One-dimensional hydrogen-bonded structures in the 1:1 proton-transfer salts of 4,5-dichlorophthalic acid with the aliphatic lewis bases diisopropylamine and hexamethylenetetramine

Article abstract of DOI:10.1007/s10870-009-9636-7

The crystal structures of the 1:1 proton-transfer compounds of 4,5-dichlorophthalic acid with the aliphatic Lewis bases diisopropylamine and hexamethylenetetramine, viz. diisopropylaminium 2-carboxy-4,5-dichlorobenzoate (1) and hexamethylenetetraminium 2-carboxy-4,5-dichlorobenzoate hemihydrate (2), have been determined. Crystals of both 1 and 2 are triclinic, space group P - 1, with Z = 2 in cells with a = 7.0299(5), b = 9.4712(7), c = 12.790(1) A, α = 99.476(6), β = 100.843(6), γ = 97.578(6)° (1) and a = 7.5624(8), b = 9.8918(8), c = 11.5881(16) A, α = 65.660(6), β = 86.583(4), γ = 86.987(8)° (2). In each, one-dimensional hydrogen-bonded chain structures are found: in 1 formed through aminium N ⁺-H...O_carboxyl cation-anion interactions. In 2, the chains are formed through anion carboxyl O???H-O _{bridging water} interactions with the cations peripherally bound. In both structures, the hydrogen phthalate anions are essentially planar with short intra-species carboxylic acid O-H...O_carboxyl hydrogen bonds [O...O, 2.381(3) A (1) and 2.381(8) A (2)].