Crystal and molecular structure of the quinuclidine betaine with p-hydroxybenzoic acid complex studied by X-ray diffraction, DFT, FTIR, and NMR methods

✍ Scribed by Z. Dega-Szafran; A. Katrusiak; M. Szafran

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 952 KB
• Volume: 967
• Category: Article
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2009.12.043

✦ Synopsis

Quinuclidine betaine (1-carboxymethyl-1-azabicyclo[2.2.2]octane inner salt, QNB) forms a complex with p-hydroxybenzoic acid (HBA) at the 1:1 ratio. The crystals are triclinic, space group P 1, with two symmetry non-equivalent QNBÁHBA complexes linked by a sequence of four O-HÁÁÁO hydrogen bonds into a zigzag chain. Both oxygen atoms of the carboxylate groups of two QNB are linked with two HBA molecules through the COOÁÁÁHOOC hydrogen bonds of 2.561(2), and 2.556(2) Å, and the COOÁÁÁHO hydrogen bonds of 2.609(2) and 2.687(2) Å. A trio ABC band at ca. 2800, 2550, 1910 cm À1 observed in the FTIR spectrum is characteristic of a medium-strong hydrogen bond in carboxylic acids. The second-derivative IR spectrum confirms the presence of two non-equivalent C@O and two COO groups. The molecular structures of the 1:1 and 2:2 complexes have been optimized by the B3LYP/6-31G(d,p) approach. The experimental and predicted, by GIAO/B3LYP/6-31G(d,p), 1 H and 13 C chemical shifts correlate linearly.