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Abstract
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Treatment of lead(II) acetate, Pb(CH3COO)2·3H2O, with an isonicotinoylhydrazone building block (HL) and in the presence of two different salts (NaN3 or NaClO4) as a source of auxiliary ligand, resulted in two novel coordination compounds, namely a discrete 0D complex [Pb4(μ3-L)(L)(μ-N3)(N3)][Pb(L)(N3)(MeOH)]·0.75MeOH (1) and a 2D coordination polymer [Pb(μ-L)(μ-CH3COO)Na(μ-ClO4)(MeOH)]n (2), respectively. A related reaction of Pb(NO3)2 with HL afforded a different product [Pb(μ-L)(NO3]n (3), which is a 1D coordination polymer. All compounds were isolated in good yields as air-stable solids and were fully characterized by elemental analysis, FTIR spectroscopy, single crystal X-ray diffraction, topological analysis, and theoretical calculations. An interesting feature of all structures 1–3 concerns the hemi-directional coordination of Pb(II) atoms and the observation of tetrel bonds [noncovalent Pb⋯N/O interactions], which were analyzed in detail by DFT calculations and Hirshfeld surface analysis. In fact, tetrel bonding interactions are responsible for the extension [0D → 2D (in 1) or 1D → 2D (in 3)] or reinforcement [(2D → 2D (in 2)] of the crystal structures, thus giving rise to intricate 2D supramolecular layers. After simplification, these layers were analyzed and classified from the topological perspective, disclosing binodal 3,5-connected underlying nets with the same 3,5L24 topology in 1 and 2 but being constructed from structurally distinct components, and a binodal 3,6-connected net with the 3,5L60 topology in 3.
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