Structural, spectral and thermal properties of 2,2’-iminodipyridinium(+) trihydrogen pyromellitate

Abstract

The title compound, (Hdipya)(H3pyr), where Hdipya is protonated 2,2?-dipyridilamine and H3pyr is monoanion of pyromellytic acid (H4pyr), was obtained from the reaction mixture containing Zn(II) ions, dipya, Na4pyr (the molar ratio 2 : 2 : 1) and HNO3. The products (micro- and single-crystalline) were characterized by X-ray structure determination, FT-IR spectroscopy and TG/DSC analysis. The most striking structural feature of (Hdipya)(H3pyr) are short inter- and extremely short intramolecular hydrogen bonds. These bonds mutually connect cations and anions making thin layers parallel to the crystallographic (223) plane. Also, quite unusual, linear proton-bound polymeric {H(H2pyr)-}n anions were identified in the structure. The results of crystal structure determination are compared with FT-IR and TG/DSC data. The low position of nas(COO) vibration at 1660 cm-1 is in accordance with strong hydrogen bonding. This value can be used as a measure of C=O bond order, which is calculated to be 1.81.