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, [(C 5 H 6 N 2 )Cu(IDA)(H 2 O)] ( 1 ) and (C 5 H 7 N 2 ) 2 [Ni(IDA) 2 (H 2 O)] ( 2 ) [H 2 IDA = iminodiacetic acid; C 5 H 6 N 2 = 4-aminopyridine; C 5 H 7 N 2 = 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···O, O–H···O and C–H···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···π interactions with the noncoordinated carbonyl moieties play a crucial role in stabilizing the self-assembly process observed for both complexes. Intricate combinations of hydrogen bonding, lone pair···π and π–π interactions are fully described along with the computational studies.