4-Amino-3,5-diethyl-4H-1,2,4-triazole at 100 K: Chains of edge-fused R 44(10) and R44(20) rings

Article abstract of DOI:10.1107/S0108270107026339

The title compound, C6H12N4, has four crystallographically independent mol-ecules in the asymmetric unit. Inter-molecular N - H...N hydrogen bonds involving amino groups and triazole N atoms form a three-dimensional framework involving R 4 ⁴(10) and R 4 ⁴(20) rings. The hydrogen bonding is supported by weak C - H...π inter-actions. International Union of Crystallography 2007.

Full text of DOI:10.1107/S0108270107026339

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
November, 2005; Allen, 2002). In order to clarify the structure
of this type of compound, an X-ray structure determination of
the title compound, (I), has been carried out, and the results
are presented here. The structure has been con®rmed by IR,
1H NMR and 13C NMR spectroscopies and also by elemental
analysis.
ISSN 0108-2701
4-Amino-3,5-diethyl-4H-1,2,4-triazole
at 100 K: chains of edge-fused R44(10)
and R44(20) rings
Onur SËahin,a* Orhan Buyukgungor,a Selami SËaËsmaz,b
È
È È
È
Nurhan GumrukcËuogÆluc and Cihan Kantarb
The molecular structure and atom-numbering scheme for
(I) are shown in Fig. 1; selected bond lengths are given in
Table 1. Compound (I) crystallizes in the space group C2/c
with Z0 = 4, and the hydrogen bonding was analysed with the
aid of PLATON (Spek, 2003). The asymmetric unit contains
four independent molecules with statistically equivalent
metrical parameters but different conformations. The N1Ð
N4, N5ÐN8, N9ÐN12 and N13ÐN16 bond lengths (Table 1)
indicate single-bond character, whereas the N2ÐN3, N6ÐN7,
N10ÐN11 and N14ÐN15 bond lengths are indicative of
È
È
È
aDepartment of Physics, Ondokuz Mayõs University, TR-55139 Samsun, Turkey,
bDepartment of Chemistry, Rize University, Turkey, and cDepartment of Chemistry,
Giresun University, Turkey
Correspondence e-mail: onurs@omu.edu.tr
Received 11 March 2007
Accepted 29 May 2007
Online 23 June 2007
The title compound, C6H12N4, has four crystallographically
independent molecules in the asymmetric unit. Intermolecular
NÐHÁ Á ÁN hydrogen bonds involving amino groups and
triazole N atoms form a three-dimensional framework
involving R44(10) and R44(20) rings. The hydrogen bonding is
supported by weak CÐHÁ Á Áꢀ interactions.
signi®cant double-bond character. Similar NÐN and N
bond-length values have been observed in 4-amino-3-methyl-
N
5-(p-tolyl)-4H-1,2,4-triazole and 4-amino-3-methyl-5-phenyl-
Ê
4H-1,2,4-triazole [NÐN = 1.4090 (16) and 1.4081 (18) A, and
Ê
N = 1.3859 (19) and 1.396 (2) A; SËahin et al., 2006]. The H
N
atoms of the amino group form hydrogen bonds with the N
atoms of neighbouring triazole rings. The geometric param-
eters of the NÐHÁ Á ÁN hydrogen-bonding interactions are
given in Table 2.
Comment
1,2,4-Triazole and its derivatives have been used as starting
materials for the synthesis of many heterocycles (Desenko,
1995). The triazole ring, having strong ꢁ-donor and weak
ꢀ-acceptor properties, potentially has two different coordi-
nation modes through three N donor atoms coordinating to
metal ions (Van Diemen et al., 1991; Ding et al., 2004; Yi et al.,
2004; Ren et al., 2006). Recent interest in substituted 1,2,4-
triazoles has arisen in part from their transition metal
complexes with intriguing structures and speci®c magnetic
properties (Zhou et al., 2005, 2006). Many metal complexes
containing substituted 1,2,4-triazole have potential applica-
tions in molecular-based memory devices, displays and optical
switches owing to their spin crossover properties (Garcia et al.,
1997; Kahn & Martinez, 1998). Apart from their chemical
signi®cance, 1,2,4-triazole derivatives have been found to be
associated with diverse pharmacological properties, such as
anti-in¯ammatory, antifungal and antiviral activities (Massa et
al., 1992; Mahomed et al., 1993; Mullican et al., 1993). Some are
also known to exhibit analgesic, anticonvulsant, tranquilizing,
antidepressant, anxiolytic (Bradbury & Rivett, 1991; Sughen
& Yoloye, 1978; Stillings et al., 1986; Kane et al., 1988) or even
antitumour activities (Hatheway et al., 1978) and are applied in
therapy (e.g. alprazolam, estazolam, triazolam and adina-
zolam; Budavari et al., 1996). In spite of the chemical and
medicinal importance of this class of compounds, relatively
few crystal structures of 1,2,4-triazole derivatives have been
reported (Cambridge Structural Database, Version 5.27 of
Amino atom N4 in the reference molecule at (x, y, z) acts as
a hydrogen-bond donor, via H4B, to atom N7 within the
asymmetric unit and, via H4A, to atom N6v (symmetry codes
are de®ned in the footnote of Table 2), so forming a centro-
symmetric R44(10)(A) (Bernstein et al., 1995) ring centred at
3
1
(14, , ). Similarly, amino atom N12 acts as a hydrogen-bond
4
2
Figure 1
The molecular structure of (I), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 40% probability level.
Acta Cryst. (2007). C63, o431±o433
DOI: 10.1107/S0108270107026339
# 2007 International Union of Crystallography o431

