Supramolecular Self-Assembly of M-IDA Complexes Involving Lone-Pair•••π Interactions: Crystal Structures, Hirshfeld Surface Analysis, and DFT Calculations [H2IDA = iminodiacetic acid, M = Cu(II), Ni(II)]

Mononuclear copper(II) and nickel(II) complexes, [(C5H6N2)Cu(IDA) (H2O)] (1) and (C5H7N2)(2)[Ni(IDA)(2)(H2O)] (2) [H(2)IDA = iminodiacetic acid; C5H6N2 = 4-aminopyridine; C5H7N2 = protonated 2-aminopyridine], have been synthesized, and their crystal structures were solved using single crystal X-ray diffraction data. A detailed analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions, which are crucial in building different supramolecular architectures. Molecules are linked by a combination of N-H center dot center dot center dot O, O-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds into two-dimensional framework, whose formation is readily analyzed in terms of substructures of lower dimensionality with zero finite zero-dimensional dimeric units as the building blocks within the structures. Moreover, the aromatic molecules that are engaged in lone pair center dot center dot center dot pi interactions with he noncoordinated carbonyl moieties play a crucial role in stabilzing the self-assembly process observed for both complexes. Intricate combinations of hydrogen bonding, lone pair center dot center dot center dot pi and pi-pi interactions are fully described along with the computational studies.