Multi-component supramolecular compounds containing hexaamminecobalt(iii) cations and aromatic sulfonic acid derivatives

Abstract

A series of new multi-component supramolecular compounds containing [Co(NH₃)₆]³⁺ cations and aromatic sulfonic acid derivatives has been synthesized and characterized using elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffraction. The series includes [Co(NH₃)₆](pys)₃·Hpys (1), [Co(NH₃)₆](pys)₂Cl·2MeCN (2), [Co(NH₃)₆](3-sb)Cl·4H₂O (3), [Co(NH₃)₆]₂(3-sb)(SO₄)Cl₂·7H₂O (4), {[Co(NH₃)₆][Na(3-sb)Cl₂]·H₂O}_n (5), {[Co(NH₃)₆][K₂(4-sb)₂Cl]}_n (6), and [Co(NH₃)₆](Hssz)(ssz)·4H₂O (7) (where Hpys = 3-pyridinesulfonic acid, H₂sb = 3-/4-sulfobenzoic acid, H₂ssz = sulfasalazine). Single-crystal X-ray diffraction analysis reveals that the compounds are ionic and multi-component, with complex [Co(NH₃)₆]³⁺ cations forming hydrogen bonds with anions and solvate molecules. The presence of alkali metal cations in the crystals of 5 and 6 leads to the formation of anionic coordination polymers, 1D in 5 and 3D in 6, which are H-bonded to complex [Co(NH₃)₆]³⁺ cations. Hirshfeld surface analysis and 2D fingerprint plots demonstrate that the hexaamminecobalt(III) cation exhibits significant hydrogen bond capability when co-crystallized with derivatives of sulfonic acid, and in addition to hydrogen bonds of N–H⋯O type between the amine ligands and the sulfonate groups, π⋯π stacking and C−H⋯π interactions contribute significantly in stabilizing the supramolecular architectures. Energy decomposition analysis of the intermolecular interaction energy was performed using the SAPT method to study the non-covalent bonding interactions of [Co(NH₃)₆]³⁺ cations with various aromatic sulfonic acid derivatives in 1–7.