organic compounds
Crystal data
3
Ê
V = 6457.6 (7) A
C6H12N4
Mr = 140.20
Monoclinic, C2=c
Z = 32
Mo Kꢄ radiation
1
Ê
a = 37.782 (2) A
ꢅ = 0.08 mm
T = 100 K
Ê
b = 9.2996 (4) A
Ê
c = 18.4055 (12) A
0.50 Â 0.48 Â 0.41 mm
ꢃ = 93.067 (5)ꢀ
Data collection
Stoe IPDSII diffractometer
16583 measured re¯ections
6331 independent re¯ections
4902 re¯ections with I > 2ꢁ(I)
Rint = 0.027
Figure 2
The packing of (I), showing the R44(10) and R44(20) ring patterns. Dashed
lines indicate hydrogen bonds. H atoms not involved in these interactions
and ethyl groups have been omitted for clarity. (Symmetry codes are
provided in Table 2.)
Re®nement
R[F2 > 2ꢁ(F2)] = 0.035
wR(F2) = 0.091
S = 1.04
6331 re¯ections
393 parameters
H atoms treated by a mixture of
independent and constrained
re®nement
3
Ê
Áꢆmax = 0.16 e A
3
Ê
0.23 e A
Áꢆmin
=
donor, via H12D, to atom N14 within the asymmetric unit and,
via H12E, to atom N15ii, so forming a second centrosymmetric
ring motif, this time of R44(10)(B) type, centred at (21, 0, 12 ). The
arrangement of the N8ÐH8CÁ Á ÁN10, N8ÐH8DÁ Á ÁN3i,
N16iiiÐH16AiiiÁ Á ÁN11 and N16iiiÐH16BiiiÁ Á ÁN2i interactions
can be described by the graph-set notation R44(10)(C). At the
same time, the N16ÐH16AÁ Á ÁN11iii, N16ÐH16BÁ Á ÁN2iv,
N8iiiÐH8CiiiÁ Á ÁN10iii and N8iiiÐH8DiiiÁ Á ÁN3iv interactions
constitute an R44(10)(D) ring. Finally, the N12ÐH12DÁ Á ÁN14,
N16ÐH16AÁ Á ÁN11iii, N12iiiÐH12DiiiÁ Á ÁN14iii and N16iiiÐ
H16AiiiÁ Á ÁN11 interactions produce an R44(20)(E) ring (Fig. 2).
Propagation of eight hydrogen bonds then forms a chain of
edge-fused rings, containing R44(10)(A)R44(10)(B)R44(10)(C)-
R44(10)(D) sequences of four edge-fused rings. Similarly, edge-
fused R44(10)(C) and R44(20)(E) rings form a chain running
along the c axis. In compound (I), interlinked C44(20) anti-
parallel chains zigzagging along the a axis are formed through
N4vÐH4AvÁ Á ÁN6, N8ÐH8CÁ Á ÁN10, N12ÐH12DÁ Á ÁN14 and
N16ÐH16BÁ Á ÁN2iv interactions. Amino atom N16 in the
molecule at (x, y, 12 + z) acts as hydrogen-bond donor, via
H16A, to N11ii, while N12ii acts as donor to N15, and in this
manner a C22(10) chain running parallel to the [001] direction
is generated.
Table 1
Selected bond lengths (A).
Ê
N1ÐN4
N2ÐN3
N5ÐN8
N6ÐN7
1.4130 (14)
N9ÐN12
N10ÐN11
N13ÐN16
N14ÐN15
1.4109 (14)
1.4016 (14)
1.4119 (14)
1.3984 (15)
1.3997 (15)
1.4118 (14)
1.3981 (15)
Table 2
Hydrogen-bond geometry (A, ).
ꢀ
Ê
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
N8ÐH8CÁ Á ÁN10
N8ÐH8DÁ Á ÁN3i
0.910 (17)
0.923 (19)
0.929 (16)
0.952 (16)
