Supramolecular architectures of Mn(NCS)2 complexes with N'-(1-(pyridin-4-yl)ethylidene)picolinohydrazide and N'-(phenyl(pyridin-4-yl)methylene)isonicotinohydrazide

Abstract

In this work we have synthesized and characterized new mononuclear heteroleptic discrete complexes [Mn(NCS)2(HLI)2(MeOH)2] (1), [Mn(NCS)2(HLI)2(EtOH)2] (2) and [Mn(NCS)2(HLII)2(EtOH)2] (3), fabricated from Mn(NCS)2 and N'-(1-(pyridin-4-yl)ethylidene)picolinohydrazide (HLI) and N'-(phenyl(pyridin-4-yl)methylene)isonicotinohydrazide (HLII) in MeOH or EtOH. All the obtained complexes are structurally similar, while complexes 1 and 2 are isostructural. The metal center in all the structures is six-coordinated and in a N4O2 geometry, formed by two monodentate ligands HLI or HLII, each exclusively linked through the 4-pyridil nitrogen atom, two N-coordinated NCS− anions and two O-coordinated molecules of MeOH or EtOH. Crystal packing of 1 and 2 are mainly dictated by the intermolecular OH∙∙∙O hydrogen bonds, while the crystal packing of 3 is mainly driven by the intermolecular OH∙∙∙N hydrogen bonds. The structures of 1–3 reveal the uninodal 1D chains with the 2C1 topology, when complex molecules are considered as a node and OH∙∙∙O (in 1 and 2) of OH∙∙∙N (in 3) hydrogen bonds are considered. Considering remaining non-covalent interactions, the resulting topology can be extended up to a four-connected uninodal sql (Shubnikov tetragonal plane net) topology. The multilevel topological description of the molecular packing of 1–3, when all van der Waals interactions are considered, reveal that the structures of 1 and 2 are assembled from a linear chain through square lattice to different 3D frameworks, while the structure of 3, although starts from the same linear chain, produces 3D frameworks skipping 2D topologies. Molecular surfaces of 1–3 are mainly described by intermolecular H∙∙∙H, H∙∙∙C, H∙∙∙N, H∙∙∙O and H∙∙∙S contacts. Self-assembled supramolecular dimers observed in the solid state of all compounds have been studied using density functional theory (DFT) calculations, molecular electrostatic potential (MEP) surfaces and the NCIplot index. Moreover, the interaction energy of each individual hydrogen bond has been estimated using the quantum theory of «atoms-in-molecules» (QTAIM).