Crystal structure and quantum chemical investigation of 4-(3,4-dichlorphenyl)-1,2,4-triazole

Article abstract of DOI:10.1007/s10947-006-0054-9

1,2,4-Triazole derivative substituted in the 4th position - 4-(3,4-dichlorphenyl)-1,2,4-tirazole - has been synthesized. Crystal and molecular structure of the compound were determined by single crystal X-ray diffraction. Molecular geometry optimization and effective charge calculations were performed by DFT methods.

Full text of DOI:10.1007/s10947-006-0054-9

Journal of Structural Chemistry, Vol. 46, No. 2, pp. 358-362, 2005
Original Russian Text Copyright © 2005 A. V. Virovets, E. V. Lider, V. N. Elokhina, M. B. Bushuev, and L. G. Lavrenova
CRYSTAL STRUCTURE AND QUANTUM CHEMICAL
INVESTIGATION OF 4-(3,4-DICHLORPHENYL)-1,2,4-TRIAZOLE
A. V. Virovets,1 E. V. Lider,2 V. N. Elokhina,3
M. B. Bushuev,1 and L. G. Lavrenova1
UDC 548.736+546.57
1,2,4-Triazole derivative substituted in the 4th position — 4-(3,4-dichlorphenyl)-1,2,4-tirazole — has been
synthesized. Crystal and molecular structure of the compound were determined by single crystal X-ray
diffraction. Molecular geometry optimization and effective charge calculations were performed by DFT
methods.
Keywords: 1,2,4-triazole, synthesis, crystal structure, quantum chemical calculations.
1,2,4-Triazole derivatives are applied as medicinal and photosensitive materials, as well as agents influencing plant
growth and development. Polynitrogen heterocycles, 1,2,4-triazole derivatives in particular, are potential ligands for the
preparation of magnetically active coordination compounds. 4-substituted 1,2,4-triazole derivatives are of special interest.
The absence of substituents at the N(1) and N(2) positions in the heterocycle provides bidentate — bridging coordination
making it possible to synthesize oligo- and polynuclear coordination compounds. Co(II), Ni(II) and Cu(II) complexes of these
types manifest ferro- and antiferromagnetic interactions between the paramagnetic centers [1-5]. Thermally induced spin
1
crossover Ⱥ1 œ 5Ɍ2 [6-8] is observed in a number of Fe(II) complexes with these ligands, which is accompanied by the
thermochromism (color change pink œ white). This contribution presents the synthesis and crystal structure of 4-(3,4-
diclorphenyl)-1,2,4-triazole (Clphtrz) — a potential ligand for the preparation of complexes possessing the above features.
Experimental. Synthesis of Clphtrz. 9.8 g (0.06 mole) of 3,4-dichloraniline and 5.3 g (0.06 mole) of diformyl-
hydrazine were placed in a round-bottom flask equipped with reflux, heated to 195qɋ and kept at this temperature for 40 min.
Then the flask was cooled to 80qɋ, and 20 ml of ethanol was added. The reaction mixture was transferred to a beaker and
cooled in a refrigerator after the addition of 100 ml of dry ether. The precipitate formed was filtered off (3.5 g). Additional
2.7 g of the product were obtained by ether precipitation from ethanol. The total yield of Clphtrz was 6.2 g or 50%.
Found, %: C 44.6; H 2.4; Cl 32.8; N 20.0. Calculated for C8H5Cl2N3, %: C 44.6; H 2.3; Cl 33.2; N 19.6.
IR spectrum (cm–1): 1500, 1560, 1600 (aromatic ring valence vibrations); 1685 (C=N); 1130 (C–N); 630, 670, 790
(C–Cl); 3100 (C–H).
NMR 1ɇ, ppm: 9.18 (s, 2ɇ, ɇ–3.5); 8.14 (d, 1ɇ, ɇ–2Ph, 4J = 2.5 Hz); 7.83 (d, 1ɇ, ɇ–5Ph, 3J = 8.8 Hz); 7.76 (dd, 1ɇ,
ɇ–6Ph, 3J = 8.8 Hz, 4J = 2.5 Hz).
NMR 13C, ppm: 141.32 (C–3.5); 133.80 (C–1Ph); 132.44 (C–Cl); 131.76 (C–5Ph); 130.39 (C–Cl); 123.11 (C–2Ph);
121.28 (C–6Ph).
Single crystals of Clphtrz suitable for X-ray diffraction study were obtained by the slow crystallization from ethanol
solutions.
1Nikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences, Novosibirsk;
2
3
vir@che.nsk.su. Novosibirsk State University. Favorskii Institute of Chemistry, Siberian Division, Russian Academy of
Sciences, Irkutsk. Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 2, pp.366-370, March-April, 2005. Original
article submitted February 17, 2004.
358
0022-4766/05/4602-0358 © 2005 Springer Science+Business Media, Inc.

