Methanol-Influenced Assembly of Metal–Organic Hybrid Compounds Based on Propane-1,3-diamine Ligands and [XCl4]2– (X = Zn, Hg)

Abstract

The authors designed two flexible ligand molecules, namely, (N1,N1,N3,N3-tetrakis(4-methylbenzyl)propane-1,3-diamine) (L1) and (N1,N1,N3,N3-tetrabenzylpropane-1,3-diamine) (L2), with (CH2)3 alkyl chains attached to the two N atoms. The ligands are double protonated and can react with tetrachloride metal dianion [XCl4]2– (X = Zn, Hg) in the presence of methanol solvent, leading to a series of new inclusion complexes, (CH3OH)2 ⊂ [L1]2H+· [ZnCl4]2–(crystal 1), (CH3OH)0.5 ⊂ [L2]2H+·[HgCl4]2 (crystal 2), and CH3OH ⊂ {[L2]2H+}0.5· {[ZnCl4]2–}0.5 (crystal 3). The molar ratios of methanol and ligand are 2:1, 1:2, and 2:1 in the three crystals, respectively. The structures were characterized by NMR and single-crystal X-ray diffractions. The effect of guest methanol molecules on the formation of supramolecular assemblies was discussed. The ligand can adopt different molecular arrangements as so to suit for the demands of same guest species. From the structural view point, we showed the relationship between the diversity of inclusion hosts and conformational flexibility of ligand.