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The nature of π-hole spodium bonds in the HgLCl2⋯ZH3/CH2Y complexes (L = pyrrole 1, pyrazole 2, imidazole 3, pyridine 4, pyridazine 5, and pyrimidine 6; Z = N, P, As, and Sb; Y = O, S, Se, and Te) has been studied using theoretical calculations. The electrophilicity of the π-hole in the tri-coordinated HgII complexes varies with the type of N-heterocyclic ligand. The strength and nature of the π-hole spodium bond is closely related to the properties of the Lewis bases. In the case of HgLCl2⋯ZH3, the strength of the π-hole spodium bond weakens as the nucleophilicity of the base decreases, following the sequence HgLCl2⋯NH3 > HgLCl2⋯PH3 > HgLCl2⋯AsH3 > HgLCl2⋯SbH3. The Hg⋯Z spodium bonds change from a partially covalent interaction to a close-shelled noncovalent interaction. The nucleophilic ability of CH2Y decreases in the order CH2O > CH2S > CH2Se > CH2Te, while the strength of the π-hole spodium bond follows the order HgLCl2⋯OCH2 < HgLCl2⋯SCH2 < HgLCl2⋯SeCH2 < HgLCl2⋯TeCH2. The Hg⋯Y spodium bond undergoes a transition from a close-shelled noncovalent to a partially covalent interaction, resulting in an incremental increase in the degree of covalence. The Hg⋯Te spodium bond exhibits certain characteristics resembling those of a coordinate covalent bond. The inter-orbital interactions observed in the formation of the HgLCl2⋯YCH2 complexes appear to be significantly stronger compared to those observed in the HgLCl2⋯ZH3 complexation. [ABSTRACT FROM AUTHOR]

Environment-benign one-pot three-component cycloadditions of diazo compounds, nitrosoarenes and vinyl pyrimidines, or vinyl purines, or vinyl imidazoles, or vinyl triazoles or vinyl indole have been developed. This catalyst- and additive-free strategy could efficiently introduce the isoxazolidine skeleton into nucleoside analogues, oxazole molecules and indole derivatives to provide diverse classes of isoxazolidinyl pyrimidine nucleoside analogues, isoxazolidinyl purine nucleoside analogues, isoxazolidinyl imidazoles, isoxazolidinyl triazoles and isoxazolidinyl indole with moderate to good yields for most substrates. [ABSTRACT FROM AUTHOR]