Crystal structure, Hirshfeld surface analysis and energy framework calculations of different metal complexes of a biphenol-based ligand: Role of solvent and transition metal ion

A new Pd(II) complex of the previously reported ligand N,N '-bis[(2,2 '-dihydroxybiphen-3-yl)methyl]-N,N ' dimethylethylenediamine (L) was obtained from N,N-dimethylformamide/water. The roles in the solid state assembly of solvent molecules and molecular conformation were studied by comparing six complexes of L containing different metal centers (Ni(II), Cd(II), Cu(II), Pd(II)). Hirshfeld surface analysis, 2D fingerprint plots and energy frameworks calculations were used to investigate the intermolecular interactions within the crystal packings. Pd(II) and Ni(II) complexes arrange to form ribbons, while Cd(II) and Cu(II) complexes form 3D networks. Interactions between complexes and solvent molecules in the previously reported Pd(II) complex are replaced by complex-complex interactions in the new Pd(II) complex, while butanol and methanol are interchangeable in the interactions within the Ni(II) complexes. The present study suggested that the solid state assembly of these systems is mainly driven by the molecular conformation, that depends in turn by the metal ion involved, while the solvent only plays a minor role.