Influence of the position of methoxy group of β-diketone ligand on structural conformation and supramolecular features of mononuclear cu(II) complex

In this study, a new pentavalent mono-nuclear copper complex with chelating bidentate ethyl 4-(4-methoxyphenyl)-2,4-dioxobutanoate ligand (p-OCH₃-L) has been synthesized via condensation reaction and the structure was confirmed by single crystal X-ray diffraction studies. The effect of the position of the methoxy group of β-diketone ligands on the coordination complex was explored by comparison of structural and supramolecular conformation of new complex-1 [Cu(p-OCH₃-L)₂.H₂O] with the complex-2 [Cu(m-OCH₃-L)₂. H₂O] was taken from CSD database. The interaction of hydrogen bonding contacts in complex 1 forms a three-dimensional supramolecular assembly with zig-zag and ladder-like architecture. While in complex 2, an infinite linear 2-D sheet molecular assembly is observed. The planar structure of a molecule plays a crucial role in enhancing stacking interactions, which can be quantitatively assessed through enrichment ratio analysis. Experimental data and theoretical calculations reveal that the steric and electronic factors introduced by the para- and meta-methoxy groups within the coordinating β-diketone moieties have minimal impact on the electronic properties. However, these factors significantly influence the structural conformation and supramolecular packing of the complexes.