7-Amino-2,5-dimethyl­pyrazolo[1,5-a]pyrimidine hemihydrate redetermined at 120 K: a three-dimensional hydrogen-bonded framework

Portilla, J.; Quiroga, J.; Cobo, J.; Low, J.N.; Glidewell, C.

doi:10.1107/S0108270106005373

organic compounds

STRUCTURAL
CHEMISTRY

ISSN: 2053-2296

Volume 62| Part 4| April 2006| Pages o186-o189

doi:10.1107/S0108270106005373

7-Amino-2,5-dimethylpyrazolo[1,5-a]pyrimidine hemihydrate redetermined at 120 K: a three-dimensional hydrogen-bonded framework

Jaime Portilla,^a Jairo Quiroga,^a Justo Cobo,^b John N. Low ^c and Christopher Glidewell ^d ^*

^aGrupo de Investigación de Compuestos Heterocíclicos, Departamento de Química, Universidad de Valle, AA 25360 Cali, Colombia, ^bDepartamento de Química Inorgánica y Orgánica, Universidad de Jaén, 23071 Jaén, Spain, ^cDepartment of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB24 3UE, Scotland, and ^dSchool of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland
^*Correspondence e-mail: cg@st-andrews.ac.uk

(Received 14 February 2006; accepted 15 February 2006; online 11 March 2006)

In the title compound, C₈H₁₀N₄·0.5H₂O, where the water molecules lie on twofold rotation axes in the space group C2, the components are linked by three hydrogen bonds, one each of O—H⋯N, N—H⋯N and N—H⋯O types, into a complex three-dimensional framework structure.

Comment

Pyrazolo[1,5-a]pyrimidines are purine analogues which exhibit a number of useful properties as antimetabolites in purine biochemical reactions; they are of particular interest because of their antitrypanosomal (Novinson et al., 1976 ) and antischistosomal activities (Senga et al., 1981 ). Such interesting biological properties have prompted the development of new and efficient general procedures for the synthesis of pyrazolo[1,5-a]pyrimidine derivatives (Al-Shiekh et al., 2004 ; Makarov et al., 2005 ). We present here the structure of 7-amino-2,5-dimethylpyrazolo[1,5-a]pyrimidine, (I), prepared by the solvent-free cyclocondensation reaction between 5-amino-3-methyl-1H-pyrazole and 3-aminocrotononitrile induced by microwave irradiation, and crystallized from ethanol as the hemihydrate.

The structure of (I) was determined many years ago using diffraction data collected at ambient temperature (Mornon et al., 1975 ). The coordinates and displacement parameters for the H atoms bonded to C and O atoms were all refined and the refinement converged to R = 0.058 with a data/parameter ratio of only 5.94, giving typical s.u. values on the distances and angles of 0.01 Å and 1.5°, respectively. Although three intermolecular hydrogen bonds were identified, the authors gave no analysis or discussion of their structural consequences.

We have now taken the opportunity to redetermine this structure using diffraction data collected at 120 K, and the resulting refinement, which converged to R = 0.037 for a data/parameter ratio of 9.62, gives much greater geometric precision, with typical s.u. values on distances and angles of 0.002 Å and 0.15°, respectively. We report here this redetermination, with a detailed description of the supramolecular structure.

Within the heterocyclic component, the bond distances (Table 1) show a number of deviations from the pattern expected if the bond-localized form (I) (see scheme) is the correct representation. In particular, the C3A—N4 bond, which is formally a single bond, is not very much longer than the N1—C2 and N4—C5 bonds, both of which are formally double bonds; similarly, the lengths of the C2—C3 and C5—C6 bonds, which are formally single bonds, differ very little from those of the C3—C3A and C6—C7 bonds, which are formally double bonds. This pattern points to a considerable degree of aromatic type 10-π electron delocalization. Also noteworthy is the difference between the two exocyclic angles at atom C7, a difference which has no obvious explanation. All these metrical observations closely mimic those obtained, at much lower precision, from the ambient-temperature determination (Mornon et al., 1975), although some of the geometric and displacement parameters involving H atoms in that report are clearly unreliable.

