The Synthesis and Characterization of 2-Amino-3-methylpyridinium Dihydrogenmonophosphate: (C₆H₉N₂)H₂PO₄

Abstract

A new crystal of 2-amino-3-methylpyridinium dihydrogenmonophosphate has been prepared and characterized by X-ray crystallography, thermal analysis, and impedance and NMR spectroscopies. This compound crystallizes in the triclinic space group P with a = 7.343(2) Å, b = 7.987(2) Å, c = 8.116(4) Å, α = 77,62(3)°, β = 77,74(3)°, γ = 87,03(2)°, V = 454.3 (3)ų, and Z = 2. The crystal structure was solved and refined to R = 0.030 with 1602 independent reflections. The atomic arrangement can be described as (H₂PO₄ ⁻)_n polymeric chains anchoring the 2-amino-3-methylpyridinium cations through short hydrogen bonds. All ring atoms of the organic entity are coplanar. The exocyclic N atom is an electron receiving center, which is consistent with features of imino resonance evidenced by bond lengths and angles. Solid state ³¹P, ¹³C, and ¹⁵N CP-MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of carbons and nitrogen to the independent crystallographic sites.

Keywords:

• Crystal structure
• dihydrogenomonophosphate
• impedance spectroscopy
• nuclear magnetic resonance
• X-ray diffraction

Notes

(*)Theoretical chemical shift determined by calibrating the peak of the methyl carbon atom at 15.6 ppm.