The co-crystal of iron(II) complex hydrate with hydroxybenzoic acid: [Fe(Phen)3]Cl(p-hydroxybenzoate).2(p-hydroxybenzoic acid).7H2O

Abstract

Crystal of [Fe(Phen)3]Cl(PHB).2(PHBH).7H2O (1) is triclinic, space group P-1 with a = 12.0388(11) A, b = 15.5286(14) A, c = 15.7794(14) A, α = 89.759(2)°, β = 75.818(2)°, γ = 71.900(2)° and Z = 2, (phen = phenanthroline, PHBH = p-hydroxybenzoic acid, PHB = p-hydroxybenzoate anion). The phen in adjacent Fe(phen)3 2+ cations are π–π interacted forming offset face to face (OFF) motifs. Juxtaposition of four phen ligands from two cations encapsulate an R2 2(8) dimeric unit of H-bonded PHBH molecules within a centrosymmetric box froming a filled aryl box motif (FAB). Alternation of OFF and FAB motifs form {OFF⋯FAB}∞ strands. The Fe(phen)3 2+ cation engages its phen ligands in π–π and/or CH–π interactions with two crystalographically different PHBH molecules and one PHB anion. Seven water molecules and a chloride anion per iron(II) trisphenanthroline cation fill empty spaces in the structure forming a hydrophilic cluster. Extensive intermolecular H-bond interactions occur between water molecules, chloride anions, PHBH molecules, and PHB anions. Thermal analysis of (1) was done under N2(g). The TG, and dTG curves revealed the expected mass losses. All associated processes are endothermic as shown in the DSC curve.