As reported previously, the water molecules lie on twofold rotation axes in space group C2, with the heterocyclic component in a general position. For the sake of convenience, the reference water molecule has been selected as that lying across the rotation axis along ( $[1\over2]$ , y, $[1\over2]$ ), with the two independent molecular components linked by an O—H⋯N hydrogen bond (Fig. 1 and Table 1). Three independent hydrogen bonds (Table 2), one each of O—H⋯N, N—H⋯N and N—H⋯O types, link the molecular components into a three-dimensional framework of some complexity. However, descriptive analysis of the formation of this framework is markedly simplified by the identification of a number of simple substructures in zero, one and two dimensions, whose combination generates the overall framework structure.

A basic building block in the supramolecular structure is a cyclic dimer containing only the heterocyclic component. Amine atom N7 in the bicyclic molecule at (x, y, z) acts as a hydrogen-bond donor, via H7A, to ring atom N1 at (2 − x, y, 2 − z), so forming a cyclic R₂²(10) (Bernstein et al., 1995 ) dimer (Fig. 2). The water molecules act as twofold donors in O—H⋯N hydrogen bonds and as twofold acceptors in N—H⋯O hydrogen bonds (Table 2), and the resulting linking of the water molecules and the heterocycles generates three independent chains, whose combination leads to the formation of the three-dimensional framework.

The water O atom at ( $[1\over2]$ , y, $[1\over2]$ ) accepts hydrogen bonds from amine atoms N7 in the two heterocyclic molecules at (− $[{1\over 2}]$ + x, $[{1\over 2}]$ + y, z) and ( $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, 1 − z). These molecules are components of the R₂²(10) dimers lying across the twofold rotation axes along ( $[1\over2]$ , y, 1) and ( $[1\over2]$ , y, 0), and these dimers in turn also act as hydrogen-bond donors to the O atoms at ( $[1\over2]$ , y, $[3\over2]$ ) and ( $[1\over2]$ , y, − $[3\over2]$ ), respectively. In this manner, a chain of linked dimers running parallel to the [001] direction is generated by successive twofold rotations (Fig. 3).

The same water O atom at ( $[1\over2]$ , y, $[1\over2]$ ) acts as a hydrogen-bond donor to pyridine atoms N4 in the molecules at (x, y, z) and (1 − x, y, 1 − z), respectively, which are themselves components of the R₂²(10) dimers lying across the rotation axes along (1, y, 1) and (0, y, 0). Propagation of these hydrogen bonds by successive rotations then generates a second chain of linked dimers, this time running parallel to the [101] direction (Fig. 4). The combination of the [001] and [101] chains (Figs. 3 and 4) generates the first of the two-dimensional substructures in the form of a (010) sheet.

In the final substructure, which is also two-dimensional, the reference water O atom at ( $[1\over2]$ , y, $[1\over2]$ ) acts as a hydrogen-bond donor to the heterocyclic molecules at (x, y, z) and (1 − x, y, 1 − z), and as a hydrogen-bond acceptor from the corresponding molecules at (− $[{1\over 2}]$ + x, $[{1\over 2}]$ + y, z) and ( $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, 1 − z), and propagation of these two hydrogen bonds in combination generates a (001) sheet built from a single type of R₈⁸(32) ring (Fig. 5). The combination of (010) and (001) sheets is sufficient to generate a single three-dimensional framework structure.

Figure 1
The independent molecular components of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. Atom O1 lies on a twofold rotation axis (see Comment).

Figure 2
Part of the crystal structure of (I), showing the formation of an R₂²(10) dimer. For the sake of clarity, the unit-cell outline, the water molecule and H atoms bonded to C atoms have all been omitted. Atoms marked with an asterisk are at the symmetry position (2 − x, y, 2 − z).

Figure 3
Part of the crystal structure of (I), showing the formation of a [001] chain of linked R₂²(10) dimers. For the sake of clarity, H atoms not involved in the motif shown have been omitted. Atoms marked with an asterisk (*), a hash (#), a dollar sign ($) or an ampersand (&) are at the symmetry positions (− $[{1\over 2}]$ + x, $[{1\over 2}]$ + y, z), ( $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, 2 − z), ( $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, 1 − z) and (− $[{1\over 2}]$ + x, $[{1\over 2}]$ + y, −1 + z), respectively. Atoms O1A and O1B are at ( $[{1\over 2}]$ , y, $[{3\over 2}]$ ) and ( $[{1\over 2}]$ , y, − $[{1\over 2}]$ ), respectively.