0.931 (17)
0.942 (17)
0.888 (16)
0.925 (18)
2.192 (17)
2.088 (19)
2.108 (16)
2.127 (17)
2.112 (18)
2.070 (17)
2.195 (17)
2.161 (18)
3.0975 (15)
2.9645 (16)
3.0295 (15)
3.0650 (16)
3.0256 (16)
3.0066 (15)
3.0803 (15)
3.0736 (16)
173.4 (14)
158.2 (15)
171.6 (14)
168.0 (13)
166.7 (14)
172.9 (14)
174.8 (14)
168.8 (14)
N12ÐH12DÁ Á ÁN14
N12ÐH12EÁ Á ÁN15ii
N16ÐH16AÁ Á ÁN11iii
N16ÐH16BÁ Á ÁN2iv
N4ÐH4AÁ Á ÁN6v
N4ÐH4BÁ Á ÁN7
Symmetry codes: (i) x; y ‡ 1; z ‡ 21; (ii) x ‡ 1; y; z ‡ 1; (iii) x ‡ 1; y; z ‡ 32; (iv)
x ‡ 1; y ‡ 1; z ‡ 1; (v) x ‡ 12; y ‡ 23; z ‡ 1.
These intermolecular interactions, namely an extensive
network of hydrogen bonds and ꢀ-ring interactions, are
responsible for constructing an in®nite three-dimensional
framework.
All H atoms bound to carbon were re®ned using a riding model,
Ê
with CÐH distances of 0.97 A [Uiso(H) = 1.2Ueq(parent atom)] for
Ê
methylene H atoms and 0.96 A [Uiso(H) = 1.5Ueq(parent atom)] for
methyl H atoms. The amino H atoms were located in a difference map
and were re®ned freely (distances are given in Table 2).
Data collection: X-AREA (Stoe & Cie, 2002); cell re®nement:
X-AREA; data reduction: X-RED (Stoe & Cie, 2002); program(s)
used to solve structure: SHELXS97 (Sheldrick, 1997); program(s)
used to re®ne structure: SHELXL97 (Sheldrick, 1997); molecular
graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to
prepare material for publication: WinGX (Farrugia, 1999).
Experimental
Propionic acid (18.5 g, 0.25 mol) was added to a solution of hydrazine
hydrate (21.5 g, 0.4 mol) and the mixture was re¯uxed for 5 h. On
cooling, a precipitate was formed, and this product was ®ltered off
and dried. Recrystallization from ethyl acetate gave a colourless
product (yield 62%). Single crystals of (I) were obtained from ethyl
acetate at room temperature by slow evaporation (m.p. 438±439 K).
IR (KBr, cm 1): 3235±3120 (vNH ), 1664 (vC N); 1H NMR (CDCl3): ꢂ
2
1.30 (t, 6H, 2CH3), 2.76 (g, 4H, 2CH2), 5.02 (s, 2H, NH2); 13C NMR
(CDCl3): ꢂ 156.21 (triazole C3 and triazole C5), 17.87 (CH2), 11.40
(CH3). Elemental analysis calculated for C6H12N4: C 51.41, H 8.63, N
39.97%; found: C 52.40, H 8.61, N 39.75%.
The authors acknowledge the Faculty of Arts and Sciences,
Ondokuz Mayõs University, Turkey, for the use of the Stoe
IPDSII diffractometer (purchased under grant No. F279 of the
University Research Fund).
ꢁ
o432 ËSahin et al. C6H12N4
Acta Cryst. (2007). C63, o431±o433

organic compounds
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ËSahin et al. C6H12N4 o433