Metal–organic and supramolecular lead(ii) networks assembled from isomeric nicotinoylhydrazone blocks: the effects of ligand geometry and counter-ion on topology and supramolecular assembly

Abstract

A new series of six structurally diverse leadIJII) coordination compounds was assembled from two isomeric nicotinoylhydrazones as neutral ligands and three PbIJII) salts with different monoanions (chloride, nitrate and thiocyanate) as starting materials. The products were isolated in good yields and were fully characterized, including by single-crystal X-ray diffraction and theoretical methods. Within the six compounds, three feature 2D metal-organic networks, two are 1D coordination polymers, and another one comprises discrete 0D dimeric units. The structures of the latter low dimensional compounds are extendable into 2D supramolecular networks. The topology of the coordination or supramolecular networks is primarily dictated by the geometry of the nicotinoylhydrazone used as a main building block. In contrast, supramolecular interactions are greatly influenced by the choice of the anion in the starting leadIJII) salt, which is demonstrated by Hirshfeld surface analysis. In fact, the topological analysis and classification of metal-organic or supramolecular underlying networks in the obtained compounds was performed, disclosed the hcb, 2C1, gek1, SP 1-periodic net (4,4)(0,2) and 3,4L83 topological types; the latter topology was documented for three compounds, including both coordination and supramolecular networks. In the two compounds containing thiocyanate moieties, there are supramolecular contacts between the thiocyanate anions and lead centres. These were shown by DFT calculations to be strong tetrel bonds (−15.3 and −16.7 kcal mol −1 ) between the σ-hole of the lead atom and the π-system of the thiocyanate S-C bond.CrystEngComm, 2016, 18, 5375-5385 | 5375This journal is

Syntheses, Characterization, and Fluorescence Properties of Four Divalent Lead Coordination Polymers based on Zwitterionic Ligands

“…The Pb 2+ ion exhibits six‐coordinate configuration defined by two μ 2 ‐Cl – ions and four carboxylic oxygen atoms that come from one chelating acetic acid and one ligand L 2 . The bond lengths of Pb‐Cl are 2.7708(15) Å and 3.121(3) Å, and the bond lengths of Pb–O are changing from 2.379(5) to 2.736(5) Å, which are comparable to those of the reported Pb‐based coordination polymers . Six‐connected Pb 2+ and its symmetry generated counterparts are linked together by μ 2 ‐Cl – and μ 2 ‐CH 3 COO – from ligand L 2 to generate an infinite “PbCl(CH 3 COO)” chain extending along [0 1 0] direction.…”

Hexacoordinated Tetrel‐Bonded Complexes between TF4 (T=Si, Ge, Sn, Pb) and NCH: Competition between σ‐ and π‐Holes

“…[25,26,38,98,99] Previous studies have confirmed the trend that the tetrel bond grows stronger as T becomes larger, [30,32,33,47,100] but that the effect levels off between Sn and Pb. However, there are a few works dealing with tetravalent Sn and Pb, and the noncovalent bonds they form with various bases.…”

“…However, there are a few works dealing with tetravalent Sn and Pb, and the noncovalent bonds they form with various bases. [25,26,38,98,99] Previous studies have confirmed the trend that the tetrel bond grows stronger as T becomes larger, [30,32,33,47,100] but that the effect levels off between Sn and Pb. [45,101] An earlier work [45,102] supports the result noted here that the deformation energy induced within the Lewis acid molecule by formation of a tetrel bonded complex drops as the central tetrel atom grows in size.…”

Ability of IR and NMR Spectral Data to Distinguish between a Tetrel Bond and a Hydrogen Bond

“…The term "tetrel bond" was first coined in 2013 17 where it was related to atoms below C in this family of the periodic table. And indeed it is to these heavier atoms that most previous work has been devoted [18][19][20][21][22][23][24][25][26] . In the case of the C atom, its ability to engage in a TB has typically been amplified by adding a number of electron-withdrawing substituents like F [27][28][29] rather than considering a CH3 group itself.…”