Figure 4
Part of the crystal structure of (I), showing the formation of a [101] chain of linked R₂²(10) dimers. For the sake of clarity, H atoms bonded to C atoms have been omitted. Atoms marked with an asterisk (*), a hash (#) or a dollar sign ($) are at the symmetry positions (2 − x, y, 2 − z), (1 − x, y, 1 − z) and (−1 + x, y, −1 + z), respectively.

Figure 5
A stereoview of a part of the crystal structure of (I), showing the formation of a (001) sheet of R₈⁸(32) rings. For the sake of clarity, H atoms bonded to C atoms have been omitted.

Experimental

An intimate mixture of 5-amino-3-methyl-1H-pyrazole (194 mg, 2 mmol) and 3-aminocrotononitrile (328 mg, 4 mmol) was placed in an open Pyrex glass vessel and irradiated in a domestic microwave oven for 2.5 min (at 600 W). The reaction mixture was then extracted with ethanol and, after removal of the solvent, the product was crystallized from ethanol as white crystals suitable for single-crystal X-ray diffraction (yield 92%, m.p. 470–472 K). MS: (30 eV) m/z (%) = 162 (100, M⁺), 161 (24), 147 (5), 134 (11), 122 (26).

Crystal data

C₈H₁₀N₄·0.5H₂O
M_r = 171.21
Monoclinic, C 2
a = 16.0851 (5) Å
b = 7.9458 (3) Å
c = 8.0003 (3) Å
β = 117.309 (2)°
V = 908.55 (6) Å³
Z = 4
D_x = 1.252 Mg m⁻³
Mo Kα radiation
Cell parameters from 1116 reflections
θ = 4.5–27.5°
μ = 0.09 mm⁻¹
T = 120 (2) K
Block, colourless
0.54 × 0.36 × 0.20 mm

Data collection

Nonius KappaCCD diffractometer
φ and ω scans
Absorption correction: multi-scan(SADABS; Sheldrick, 2003 )T_min = 0.967, T_max = 0.983
6163 measured reflections
1116 independent reflections
1032 reflections with I > 2σ(I)
R_int = 0.024
θ_max = 27.5°
h = −20 → 20
k = −10 → 10
l = −9 → 10

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.090
S = 1.06
1116 reflections
116 parameters
H-atom parameters constrained
w = 1/[σ²(F_o²) + (0.0579P)² + 0.2034P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

N1—C2	1.342 (2)
C2—C3	1.401 (3)
C3—C3A	1.392 (3)
C3A—N4	1.355 (2)
N4—C5	1.332 (2)
C5—C6	1.393 (3)
C6—C7	1.390 (2)
C7—N7A	1.371 (2)
N7A—N1	1.368 (2)
C3A—N7A	1.384 (2)
C7—N7	1.333 (2)

N7—C7—N7A	117.38 (15)
N7—C7—C6	127.60 (16)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N4	0.96	1.81	2.763 (2)	172
N7—H7A⋯N1ⁱ	0.88	2.21	2.971 (2)	144
N7—H7B⋯O1ⁱⁱ	0.88	2.01	2.877 (2)	168
Symmetry codes: (i) -x+2, y, -z+2; (ii) $[x+{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ .

The systematic absences permitted C2, Cm and C2/m as possible space groups; C2 was selected and then confirmed by the successful structure analysis. All H atoms were located from difference maps and then treated as riding atoms, with C—H distances of 0.95 (aromatic) or 0.98 Å (methyl), N—H distances of 0.88 Å, and U_iso(H) values of 1.2U_eq(C,N), 1.5U_eq(O) or 1.5U_eq(methyl C). In the absence of significant anomalous scattering, the Flack (1983 ) parameter was indeterminate (Flack & Bernardinelli, 2000 ), and the Friedel equivalent reflections were merged prior to the final refinement. Accordingly, it was not possible to establish the absolute configuration of the asymmetric unit (Jones, 1986 ).

