Density functional theory (DFT) calculations were carried out to investigate the hydridic character of several main group hydrides. A P-hydrido-1,3,2-diazaphospholene 1f with two π-electron donor amino groups on the heterocyclic skeleton framework performs as a strong hydride donor owing to the significant n(N)–σ*(P–H) hyperconjugation. The natural bond orbital analysis reveals that high π-electron delocalization exists in both 1f and the corresponding stable phosphenium Ef+.
As one of the most important chemical reactions, SN2 reactions play a central role in both synthetic chemistry and the development of mechanistic paradigms. Most of the previous attention has centered on substitution at carbon, whereas displacement at nitrogen is clearly less studied and less understood. The SN2@N reactions have enormous synthetic potential, especially in heterocyclic chemistry, which is a cornerstone of medicinal chemistry, and has been receiving increasing attention, both experimentally and computationally.
The first ruthenabenzothiophenes have been achieved via the C–H activation of thiophene. These species feature high thermal stability and resistance of a moderate oxidant, which constitute valuable addition to the rare metallaaromatic containing second-row transition metals.
Two newly discovered linear compounds tetraboronate and boroxine stabilized by digermylene are reported, which feature a B4O5 chain and a B3O3 ring, respectively. DFT calculations reveal that not only can digermylene stabilize the electron-deficient boron centers, but also increase the energies of the LUMOs of the boron moiety. Our results provide a hint for the development of boronate covalent organic frameworks.
Aromaticity, one of the most important concepts in organic chemistry, has attracted considerable interest from both experimentalists and theoreticians. It remains unclear which NICS index is best to evaluate the triplet-state aromaticity. Here, we carry out thorough density functional theory (DFT) calculations to examine this issue. Our results indicate that among the various computationally available NICS indices, NICS(1)zz is the best for the triplet state.
Aromaticity, an old but still fantastic topic, has long attracted considerable interest of chemists. Generally, π aromaticity is described by π-electron delocalization in closed circuits of unsaturated compounds whereas σ-electron delocalization in saturated rings leads to σ aromaticity. Interestingly, our recent study shows that σ aromaticity can be dominating in an unsaturated three-membered ring (3MR) of cyclopropaosmapentalene. An interesting question is raised: Can the σ aromaticity, which is dominant in the unsaturated 3MR, be extended to other cyclopropametallapentalenes?