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2,6-Di­amino­pyridine (26-DAP, C5H7N3) is a common inter­mediate in the synthesis of aromatic azo chromophores, which are widespread in the dyes and pigments industry. Sublimation of commercial 26-DAP powder yielded a new polymorph, denoted Form II, which grew as colorless ortho­rhom­bic needles. Recrystallization from acetone or toluene also yielded Form II as the major phase. Thermal analysis shows that Form II is a less stable polymorph and it converts upon heating at 335 K to the previously reported Form I.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2053229617014978/qs3064sup1.cif
Contains datablock I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S2053229617014978/qs3064Isup2.hkl
Contains datablock I

cml

Chemical Markup Language (CML) file https://doi.org/10.1107/S2053229617014978/qs3064Isup3.cml
Supplementary material

CCDC reference: 1580103

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014), XPREP (Bruker, 2014) and SADABS (Bruker, 2014); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: SHELXTL (Bruker, 2014); software used to prepare material for publication: XCIF (Bruker, 2014).

Pyridine-2,6-diamine top
Crystal data top
C5H7N3Dx = 1.313 Mg m3
Mr = 109.14Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, PbcaCell parameters from 10034 reflections
a = 5.1217 (9) Åθ = 3.7–19.6°
b = 9.8397 (14) ŵ = 0.09 mm1
c = 21.914 (4) ÅT = 100 K
V = 1104.4 (3) Å3Needle, colorless
Z = 80.44 × 0.05 × 0.02 mm
F(000) = 464
Data collection top
Bruker APEX DUO/APEXII CCD
diffractometer
948 independent reflections
Radiation source: fine-focus sealed tube559 reflections with I > 2σ(I)
Multilayer mirrors monochromatorRint = 0.180
profile data from φ and ω scansθmax = 24.9°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Bruker, 2014)
h = 66
Tmin = 0.518, Tmax = 0.745k = 1111
8750 measured reflectionsl = 2525
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.056 w = 1/[σ2(Fo2) + (0.0763P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.149(Δ/σ)max < 0.001
S = 0.98Δρmax = 0.32 e Å3
948 reflectionsΔρmin = 0.24 e Å3
86 parametersExtinction correction: SHELXL2014 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
4 restraintsExtinction coefficient: 0.018 (4)
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N10.0267 (5)0.6215 (2)0.18272 (11)0.0207 (7)
N20.3151 (5)0.4730 (3)0.17132 (13)0.0272 (8)
H2A0.460 (5)0.456 (4)0.1506 (14)0.041*
H2B0.343 (7)0.487 (4)0.2108 (9)0.041*
N30.3660 (6)0.7692 (3)0.20060 (12)0.0237 (7)
H3A0.399 (7)0.730 (3)0.2371 (10)0.036*
H3B0.511 (5)0.806 (3)0.1854 (15)0.036*
C10.1445 (6)0.5638 (3)0.14421 (14)0.0231 (8)
C20.1450 (7)0.5874 (3)0.08154 (14)0.0298 (9)
H20.26790.54420.05550.036*
C30.0409 (7)0.6765 (4)0.05851 (16)0.0333 (10)
H30.04740.69480.01600.040*
C40.2160 (6)0.7385 (3)0.09735 (14)0.0257 (8)
H40.34180.80070.08200.031*
C50.2056 (6)0.7086 (3)0.15879 (13)0.0201 (8)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0239 (15)0.0110 (13)0.0272 (15)0.0011 (12)0.0006 (12)0.0004 (11)
N20.0247 (17)0.0129 (14)0.0440 (18)0.0037 (13)0.0045 (14)0.0018 (12)
N30.0268 (16)0.0154 (15)0.0289 (16)0.0050 (13)0.0012 (14)0.0028 (11)
C10.0240 (18)0.0096 (16)0.0358 (18)0.0068 (14)0.0018 (16)0.0022 (13)
C20.032 (2)0.025 (2)0.0318 (19)0.0052 (17)0.0055 (17)0.0057 (13)
C30.038 (2)0.036 (2)0.0258 (19)0.0085 (18)0.0016 (17)0.0043 (15)
C40.0289 (19)0.0192 (18)0.0290 (18)0.0016 (16)0.0001 (15)0.0033 (13)
C50.0222 (18)0.0103 (16)0.0279 (18)0.0058 (14)0.0010 (14)0.0014 (12)
Geometric parameters (Å, º) top
N1—C11.343 (4)C1—C21.393 (4)
N1—C51.360 (4)C2—C31.389 (5)
N2—C11.384 (4)C2—H20.9500
N2—H2A0.886 (18)C3—C41.378 (5)
N2—H2B0.888 (18)C3—H30.9500
N3—C51.368 (4)C4—C51.379 (4)
N3—H3A0.902 (18)C4—H40.9500
N3—H3B0.891 (18)
C1—N1—C5117.6 (3)C3—C2—H2121.2
C1—N2—H2A115 (2)C1—C2—H2121.2
C1—N2—H2B115 (2)C4—C3—C2120.0 (3)
H2A—N2—H2B113 (3)C4—C3—H3120.0
C5—N3—H3A121 (2)C2—C3—H3120.0
C5—N3—H3B115 (2)C3—C4—C5118.9 (3)
H3A—N3—H3B110 (3)C3—C4—H4120.5
N1—C1—N2114.5 (3)C5—C4—H4120.5
N1—C1—C2123.4 (3)N1—C5—N3114.9 (3)
N2—C1—C2122.0 (3)N1—C5—C4122.5 (3)
C3—C2—C1117.5 (3)N3—C5—C4122.6 (3)
C5—N1—C1—N2178.0 (3)C2—C3—C4—C51.1 (5)
C5—N1—C1—C20.9 (4)C1—N1—C5—N3176.9 (3)
N1—C1—C2—C30.7 (5)C1—N1—C5—C40.2 (4)
N2—C1—C2—C3177.5 (3)C3—C4—C5—N10.8 (5)
C1—C2—C3—C40.4 (5)C3—C4—C5—N3177.7 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3A···N1i0.90 (2)2.16 (2)3.054 (4)171 (3)
N3—H3B···N2ii0.89 (2)2.29 (2)3.118 (4)155 (3)
Symmetry codes: (i) x+1/2, y, z+1/2; (ii) x+1/2, y+1/2, z.
 

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