Data collection: COLLECT (Hooft, 1999 ); cell refinement: DENZO (Otwinowski & Minor, 1997 ) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: OSCAIL (McArdle, 2003 ) and SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003 ); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S0108270106005373/sk3006sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S0108270106005373/sk3006Isup2.hkl

Comment top

Pyrazolo[1,5-a]pyrimidines are purine analogues which exhibit a number of useful properties as antimetabolites in purine biochemical reactions; they are of particular interest because of their antitrypanosomal (Novinson et al., 1976) and antischistosomal activities (Senga et al., 1981). Such interesting biological properties have prompted the development of new and efficient general procedures for the synthesis of pyrazolo[1,5-a]pyrimidine derivatives (Al-Shiekh et al., 2004; Makarov et al., 2005). We present here the structure of 7-amino-2,5-dimethylpyrazolo[1,5-a]pyrimidine, (I), prepared by the solvent-free cyclocondensation reaction between 5-amino-3-methyl-1H-pyrazole and 3-aminocrotononitrile induced by microwave irradiation, and crystallized from ethanol as the hemihydrate

The structure of the (I) was determined many years ago using diffraction data collected at ambient temperature (Mornon et al., 1975). The coordinates and displacement parameters for the H atoms bonded to C and O atoms were all refined and the refinement converged to R = 0.058 with a data/parameter ratio of only 5.94, giving typical s.u. values on the distances and angles of 0.01 Å and 1.5°, respectively. Although three intermolecular hydrogen bonds were identified, the authors gave no analysis or discussion of their structural consequences.

We have now taken the opportunity to redetermine this structure using diffraction data collected at 120 K, and the resulting refinement, which converged to R = 0.037 for a data/parameter ratio of 9.62, gives much greater geometric precision with typical s.u. values on distances and angles of 0.002 Å and 0.15°, respectively. We report here this redetermination, with a detailed description of the supramolecular structure.

Within the heterocyclic component, the bond distances (Table 1) show a number of deviations from the pattern expected if the bond-localized form (I) (see scheme) is the correct representation. In particular, the C3A—N4 bond, which is formally a single bond, is not very much longer than the N1—C2 and N4—C5 bonds, both of which are formally double bonds; similarly, the lengths of the C2—C3 and C5—C6 bonds, which are formally single bonds, differ very little from those of the C3—C3A and C6—C7 bonds, which are formally double bonds. This pattern points to a considerable degree of aromatic type 10-π electron delocalization. Also noteworthy is the difference between the two exocyclic angles at atom C7, a difference which has no obvious explanation. All these metrical observations closely mimic those reported, at much lower precision, from the ambient-temperature determination (Mornon et al., 1975), although some of the geometric and displacement parameters involving H atoms in that report are clearly unreliable.

As reported previously, the water molecules lie on twofold rotation axes in space group C2, with the heterocyclic component in a general position. For the sake of convenience, the reference water molecule has been selected at that lying across the rotation axis along (1/2, y, 1/2), with the two independent molecular components linked by an O—H···N hydrogen bond (Fig. 1 and Table 1). Three independent hydrogen bonds (Table 1), one each of O—H.·N, N—H···N and N—H···O types, link the molecular components into a three-dimensional framework of some complexity. However, descriptive analysis of the formation of this framework is markedly simplified by the identification of a number of simple substructures in zero, one and two dimensions, whose combination generates the overall framework structure.

A basic building block in the supramolecular structure is a cyclic dimer containing only the heterocyclic component. Amine atom N7 in the bicyclic molecule at (x, y, z) acts as a hydrogen-bond donor, via H7A, to ring atom N1 at (2 − x, y, 2 − z), so forming a cyclic R²₂(10) (Bernstein et al., 1995) dimer (Fig. 2). The water molecules act as twofold donors in O—H···N hydrogen bonds and as twofold acceptors in N—H···O hydrogen bonds (Table 2), and the resulting linking of the water molecules and the heterocycles generates three independent chains, whose combination leads to the formation of the three-dimensional framework.

