Hydrogen Bonding in Acid Li-, Ni-, Tetrabutylammonium, and Ammonium Salts of Benzene-1,2,4,5-tetracarboxylic Acid (Pyromellitic Acid)

Hydrogen-bonding behaviour of benzene-1,2,4,5-tetracarboxylic acid: supramolecular structures of different dimensionality in the 2:1 adducts formed with 4,4′-bipyridyl and hexamethylenetetramine

“…9). An anion (C 10 H 4 O 8 ) 2À of similar type to those found in (2) and in TEKLOK has also been observed in the [{Ni(H 2 O) 6 } 2+ ] salt (PAHXIF;Jessen et al, 1992). This salt crystallizes in the rare (Brock & Dunitz, 1994) space group P2/m and the anions are located at sites of 2/m (C2 h ) symmetry.…”

“…In contrast to these analogues of the (C 10 H 4 O 8 ) 2À anions in (2), the conformation of the anion in (1) is closely mimicked by that in the ammonium salt [(NH 4 ) + ] 2 Á[(C 10 H 4 O 8 ) 2À ] (3) (PAHXOL; Jessen et al, 1992), where, as in (1), no intramolecular OÐHÁ Á ÁO hydrogen bonds are found. The overall supramolecular structure is three-dimensional, with the ammonium ions forming one NÐHÁ Á ÁO hydrogen bond to each of four different anions disposed approximately tetrahedrally about the cation.…”

“…It is noteworthy that in (1) it is two of the CÐH bonds in the protonated pyridyl ring which participate in CÐ HÁ Á ÁO hydrogen bonds, while in (2) interactions of this type are formed only by CÐH bonds adjacent to the protonated N atoms N41 and N51. In both structures, therefore, the ionic nature of Part of the crystal structure of [(NH 4 ) + ] 2 Á[(C 10 H 4 O 8 ) 2À ] (Jessen et al, 1992) showing a twodimensional R 4 4 (28) net built from anions only. H atoms bonded to C are omitted for the sake of clarity; the atom marked with a star (*) is at the symmetry position (1 À xY À 1 2 yY 3 2 À z).…”

Hydrogen Bonding in the 2,2'-Bipyridinium Salt of 1,2,4,5-Benzenetetracarboxylic Acid (Pyromellitic Acid)

“…1) and H(O1)...O7 i 2.636 (2)A hydrogen bonds [symmetry code: (i) 1-x, 2-y, -z]. The bond distances in the neutral PMA molecule and the PMA 2-anion are consistent with those usually found (Jessen, Kiippers & Luehrs, 1992). The structure of the pyromellitate anion differs from that of the neutral acid.…”

Structural studies and conductivity of [Fe(O<sub>3</sub>C<sub>4</sub>)(COO)]·H<sub>2</sub>O based H<sub>4</sub>btec (H<sub>4</sub>btec = 1,2,4,5-benzenetetracarboxylic acid)

“…In spite of the rich coordination chemistry exhibited by H 2 bdc and H 3 btc (Chart 1) in the presence of auxiliary ligands and coordinated solvents, barring a few sporadic reports, which mainly concentrate on the direct interaction between the metal ion and the ligand, there have been no serious attempts to prepare metal-organic polymeric or supramolecular structures based on 1,2,4,5benzene tetracarboxylic acid (H 4 btec) [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]. It may be argued that, due to steric reasons, all the four carboxyl groups of H 4 btec are unlikely to take part in coordination to the metal.…”