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BY 4.0 license Open Access Published by De Gruyter (O) August 2, 2021

The crystal structure of 6-amino-2-carboxypyridin-1-ium bromide, C6H7BrN2O2

Mengbing Cui ORCID logo, Yan Zeng ORCID logo, Yong Li and Heng Chen

Abstract

C6H7BrN2O2, monoclinic, C2/c (no. 15), a = 23.7470(19) Å, b = 5.4355(4) Å, c = 15.3336(11) Å, β = 127.291(2)°, V = 1574.6(2) Å3, Z = 8, R gt(F) = 0.0292, wR ref(F 2) = 0.0756, T = 150(2) K.

CCDC no.: 2096418

The molecular structure is shown in the figure. Table 1 contains crystallographic data and Table 2 contains the list of the atoms including atomic coordinates and displacement parameters.

Table 1:

Data collection and handling.

Crystal: Colorless block
Size: 0.20 × 0.15 × 0.10 mm
Wavelength: Mo Kα radiation (0.71073 Å)
μ: 5.17 mm−1
Diffractometer, scan mode: Bruker APEX-II, φ and ω
θ max, completeness: 26.4°, >99%
N(hkl)measured, N(hkl)unique, R int: 10,308, 1605, 0.065
Criterion for I obs, N(hkl)gt: I obs > 2 σ(I obs), 1263
N(param)refined: 104
Programs: Bruker [1], Olex2 [2], SHELX [3], [4]

Table 2:

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

Atom x y z U iso*/U eq
Br1 0.35629 (2) 0.70045 (7) 0.18186 (3) 0.02907 (13)
C1 0.35421 (19) 0.2212 (7) 0.3494 (3) 0.0250 (8)
C2 0.38342 (19) 0.3998 (7) 0.4415 (3) 0.0242 (8)
C3 0.45042 (19) 0.4028 (7) 0.5351 (3) 0.0263 (8)
H3 0.483723 0.281395 0.548937 0.032*
C4 0.46953 (19) 0.5918 (7) 0.6117 (3) 0.0266 (8)
H4 0.516490 0.598262 0.677762 0.032*
C5 0.4222 (2) 0.7632 (7) 0.5925 (3) 0.0262 (8)
H5 0.436086 0.890552 0.644345 0.031*
C6 0.3517 (2) 0.7534 (6) 0.4950 (3) 0.0245 (8)
H1 0.391 (3) −0.027 (9) 0.325 (4) 0.049(17)*
N1 0.30312 (17) 0.9169 (6) 0.4716 (2) 0.0311 (7)
H1A 0.260270 0.907483 0.409111 0.037*
H1B 0.313628 1.035041 0.518458 0.037*
N2 0.33528 (15) 0.5722 (5) 0.4226 (2) 0.0231 (7)
H2 0.291958 0.564967 0.361020 0.028*
O1 0.40101 (15) 0.0577 (5) 0.3690 (2) 0.0333 (7)
O2 0.29337 (13) 0.2345 (5) 0.26787 (19) 0.0273 (6)

Source of material

All reagents are purchased from TCI Chemicals and used as received. An amount of 1.38 g of 6-aminopicolinic acid (10 mmol) was added to 10 mL concentrated hydrobromic acid (40%) and stirred for 10 min at room temperature, then filtered, left quietly, and evaporated naturally. Several days later, colorless crystals of 6-amino-2-carboxypyridin-1-ium bromide, C6H7BrN2O2 (ACPB) were obtained, yield 58% (based on 6-aminopicolinic acid).

Experimental details

The structure was solved by direct methods with the SHELXS-2018 program. All H-atoms from C and N atoms were positioned with idealized geometry and refined isotropically (U iso(H) = 1.2U eq(C) and U iso(H) = 1.2U eq(N)) using a riding model with C–H = 0.95 Å and N–H = 0.88 Å. The hydrogen atom at O1 was seen in the Fourier difference map and refined with the distance of O2–H2 = 0.84 Å (U iso(H) = 1.5U eq(O)).

Comment

Known as a multi-functional ligand, 6-aminopicolinic acid was used to construct metal complexes or metal-organic frameworks [5], [6], [7], [8], [9]. We here report the crystal structure of the bromide salt of the 6-aminopicolinic acid, ACPB. ACPB crystallizes in monoclinic system, C2/c group (no. 15). The asymmetric unit is composed of one protonated 6-aminopicolinic acid (2-amino-6-carboxypyridin-1-ium cation) and one bromide anion. The 2-amino-6-carboxypyridin-1-ium cations are linked to each other by N–H⋯Br; O–H⋯Br and N–H⋯O hydrogen bonds, respectively. All of the bond lengths of the ACPB are similar to the reported results [].


Corresponding author: Mengbing Cui, School of Pharmacy, Xinxiang University, Xinxiang, Henan 453003, P. R. China, E-mail:

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: None declared.

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.

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Received: 2021-06-20
Accepted: 2021-07-14
Published Online: 2021-08-02
Published in Print: 2021-12-20

© 2021 Mengbing Cui et al., published by De Gruyter, Berlin/Boston

This work is licensed under the Creative Commons Attribution 4.0 International License.