Exploring the role of strong intramolecular coordination of the 2-(2'-pyridyl)phenyl group in heavy main group halides: insights from synthesis, structural, and bonding analyses

By the transmetallation of ppyHgCl [ppy = 2-(2'-pyridyl)phenyl] (1) with SnCl4 and SbCl3, the synthesis of the monoorgano main group halides, [ppySnCl(3)(H2O)]center dot 2(0.5diox) (diox = 1,4-dioxane) [2(H2O)]center dot 2(0.5diox) and [ppySbCl(2)] (3) was achieved. The reaction of 1 with BiCl3 does not give the analogous monoorganobismuth dichloride. Instead, it results in the formation of [(ppy)(2)Bi](+)center dot[ppyBiCl(3)](-) (4). Reactions of (ppy)(2)Te and (ppyTe)(2) with SO2Cl2 and Br-2 result in the formation of ppyTeCl (5) and ppyTeBr (6) respectively. All the synthesized compounds were characterized by multi-nuclear NMR spectroscopy (H-1, C-13, Sn-119, and Te-125), FT-IR spectroscopy, ESI-MS, CHN analysis, and single-crystal X-ray diffraction studies. The molecular structures of 2-6 reveal strong intramolecular coordination of the N-atoms of the pendant arms with the main group element centers. DFT calculations; including Natural Bond Order (NBO), Electron Localization Function (ELF), Electrostatic Surface Potential (ESP) and Atoms in Molecules (AIM) infer that the stability of 2-6 relies on the sigma-hole participation of the element center with the N-lone pair of the pyridyl arm