The water O atom at (1/2, y, 1/2) accepts hydrogen bonds from amine atoms N7 in the two heterocyclic molecules at (−1/2 + x, 1/2 + y, z) and (3/2 − x, 1/2 + y, 1 − z). These molecules are components of the R²₂(10) dimers lying across the twofold rotation axes along (1/2, y, 1) and (1/2, y, 0), and these dimers in turn also act as hydrogen-bond donors to the O atoms at (1/2, y, 3/2) and (1/2, y, −3/2) respectively. In this manner a chain of linked dimers running parallel to the [001] direction is generated by successive twofold rotations (Fig. 3).

The same water O atom at (1/2, y, 1/2) acts as hydrogen-bond donor to pyridine atoms N4 in the molecules at (x, y, z) and (1 − x, y, 1 − z), respectively, which are themselves components of the R²₂(10) dimers lying across the rotation axes along (1, y, 1) and (0, y, 0). Propagation of these hydrogen bonds by successive rotations then generates a second chain of linked dimers, this time running parallel to the [101] direction (Fig. 4). The combination of the [001] and [101] chains (Figs. 3 and 4) generates the first of the two-dimensional substructures in the form of a (010) sheet.

In the final substructure, which is also two-dimensional, the reference water O atom at (1/2, y, 1/2) acts as hydrogen-bond donor to the heterocyclic molecules at (x, y, z) and (1 − x, y, 1 − z), and as hydrogen-bond acceptor from the corresponding molecules at (−1/2 + x, 1/2 + y, z) and (3/2 − x, 1/2 + y, 1 − z), and propagation of these two hydrogen bonds in combination generates a (001) sheet built from a single type of R⁸₈(32) ring (Fig. 5). The combination of (010) and (001) sheets is sufficient to generate a single three-dimensional framework structure.

Experimental top

An intimate mixture of 5-amino-3-methyl-1H-pyrazole (194 mg, 2 mmol) and 3-aminocrotononitrile (328 mg, 4 mmol) was placed in an open Pyrex glass vessel and irradiated in a domestic microwave oven for 2.5 min (at 600 W). The reaction mixture was then extracted with ethanol, and after removal of the solvent, the product (I) was crystallized from ethanol as white crystals suitable for single-crystal X-ray diffraction (yield 92%, m.p. 470–472 K). MS: (30 eV) m/z (%) = 162 (100, M+), 161 (24), 147 (5), 134 (11), 122 (26).

Computing details top

Data collection: COLLECT (Hooft, 1999); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).

Figures top

	Fig. 1. The independent molecular components of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. Atom O1 lies on a twofold rotation axis (see text).
	Fig. 2. Part of the crystal structure of (I), showing the formation of a R²₂(10) dimer. For the sake of clarity, the unit-cell outline, the water molecule and H atoms bonded to C atoms have all been omitted. Atoms marked with an asterisk are at the symmetry position (2 − x, y, 2 − z).
	Fig. 3. Part of the crystal structure of (I), showing the formation of a [001] chain of linked R²₂(10) dimers. For the sake of clarity, the H atoms not involved in the motif shown have been omitted. Atoms marked with an asterisk (*), a hash (#), a dollar sign ($) or an ampersand (&) are at the symmetry positions (−1/2 + x, 1/2 + y, z), (3/2 − x, 1/2 + y, 2 − z), (3/2 − x, 1/2 + y, 1 − z) and (−1/2 + x, 1/2 + y, −1 + z), respectively.
	Fig. 4. Part of the crystal structure of (I), showing the formation of a [101] chain of linked R²₂(10) dimers. For the sake of clarity, H atoms bonded to C atoms have been omitted. The atoms marked with an asterisk (*), a hash (#) or a dollar sign ($) are at the symmetry positions (2 − x, y, 2 − z), (1 − x, y, 1 − z) and (−1 + x, y, −1 + z), respectively.
	Fig. 5. A stereoview of a part of the crystal structure of (I), showing the formation of a (001) sheet of R⁸₈(32) rings. For the sake of clarity, H atoms bonded to C atoms have been omitted.