Research techniques. IR spectrum of Clphtrz was recorded in KBr pellets with a Specord 75 IR spectrophotometer.
1ɇ and 13ɋ NMR spectra were obtained using a Bruker DPX-400 spectrometer (400.13 MHz 1ɇ; 100.61 MHz 13ɋ) in DMSO-d6.
Structural investigation. A colorless needle-like single crystal of 0.62u0.16u0.14 mm size was mounted on a
automated four-circle diffractometer Enraf Nonius CAD-4 for the unit cell measurement and intensity data collection (MoKD,
graphite monochromator, room temperature, standard technique). The crystal is monoclinic, the space group P21/c; a =
7.235(3) Å, b = 14.139(9) Å, c = 8.986(5) Å; E = 102.65(4)q, V = 896.9(8) Å3, Z = 4, Ucalc = 1.585 g/cm3 for the composition
C8H5Cl2N3, P = 0.673 mm–1. Adsorption correction appeared to be negligible and was not considered. A total of 2592
reflections were measured within 2T = 50q. The structure was solved by the direct method and refined anisotropically for
non-hydrogen atoms in the full-matrix approximation using SHELX-97 program [9]. Hydrogen atoms were set into idealized
positions. The final agreement factors were: R1 = 0.0692, wR2 = 0.1602 for 850 Fhkl t 4V(F), R1 = 0.1179, wR2 = 0.1918,
GOOF = 0.853 for all 1570 independent reflections. Atomic coordinates are reported in Table 1, bond lengths and selected
valence angles — in Table 2.
Quantum chemical study. The quantum chemical calculations were made with GAUSSIAN-98 package [10] using
the exchange-correlation functionals B3LYP and B3PW91. 6-311+G(2d, p) wave function set [10] was used as the basis.
Charge calculations on the atoms were performed according to Mulliken [11], Merz–Kollman–Singh [12,13] and Breneman
[14] schemes after complete molecular geometry optimization done.
Discussion. The structure of Clphtrz molecule is shown in Fig. 1. Both cycles of the molecule are planar and
inclined to each other at the angle of 45.5(2)q that is apparently caused by sterical reasons. Bond lengths and angles have
usual values. The interatomic distances in the triazole fragment suggest the presence of two double bonds N1–C1 and N2–C2.
The molecular packing is shown in Fig. 2. Non-valence contacts N…H(C) of 2.46 Å and 2.59 Å length are found in
the crystal, which are likely to indicate the presence of weak hydrogen bonds.
Calculated bond lengths and angles are reported in Table 2. In general, they are in a good agreement with the
experimental structural data. Minor mismatches can be due to the functional choice and packing effects.
Atomic charges are given in Table 3. It is seen that the charges calculated by the methods [12-14] match well
mutually, but differ significantly from that calculated according to the scheme [11]. Thus, atoms N(1) and N(2) gain the largest
and virtually equal negative charges favoring the bidentate bridging coordination of Clphtrz to metal atoms in the complex
TABLE 1. Non-Hydrogen Atom Coordinates (u104) and Equivalent Thermal Parameters (Å2u103) in the Clphtrz Structure
Atom
x
y
z
Ueq*
Cl1
Cl2
C1
C2
C3
C4
C5
C6
C7
C8
N1
N2
N3
6036(2)
5361(3)
9987(9)
8816(9)
8112(8)
8298(8)
7627(8)
6771(8)
6543(8)
7230(8)
10532(8)
9745(8)
8881(6)
–571(1)
1612(1)
2011(3)
914(4)
–8151(2)
–7703(2)
–1868(6)
–756(6)
67(1)
74(1)
57(2)
56(1)
45(1)
49(1)
48(1)
49(1)
51(1)
49(1)
61(1)
64(1)
46(1)
798(3)
–3599(5)
–3758(5)
–5154(6)
–6385(5)
–6204(6)
–4798(6)
–429(5)
–174(3)
–585(3)
–46(4)
926(3)
1340(3)
2164(3)
1448(3)
1226(3)
299(5)
–2161(4)
*Ueq is set to one third of the normalized Uij tensor trace.
359

