Chemists look at reagents containing the less researched (compared to sulfur)
chalcogen elements selenium and tellurium.
Due to their 2D hexagonal arrangement, some TMDs such as Mo[S.sub.2] have a transition metal atom sandwiched between two
chalcogen atoms forming a S--Mo--S layer [1].
In comparison with halogen or
chalcogen, it is important to bear in mind the tiny ability of the carbon for donating electrons, even though the existence of [C.sup....]H was verified and valued by theoretical calculations and experimental analyses [176].
Manikanda, "Sizecontrolled synthesis of
chalcogen and chalcogenide nanoparticles using protic ionic liquids with imidazolium cation," Korean Journal of Chemical Engineering, vol.
Benchouck, "Optical properties of CuAl[X.sub.2] (X=Se, Te) thin films obtained by annealing of copper, aluminum and
chalcogen layers sequentially deposited," Thin Solid Films, vol.
TMDs are compounds composed of a transition metal such as molybdenum or tungsten and a
chalcogen (typically sulfur, selenium or tellurium, although oxygen is also a
chalcogen).
Interest in softer
chalcogen (S and Se) containing complexes is rapidly increasing because of their potential application in bioinorganic and coordination chemistry [14].
Jantan et al., "Bifunctional
chalcogen linkers for the stepwise generation of multimetallic assemblies and functionalized nanoparticles," Inorganic Chemistry, vol.
Vargas-Baca's own interest was with other heavy elements, specifically those in Group 16 of the periodic table known as the
chalcogens. His work revealed examples of cyclic molecules that formed automatically when single tellurium-oxygen
chalcogen bonds took the place of hydrogen bonds, a process unlike anything seen in halogen bonding.
For example, in the A-B intraverbal, the antecedent stimuli were, "Name the boron [-group] element" and the correct response was "indium"; in the B-C intraverbal, the antecedent stimuli were "Name the atomic number of the indium" and the correct response was "49." The other two A-B and B-C intraverbals were analogous, referred to the
chalcogen group, polonium, and the atomic number 84.