Through explorations of the silicon-tellurium system we identified the extremely air-sensitive, red SiTe≡SiTe that is a silicon-deficient relative of the previously reported SiTe. The crystal structure features hexagonal closest packed layers of tellurium atoms with disordered [Si] dumbbells residing in about 50% of the octahedra of every second layer enclosed by the tellurium atoms. In addition to the determination of the crystal structure for this silicon telluride, we probed the opportunity of the existence of a SiTe adopting the SiTe-structure by means of quantum chemical techniques. The investigations of the electronic structures and a subsequent chemical bonding analysis based on the projected Crystal Orbital Hamilton Population (pCOHP) technique for two "SiTe" models revealed a tendency to align the [Si] dumbbells parallel to the c axis to maximize Si-Te bonding. However, the disorder of the [Si] dumbbells appears to be a consequence of non-equilibrium condensation into the solid state.

Although the electronic structures of several tellurides have been recognized by applying the Zintl-Klemm concept, there are also tellurides whose electronic structures cannot be understood by applications of the aforementioned idea. To probe the appropriateness of the valence-electron transfers as implied by Zintl-Klemm treatments of ALn2Ag3Te5-type tellurides (A = alkaline-metal; Ln = lanthanide), the electronic structure and, furthermore, the bonding situation was prototypically explored for RbPr2Ag3Te5. The crystal structure of that type of telluride is discussed for the examples of RbLn2Ag3Te5 (Ln = Pr, Nd), and it is composed of tunnels which are assembled by the tellurium atoms and enclose the rubidium, lanthanide, and silver atoms, respectively. Even though a Zintl-Klemm treatment of RbPr2Ag3Te5 results in an (electron-precise) valence-electron distribution of (Rb+)(Pr3+)2(Ag+)3(Te2−)5, the bonding analysis based on quantum-chemical means indicates that a full electron transfer as suggested by the Zintl-Klemm approach should be considered with concern.

Differing reports regarding the structural features of the mineral stützite, AgTe (-0.25 ≤ x ≤ 1.44), and the quest for tellurides with low-dimensional fragments stimulated our impetus to review this system by employing experimental as well as quantum-chemical methods. Determination of the crystal structures for three samples with compositions AgTe (I), AgTe (II), and AgTe (III) revealed considerable positional disorders for the Ag and Te sites and previously unknown structure models for I and II, which differ from that of III through the stacking sequences of honeycomb-fashioned Te layers. The crystal structures comprise [Te@Ag]@Te units in the forms of bicapped hexagonal Te antiprisms that enclose Te-centered tricapped trigonal Ag prisms, while each Te atom is encapsulated by Ag atoms assembling diverse types of coordination polyhedra. The vibrational and electronic properties were determined for three models approximating the actual crystal structure of stützite by means of techniques based on first principles. From analyses of the electronic structures and projected crystal orbital Hamilton populations (pCOHP), it is clear that the amounts and distributions of the Ag atoms within the Te network should be influenced by the subtle interplay between the attempts to achieve an electronically favorable situation with a gap at E and minimize the occupations of antibonding states.

Copper nitrene complexes are highly reactive species and are known as intermediates in the copper catalyzed C-H amination. In this study, three novel copper tosyl nitrene complexes were synthesized at...