Extended lead(II) architectures engineered via tetrel bonding interactions

The evaluation of N'-pyridin-2-ylmethylene) nicotinohydrazide (HLI) and N, N'"-bis(1-(pyridin-2-yl)-thylidene)carbazide (H2LII) as linker precursors in the synthesis of novel PbII extended structures is described. An equimolar one-pot reaction of PbX2 (X = NO3-, H3COO-) salts with HLI and H2LII in MeOH at 60 degrees C in a branched tube apparatus leads to heteroleptic complexes [Pb(HLI)(NO3)(2)](n) (1), [Pb(L-I)(CH3O)](n) (2), [Pb-2(H2LII)(NO3)(4)] (3) and [Pb-2(HLII)(CH3COO)(3)](n) (4), respectively. The nature of the anion in the parent PbII salt also influences the final structure. In all complexes, the PbII center exhibits a hemidirected coordination geometry with all the covalent bonds being concentrated on one hemisphere of the coordination sphere. The sterically available PbII ion participates in Pb center dot center dot center dot O/N tetrel bonding or Pb center dot center dot center dot Cg interaction as evidenced from the detailed structural and topological analysis of the described complexes. As a result of these interactions, the structures of all four compounds can be extended to a higher dimensional framework, which is further stabilized by hydrogen N-H center dot center dot center dot O/C-H center dot center dot center dot O and dihydrogen C-H center dot center dot center dot H-C bonds and/or pi center dot center dot center dot pi stacking interactions. The complementary Hirshfeld surface analysis of the discrete complex 3, considering covalent bonds, showed that the structure is highly dominated by H center dot center dot center dot X (X = O, H and C) and O center dot center dot center dot Y (Y = O, Pb, C and N) contacts, of which the O center dot center dot center dot Pb/H/N/C contacts are highly favoured. DFT based charge and energy decomposition (ETS-NOCV) calculations are performed in order to shed light on the nature of the non-covalent interactions that determine the stability of the obtained structures.