7-Amino-2,5-dimethylpyrazolo[1,5-a]pyrimidine hemihydrate top

Crystal data top

C₈H₁₀N₄·0.5H₂O	F(000) = 364
M_r = 171.21	D_x = 1.252 Mg m⁻³
Monoclinic, C2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C 2y	Cell parameters from 1116 reflections
a = 16.0851 (5) Å	θ = 4.5–27.5°
b = 7.9458 (3) Å	µ = 0.09 mm⁻¹
c = 8.0003 (3) Å	T = 120 K
β = 117.309 (2)°	Block, colourless
V = 908.55 (6) Å³	0.54 × 0.36 × 0.20 mm
Z = 4

Data collection top

Nonius KappaCCD diffractometer	1116 independent reflections
Radiation source: Bruker-Nonius FR91 rotating anode	1032 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.024
Detector resolution: 9.091 pixels mm^-1	θ_max = 27.5°, θ_min = 4.5°
ϕ and ω scans	h = −20→20
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	k = −10→10
T_min = 0.967, T_max = 0.983	l = −9→10
6163 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.090	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.0579P)² + 0.2034P] where P = (F_o² + 2F_c²)/3
1116 reflections	(Δ/σ)_max < 0.001
116 parameters	Δρ_max = 0.17 e Å⁻³
1 restraint	Δρ_min = −0.20 e Å⁻³

Crystal data top

C₈H₁₀N₄·0.5H₂O	V = 908.55 (6) Å³
M_r = 171.21	Z = 4
Monoclinic, C2	Mo Kα radiation
a = 16.0851 (5) Å	µ = 0.09 mm⁻¹
b = 7.9458 (3) Å	T = 120 K
c = 8.0003 (3) Å	0.54 × 0.36 × 0.20 mm
β = 117.309 (2)°

Data collection top

Nonius KappaCCD diffractometer	1116 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	1032 reflections with I > 2σ(I)
T_min = 0.967, T_max = 0.983	R_int = 0.024
6163 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	1 restraint
wR(F²) = 0.090	H-atom parameters constrained
S = 1.06	Δρ_max = 0.17 e Å⁻³
1116 reflections	Δρ_min = −0.20 e Å⁻³
116 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.5000	0.4489 (2)	0.5000	0.0264 (4)
N1	0.88429 (10)	0.2722 (2)	0.9820 (2)	0.0269 (3)
N4	0.65962 (10)	0.26477 (18)	0.5803 (2)	0.0283 (3)
N7	0.93536 (10)	0.1362 (2)	0.7256 (2)	0.0321 (4)
N7A	0.82186 (10)	0.24015 (17)	0.7987 (2)	0.0232 (3)
C2	0.83100 (13)	0.3410 (2)	1.0528 (3)	0.0286 (4)
C3	0.73665 (13)	0.3543 (2)	0.9203 (3)	0.0309 (4)
C3A	0.73131 (11)	0.2868 (2)	0.7552 (2)	0.0256 (4)
C5	0.68064 (12)	0.1943 (2)	0.4533 (3)	0.0286 (4)
C6	0.77084 (12)	0.1459 (3)	0.4915 (3)	0.0281 (4)
C7	0.84535 (11)	0.1708 (2)	0.6691 (2)	0.0250 (4)
C21	0.87585 (15)	0.3949 (3)	1.2553 (3)	0.0391 (5)
C51	0.60139 (13)	0.1680 (3)	0.2592 (3)	0.0406 (5)
H1	0.5531	0.3776	0.5331	0.040*
H3	0.6870	0.3996	0.9392	0.037*
H6	0.7815	0.0955	0.3954	0.034*
H7A	0.9770	0.1579	0.8421	0.038*
H7B	0.9531	0.0917	0.6464	0.038*
H21A	0.9232	0.3122	1.3318	0.059*
H21B	0.8280	0.4028	1.2986	0.059*
H21C	0.9055	0.5051	1.2675	0.059*
H51A	0.5704	0.0608	0.2550	0.061*
H51B	0.6259	0.1659	0.1675	0.061*
H51C	0.5562	0.2601	0.2288	0.061*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0218 (7)	0.0284 (9)	0.0316 (9)	0.000	0.0144 (7)	0.000
N1	0.0279 (7)	0.0281 (7)	0.0247 (7)	0.0020 (6)	0.0122 (6)	−0.0009 (6)
N4	0.0231 (7)	0.0270 (8)	0.0341 (8)	0.0002 (6)	0.0126 (6)	0.0016 (7)
N7	0.0249 (7)	0.0404 (9)	0.0323 (8)	0.0015 (7)	0.0143 (6)	−0.0112 (7)
N7A	0.0227 (6)	0.0230 (7)	0.0249 (7)	0.0018 (5)	0.0118 (5)	−0.0012 (6)
C2	0.0357 (9)	0.0281 (9)	0.0272 (9)	0.0042 (7)	0.0189 (7)	0.0018 (7)
C3	0.0324 (9)	0.0317 (10)	0.0359 (9)	0.0067 (8)	0.0218 (8)	0.0029 (8)
C3A	0.0241 (8)	0.0235 (8)	0.0323 (9)	0.0031 (7)	0.0156 (7)	0.0032 (7)
C5	0.0275 (8)	0.0241 (9)	0.0318 (9)	−0.0016 (7)	0.0115 (7)	−0.0004 (7)
C6	0.0288 (8)	0.0277 (8)	0.0277 (8)	−0.0024 (7)	0.0128 (7)	−0.0065 (7)
C7	0.0245 (8)	0.0235 (9)	0.0295 (9)	0.0014 (7)	0.0145 (7)	−0.0016 (7)
C21	0.0442 (11)	0.0452 (11)	0.0312 (10)	0.0071 (9)	0.0200 (9)	−0.0035 (9)
C51	0.0303 (9)	0.0429 (12)	0.0386 (11)	−0.0014 (9)	0.0071 (8)	−0.0063 (10)

