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This work explores the synthesis and DFT study of five tetranuclear Pb(II) complexes and the role of tetrel bonding in their crystal engineering. Three synthesised Pb(II) complexes and two theoretical tetrameric Pb(II) complexes with halogenated thiophene carboxylate and 1,10-phenanthroline ligands are reported here. Their structural configurations, which feature chair-like repeating units connected via oxygen bridges, without Pb–Pb bonds, show two types of packing arrangements. Each Pb atoms form hemidirectional coordination creating space for the formation of tetrel bonds. The close packed arrangements are stabilised and guided by tetrel bonds. The Pb⋯Br tetrel bonds were found to contribute −4.38 kcal mol−1 and Pb⋯Cl −3.37 kcal mol−1 for the stability of the complexes. These tetrel bonds direct the packing arrangements within the crystal lattice. Additionally, open packed arrangements are stabilised by hydrogen bonds. These findings offer new insights into the design of lead-based metal organic frameworks and highlights the critical role of tetrel bonds in the crystal architecture. [ABSTRACT FROM AUTHOR]

The possibility of simultaneous addition of η2-H2 to both the metals (Ni and Fe) in the active site of the as isolated state of the enzyme (Ni-SI) is examined here by an atom-by-atom electronic energy partitioning based on the QTAIM method. Results show that the 4LS state prefers H2 removal than addition. Destabilization of the atomic basins of the thiolate bridges and decrease of the electrophilicity of the Fe and Ni, resulting in poor back donation to the CO ligand, are the bottlenecks that hamper dihydrogen activation simultaneously. The study helps to understand why such states are seldom accessed in the activation of dihydrogen. Moreover, Ni has been found to be the natural choice for the dihydrogen binding. [ABSTRACT FROM AUTHOR]