The synthesis and characterization of substituted benzimidazolin-2-selones (4c–4d) and -tellone (4i) are reported. Upon reaction with halogens (I2, Br2, and Cl2), these selones and tellone yield dihaloselones/tellone (5c–5i). The reaction of dihaloselones with elemental tellurium/tin/bismuth leads to the formation of selone-coordinated monomeric tellurium tetrahalides, tellurium dibromide (8), tin tetrahalides, and bismuth triiodide adducts (7a–7g), respectively. The structures of the tellurium tetrahalide (7a, 7d, and 7g), tellurium dibromide (8), tin tetrahalide, and bismuth triiodide adducts have been established by single-crystal X-ray analysis. The bismuth triiodide adduct is the first neutral tetrameric structure with selones. The bismuth adduct has been used as a single-source precursor for the synthesis of bismuth selenide (Bi2Se3) nanoparticles, which were characterized by powder XRD patterns. The TEM images show the hexagonal shape of the nanoparticles.