Geometric parameters (Å, º) top

N1—C2	1.342 (2)	C21—H21A	0.98
C2—C3	1.401 (3)	C21—H21B	0.98
C3—C3A	1.392 (3)	C21—H21C	0.98
C3A—N4	1.355 (2)	C3—H3	0.95
N4—C5	1.332 (2)	C5—C51	1.504 (2)
C5—C6	1.393 (3)	C51—H51A	0.98
C6—C7	1.390 (2)	C51—H51B	0.98
C7—N7A	1.371 (2)	C51—H51C	0.98
N7A—N1	1.368 (2)	C6—H6	0.95
C3A—N7A	1.384 (2)	N7—H7A	0.88
C7—N7	1.333 (2)	N7—H7B	0.88
C2—C21	1.502 (3)	O1—H1	0.96

C2—N1—N7A	103.37 (14)	C6—C5—C51	119.48 (17)
N1—C2—C3	113.07 (16)	C5—C51—H51A	109.5
N1—C2—C21	119.20 (16)	C5—C51—H51B	109.5
C3—C2—C21	127.73 (16)	H51A—C51—H51B	109.5
C2—C21—H21A	109.5	C5—C51—H51C	109.5
C2—C21—H21B	109.5	H51A—C51—H51C	109.5
H21A—C21—H21B	109.5	H51B—C51—H51C	109.5
C2—C21—H21C	109.5	C7—C6—C5	120.49 (16)
H21A—C21—H21C	109.5	C7—C6—H6	119.8
H21B—C21—H21C	109.5	C5—C6—H6	119.8
C3A—C3—C2	105.24 (15)	N7—C7—N7A	117.38 (15)
C3A—C3—H3	127.4	N7—C7—C6	127.60 (16)
C2—C3—H3	127.4	N7A—C7—C6	115.02 (15)
N4—C3A—N7A	121.62 (15)	C7—N7—H7A	120.0
N4—C3A—C3	133.03 (16)	C7—N7—H7B	120.0
N7A—C3A—C3	105.35 (15)	H7A—N7—H7B	120.0
C5—N4—C3A	116.61 (14)	N1—N7A—C7	124.31 (14)
N4—C5—C6	123.51 (16)	N1—N7A—C3A	112.97 (13)
N4—C5—C51	117.00 (16)	C7—N7A—C3A	122.72 (15)

