Tetrel Bonding and Other Non-Covalent Interactions Assisted Supramolecular Aggregation in a New Pb(II) Complex of an Isonicotinohydrazide.
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ABSTRACT: A new supramolecular Pb(II) complex [PbL(NO2)]n was synthesized from Pb(NO3)2, N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and NaNO2. [PbL(NO2)]n is constructed from discrete [PbL(NO2)] units with an almost ideal N2O3 square pyramidal coordination environment around Pb(II). The ligand L- is coordinated through the 2-pyridyl N-atom, one aza N-atom, and the carbonyl O-atom. The nitrite ligand binds in a ?2-O,O coordination mode through both O-atoms. The Pb(II) center exhibits a hemidirected coordination geometry with a pronounced coordination gap, which allows a close approach of two additional N-atoms arising from the N=C(O) N-atom of an adjacent molecule and from the 4-pyridyl N-atom from the another adjacent molecule, yielding a N4O3 coordination, constructed from two Pb-N and three Pb-O covalent bonds, and two Pb?N tetrel bonds. Dimeric units in the structure of [PbL(NO2)]n are formed by the Pb?N=C(O) tetrel bonds and intermolecular electrostatically enforced ?+??- stacking interactions between the 2- and 4-pyridyl rings and further stabilized by C-H?? intermolecular interactions, formed by one of the methyl H-atoms and the 4-pyridyl ring. These dimers are embedded in a 2D network representing a simplified uninodal 3-connected fes (Shubnikov plane net) topology defined by the point symbol (4?82). The Hirshfeld surface analysis of [PbL(NO2)] revealed that the intermolecular H?X (X = H, C, N, O) contacts occupy an overwhelming majority of the molecular surface of the [PbL(NO2)] coordination unit. Furthermore, the structure is characterized by intermolecular C?C and C?N interactions, corresponding to the intermolecular ??? stacking interactions. Notably, intermolecular Pb?N and, most interestingly, Pb?H interactions are remarkable contributors to the molecular surface of [PbL(NO2)]. While the former contacts are due to the Pb?N tetrel bonds, the latter contacts are mainly due to the interaction with the methyl H-atoms in the ??? stacked [PbL(NO2)] molecules. Molecular electrostatic potential (MEP) surface calculations showed marked electrostatic contributions to both the Pb?N tetrel bonds and the dimer forming ?+??- stacking interactions. Quantum theory of atoms in molecules (QTAIM) analyses underlined the tetrel bonding character of the Pb?N interactions. The manifold non-covalent interactions found in this supramolecular assembly are the result of the proper combination of the polyfunctional multidentate pyridine-hydrazide ligand and the small nitrito auxiliary ligand.
SUBMITTER: Mahmoudi G
PROVIDER: S-EPMC7571010 | biostudies-literature | 2020 Sep
REPOSITORIES: biostudies-literature
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