Tetrabutylammonium hydrogen bisbenzoate: crystal structure and study of short hydrogen bonds in hydrogen bisbenzoate anion system
Tetrabutylammonium hydrogen bisbenzoate (bioxyanion) is a useful nucleophile, soluble in organic solvents and capable of catalysing the silylketene acetal initiated group transfer polymerisation of alkylacrylate monomers, as well as a carbonate interchange reaction of aromatic biphenols with diphenyl carbonate. Tetrabutylammonium hydrogen bisbenzoate has been characterised by 1H and 13C NMR as well as FTIR spectroscopy and compared with its acid and corresponding salts. The structure of [N(Bu)4]+[(PhCOO)2H]– was determined by single crystal X-ray diffraction. Crystals of C30H47NO4 are orthorhombic, space group Pccn with a= 13.038(1), b= 13.589(1), c= 17.124(3)Å and Z= 4. Half of each cation and anion is related to the other half by a two fold axis parallel to the c axis and nitrogen atoms as well as hydrogen atoms of the O ⋯ H ⋯ O group being placed on the two-fold axis. Two benzoate residues in the anion are linked through a short crystallographically symmetrical O ⋯ H ⋯ O hydrogen bond with O ⋯ O distance of 2.459(3)Å. Bifurcated C–H ⋯ O hydrogen bonds from oxygen of the carbonyls connect the cations and anions to form infinite chain networks in the crystal.