TABLE 2. Experimental and Calculated Bond Lengths, Å, and Selected Valence Angles, deg, in the Structure of Clphtrz
Length, Å
Optimization
Length, Å
Optimization
Bond
Experiment
Bond
Experiment
B3LYP
B3PW91
B3LYP
B3PW91
N(1)–N(2)
C(1)–N(1)
C(1)–N(3)
C(2)–N(2)
C(2)–N(3)
C(3)–C(4)
C(3)–C(8)
1.393(6)
1.285(7)
1.361(6)
1.281(7)
1.348(6)
1.391(7)
1.362(7)
1.384
1.302
1.374
1.302
1.373
1.393
1.391
1.375
1.301
1.369
1.301
1.369
1.391
1.388
C(3)–N(3)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
Cl(1)–C(6)
Cl(2)–C(7)
1.424(6)
1.371(7)
1.374(7)
1.399(7)
1.382(7)
1.727(5)
1.726(5)
1.419
1.386
1.391
1.395
1.390
1.741
1.741
1.414
1.384
1.389
1.394
1.388
1.728
1.728
Value
Value
Angle
Experiment
Optimization
Angle
Experiment
Optimization
B3LYP
B3PW91
B3LYP
B3PW91
C(1)–N(1)–N(2)
C(2)–N(2)–N(1)
C(1)–N(3)–C(3)
C(2)–N(3)–C(1)
C(2)–N(3)–C(3)
106.5(4)
106.4(4)
128.2(4)
103.0(4)
128.6(4)
107.3
107.3
128.2
103.6
128.1
107.4
107.4
128.2
103.7
128.1
N(1)–C(1)–N(3)
N(2)–C(2)–N(3)
C(4)–C(3)–N(3)
C(8)–C(3)–C(4)
C(8)–C(3)–N(3)
111.7(4)
112.3(5)
119.0(5)
120.9(5)
120.1(4)
110.9
110.9
120.2
120.1
119.7
110.7
110.8
120.2
120.1
119.6
Fig. 1. Structure of Clphtrz molecule; ellipsoids of 50% probability.
compounds. Chlorine atom charges are small in absolute value that, taking also into account the charges on the neighboring
atoms C(6) and C(7), enables one to postulate a comparatively small polarity of Cl–C bonds. Atoms C(4), C(5) and C(8) bear
a minor negative charge. Allowing for the fact that the charges on hydrogen atoms equal approximately 0.1 (for all
calculation techniques), this promotes the formation of weak intermolecular hydrogen bonds with N(1) and N(2) atoms of
neighboring Clphtrz molecules.
The authors are grateful to Prof. S. G. Kozlova for continuous interest to this work and valuable discussions.
The study was conducted in the frame of Presidium RAS Program.
360

Fig. 2. Crystal molecular packing as viewed along the a axis. Contacts N...H of 2.46 Å and
2.59 Å lengths are shown as dashed lines.
TABLE 3. Effective Atomic Charges for the Optimized Molecular Geometry of Clphtrz
Atom
Scheme [11]
Scheme [12, 13]
Scheme [14]
B3LYP
B3PW91
B3LYP
B3PW91
B3LYP
B3PW91
N(1)
N(2)
C(1)
C(2)
N(3)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
Cl(1)
Cl(2)
–0.195
–0.193
0.027
–0.194
–0.191
–0.009
–0.019
0.215
–0.323
–0.327
0.138
–0.315
–0.319
0.121
–0.343
–0.341
0.278
–0.335
–0.331
0.254
0.019
0.152
0.133
0.270
0.243
0.083
0.212
0.198
–0.039
0.049
–0.026
0.049
–0.423
–0.045
–0.970
0.923
–0.663
–0.020
–1.062
0.967
–0.191
–0.038
–0.121
0.052
–0.152
–0.073
–0.111
0.035
–0.116
–0.083
0.087
–0.128
–0.090
0.080
0.476
0.411
0.046
0.043
0.080
0.070
–0.536
0.094
–0.482
0.156
–0.008
–0.066
–0.064
–0.035
–0.056
–0.054
–0.094
–0.094
–0.084
–0.103
–0.085
–0.074
0.102
0.165
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