Hydrogen Bond, pi-pi, and CH-pi Interactions Governing the Supramolecular Assembly of Some Hydrazone Ligands and Their Mn-II Complexes - Structural and Theoretical Interpretation

摘要

The hydrazone Schiff base ligands (E)-N-(2-hydroxybenzylidene)acetohydrazide (HL1) and (E)-N-(2,3-dihydroxybenzylidene)acetohydrazide (H2L2) with a functional group variation in the aromatic moiety have been synthesized. The ligands have been used to synthesize the following Mn-II complexes: the mononuclear complex [Mn(HL1)(2)][ClO4](2)2H(2)O (1), the cocrystallized discrete dinuclear complex {[Mn(HL1)(2)][Mn(L-1)(2)]}[ClO4](2) (2), and the phenoxido-bridged dinuclear complex [Mn(-HL2)(H2O)](2)[ClO4](2) (3). The ligands and the complexes were characterized by FTIR and UV/Vis spectroscopic techniques, and their crystal structures were determined by single-crystal X-ray diffraction analysis. H-1 and C-13 NMR spectroscopy shows evidence of keto-enol tautomerism of the ligands in solution. All of the compounds develop hydrogen-bonded assemblies of different dimensionalities and architectures. CH- and - interactions also contribute significantly to the overall binding energies of the supramolecular assemblies. The supramolecular interaction energies have been computed at the BP86-D3/def2-TZVPD level of theory.