Network formation of mellitate anions ([C6(COO)6H6−n]n−) in the salts with piperidinium derivatives and o-phenylenediammonium

Abstract

Single crystals of mellitate anion ([C₆(COO)₆H_6−n]ⁿ⁻) with piperidinium [C₅H₁₀NH₂⁺]₃[C₆(COO)₆H₃³⁻] (1) and [C₅H₁₀NH₂⁺]₂[C₆(COO)₆H₄²⁻]·CH₃OH·3H₂O (2), with 1-methylpiperidinium [C₅H₁₀NHCH₃⁺]₂[C₆(COO)₆H₄²⁻]·2H₂O (3), and with o-phenylenediammonium [C₆H₄(NH₃)₂²⁺]₂[C₆(COO)₆H₂⁴⁻]·2CH₃OH (4) have been prepared and structurally characterized. In all of the salts, two-dimensional (2D) networks of mellitate anions were formed due to the strong self-organization of the anion. In 1, a 2D hexagon-type network of hydrogen-bond has been observed to form among the anions. This is characteristic of the mellitate anions with n = 3 (n: deprotonation number from the acid). In other salts, a 2D anion network containing either water molecules or –NH₃ groups commonly formed. Since the network pattern occurs with different cation species, this hydrogen-bonding unit was determined to be dominant in the n = 2 anion with water and the n = 4 anion with –NH₃ species.