Chem.
29 (1991) 212.
(d) C.S. Barnes, E.J. Halbert, R.J. Goldsack, J.G. Wilson,
Aust. J. Chem. 26 (1973) 1031.
(e) P. Skrabal, J. Steiger, H. Zollinger, Helv. Chim. Acta 58
(1975) 800.
[7] (a) A. Streitwieser, C.H. Heathcock, Introduction to Organic
Chemistry, Macmillan Publishing Company, New York, 1981.
(b) D. Neckers, M.P. Doyle, Organic Chemistry, Wiley, New
York, 1977.
[22] (a) M.M. Hamed, Can. J. Appl. Spectrosc. 36 (1991) 1.
(b) H.H. Perkampus, B. Behjati, J. Heterocycl. Chem. 11
(1974) 511.
(c) J. March, Advanced Organic Chemistry, Wiley, New York,
1992.
[23] K. Maeda, E. Fischer, Helv. Chim. Acta 66 (1983) 1961.
[24] (a) T. Radhakrishnan, C.P. Prabhakaran, K.N. Rajasekharan,
Curr. Sci. 52 (1983) 1132.
[8] M. Wiebcke, D. Mootz, Acta Crystallogr. Sect. B B32 (1982)
2008.

´
R. Montalvo-Gonzalez, A. Ariza-Castolo / Journal of Molecular Structure 655 (2003) 375–389
389
(b) B. Kuncheria, P. Indrasenan, Polyhedron 7 (1988) 143.
(c) V.I. Letunov, J. Org. Chem. USSR 20 (1984) 145.
´ˇ ˇ
[25] J. Rohovec, P. Vojtısek, I. Lukes, Phosphurus Sulfur Silicon
[27] J.E. Rockley, L.A. Summers, Aust. J. Chem. 33 (1980) 1397.
[28] N. Katagiri, Y. Miura, R. Niwa, T. Kato, Chem. Pharm. Bull.
31 (1983) 538.
Relat. Elem. 148 (1999) 79.
[29] R.H. Abu-Eittah, M.M. Hammed, Bull. Chem. Soc. Jpn 57
(1984) 844.
[26] (a) P. Manns, Mikrochim. Acta (1958) 630.
(b) J.J.V. Eynde, D. Fromont, Bull. Soc. Chim. Belg. 106
(1997) 393.
[30] B.B. Mahapata, D. Panda, D.K. Das, B.K. Patel, S.C.
Chaudhry, Indian J. Chem. Soc. 65 (1988) 661.