Supramolecular aggregation of lead(II) perchlorate and a thiosemicarbazide derivative linked by a myriad of non-covalent interactions

Abstract

In this work, we report on a new lead(II) coordination complex [Pb2L2(CH3CN)(ClO4)2]·2H2O (1·2H2O), which was readily synthesized from a mixture of Pb(ClO4)2·3H2O and 1-(pyridine-2-yl)benzylidene-4-phenylthiosemicarbazide (HL). The crystal structure analysis of 1·2H2O evidenced that the lead(II) cation is N,N',S-chelated by the tridentate pincer type L with formation of a [PbL]+ coordination species, which dimerizes through a couple of reciprocal bridging Pb–S bonds, yielding the [Pb2L2]2+ complex cation. The metal centers within this cation are linked by two Pb∙∙∙N tetrel bonds through the bridging acetonitrile molecule with the formation of a [Pb2L2(CH3CN)]2+ building unit. These units are glued by reciprocal Pb∙∙∙S tetrel bonds, yielding a 1D supramolecular polymeric chain. The lead(II) cations interact also with disordered oxygen atoms of both the minor and major occupancies of the perchlorate anions either through covalent Pb–O bonds or Pb∙∙∙O tetrel bonds, respectively. 1D polymeric chains resemble an expanded hexagonal projection and span along the a axis, yielding a grid-like crystal packing, where the cavities are filled by lattice water molecules. The interactions have been studied using DFT calculations and characterized by using the quantum theory of atoms-in-molecules (QTAIM) and the non-covalent interaction plot (NCIplot) computational tools.