N7A—N1—C2—C3	−0.2 (2)	C5—C6—C7—N7	−177.84 (18)
N7A—N1—C2—C21	−179.70 (17)	C5—C6—C7—N7A	1.7 (3)
N1—C2—C3—C3A	0.6 (2)	C2—N1—N7A—C7	179.03 (15)
C21—C2—C3—C3A	−179.95 (19)	C2—N1—N7A—C3A	−0.32 (19)
C2—C3—C3A—N4	−179.99 (19)	N7—C7—N7A—N1	−1.5 (2)
C2—C3—C3A—N7A	−0.7 (2)	C6—C7—N7A—N1	178.83 (16)
N7A—C3A—N4—C5	0.7 (2)	N7—C7—N7A—C3A	177.76 (17)
C3—C3A—N4—C5	179.9 (2)	C6—C7—N7A—C3A	−1.9 (2)
C3A—N4—C5—C6	−0.8 (3)	N4—C3A—N7A—N1	−179.95 (15)
C3A—N4—C5—C51	179.48 (17)	C3—C3A—N7A—N1	0.7 (2)
N4—C5—C6—C7	−0.4 (3)	N4—C3A—N7A—C7	0.7 (3)
C51—C5—C6—C7	179.24 (19)	C3—C3A—N7A—C7	−178.70 (16)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N4	0.96	1.81	2.763 (2)	172
N7—H7A···N1ⁱ	0.88	2.21	2.971 (2)	144
N7—H7B···O1ⁱⁱ	0.88	2.01	2.877 (2)	168

Symmetry codes: (i) −x+2, y, −z+2; (ii) x+1/2, y−1/2, z.

Experimental details

Crystal data
Chemical formula	C₈H₁₀N₄·0.5H₂O
M_r	171.21
Crystal system, space group	Monoclinic, C2
Temperature (K)	120
a, b, c (Å)	16.0851 (5), 7.9458 (3), 8.0003 (3)
β (°)	117.309 (2)
V (Å³)	908.55 (6)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.54 × 0.36 × 0.20

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2003)
T_min, T_max	0.967, 0.983
No. of measured, independent and observed [I > 2σ(I)] reflections	6163, 1116, 1032
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.090, 1.06
No. of reflections	1116
No. of parameters	116
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.17, −0.20

Computer programs: COLLECT (Hooft, 1999), DENZO (Otwinowski & Minor, 1997) and COLLECT, DENZO and COLLECT, OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997), OSCAIL and SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003), SHELXL97 and PRPKAPPA (Ferguson, 1999).

Selected geometric parameters (Å, º) top

N1—C2	1.342 (2)	C6—C7	1.390 (2)
C2—C3	1.401 (3)	C7—N7A	1.371 (2)
C3—C3A	1.392 (3)	N7A—N1	1.368 (2)
C3A—N4	1.355 (2)	C3A—N7A	1.384 (2)
N4—C5	1.332 (2)	C7—N7	1.333 (2)
C5—C6	1.393 (3)

N7—C7—N7A	117.38 (15)	N7—C7—C6	127.60 (16)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N4	0.96	1.81	2.763 (2)	172
N7—H7A···N1ⁱ	0.88	2.21	2.971 (2)	144
N7—H7B···O1ⁱⁱ	0.88	2.01	2.877 (2)	168

Symmetry codes: (i) −x+2, y, −z+2; (ii) x+1/2, y−1/2, z.

Acknowledgements

X-ray data were collected at the EPSRC X-ray Crystallographic Service, University of Southampton, England. JC thanks the Consejería de Innovación, Ciencia y Empresa (Junta de Andalucía, Spain) and the Universidad de Jaén for financial support. JP and JQ thank COLCIENCIAS and UNIVALLE (Universidad del Valle, Colombia) for financial support.

References

Al-Shiekh, M., Salah El-Din, A. M., Hafez, E. & Elnagdi, M. H. (2004). J. Heterocycl. Chem. 41, 647–654. CAS Google Scholar
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Volume 62| Part 4| April 2006| Pages o186-o189

doi:10.1107/S0108270106005373

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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

7-Amino-2,5-di­methyl­pyrazolo[1,5-a]pyrimidine hemihydrate redetermined at 120 K: a three-dimensional hydrogen-bonded framework

Comment

Experimental

Crystal data

Data collection

Refinement

Supporting information

Acknowledgements

References

organic compounds

7-Amino-2,5-dimethylpyrazolo[1,5-a]pyrimidine hemihydrate redetermined at 120 K: a three-dimensional hydrogen-bonded framework