Crystal Structure Determination of Salts Obtained from Cocrystallization of 2,6-Dinitrobenzoic with 2,2′-Bipyridine and 4,4′-Bipyridine

Abstract

The 2:1 cocrystallization of 2,6-dinitrobenzoic acid [LH] with 2,2′-bipyridine [2,2′-bpy] yields a salt cocrystal with formula [2,2′-bpyH][LH][L] which features a three component aggregate where the L⁽⁻⁾ anion bridges [2,2′-bpyH]⁽⁺⁾ and neutral LH via N–H···O and O–H···O hydrogen bonds, respectively. The analogous experiment with 4,4′-bipyridine [4,4′-bpy] produced [4,4′-bpyH₂][L]₂, which also features a three component aggregate but with twofold symmetry and sustained by N–H···O hydrogen bonds. Compound 1 crystallizes in the monoclinic space group P2₁/c with a = 7.707(4) Å, b = 20.966(10) Å, c = 15.267(7) Å, β = 96.259 (10), and Z = 4. Compound 2 crystallizes in the monoclinic space group C2/c with a = 13.552(5) Å, b = 11.299(4) Å, c = 15.858 (6) Å, β = 102.036(7) and Z = 4.

Graphical Abstract

The 2:1 cocrystallization of 2,6-dinitrobenzoic acid with each of 2,2′-bipyridine and 4,4′-bipyridine yields molecules of the same empirical formulae but very different crystal structures.