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[en] We investigate the chemical functionalization effect on the structural and electronic properties of SnC monolayer using first-principles calculations. Specifically, the chlorinated-, fluorinated- and Janus-functionalized monolayers are considered. Based on our calculations, the pristine SnC monolayer is dynamically stable with a planar structure. Its electronic band gap calculated with the HSE06 hybrid functional is 2.371 eV. The inclusion of halogen atoms (F and Cl) destroys the planarity and transforms the hybridization from sp 2 to sp 3. The half-halogenation induces the metallization of the SnC monolayer, while the indirect-to-direct band gap transition can be reached by means of the full-halogenation and Janus-functionalization. Results show that the pristine SnC monolayer electronic structure can be effectively modulated by the chemical functionalization. Therefore, we hope that results presented herein can be of good reference for the SnC monolayer practical applications as well as other 2D materials. (paper)
[en] We have introduced a new, effective and direct multihalogenations of 2,2',5',2"-terthiophene under mild and ambient conditions using 2-halo-4,5-dichloropyridazin-3(2H)-ones. The present system is a rapid and facile methods. 2-Halopyridazin-3(2H)-ones are easily prepared from 4,5-dichloropyridazin-3(2H)-one, which is commercially available, stable, and reusable. We envision more useful cascade multihalogenation of oligothiophenes or compounds involving terthiophene moiety, and efforts in this direction are under way. Recently, we demonstrated utility as synthetic auxiliaries of 2-substituted-pyridazin-3(2H)-ones due to pyridazin-3(2H)-ones are inexpensive, stable and easily prepared heterocycles. 2-Halopyridazin-3(2H)-ones were also developed as useful and eco-friendly electrophilic halogenating agents. Since pyridazin-3(2H)-ones have some advantages involving the formation of stable anions and the electron acceptable moiety, we explored the application of 2-halopyridazin-3(2H)-ones for the halogenation of electron rich compounds as electrophilic halogen sources
[en] Graphical abstract: The presence of one halogen opposite the N results in strong attraction between P and N. This force is little affected by identity of Y atoms, whether H or halogen. Highlights: → Strong attractive force directly between trivalent P and N atoms. → P...N force is unlike H-bonds or halogen bonds, but stronger than both. → Multiple halogenation beyond a single atom on P slightly weakens the interaction. - Abstract: The attractive noncovalent interaction of a P atom with N is derived primarily from two sources. Charge transfer from the N lone pair into the σ* antibonding orbital of a P-X bond that is turned away from the N atom combines with attractive Coulombic forces. As in the case of H-bonding, which is parallel in some ways to P...N attraction, placement of an electron-withdrawing substituent on the P atom enhances both of these components, and strengthens the overall interaction. However, in stark contrast with H-bonding, halogenation beyond monosubstitution does not lead to any further strengthening of the P...N noncovalent bond. Indeed, di and tri-substitution lead to small reductions in the interaction energy. In all cases, the geometry which contains a P...N bond is more stable than other candidate structures, some of which contain hydrogen or halogen bonds.
[en] Because of a moderate reaction rate, it is possible to determine the course of the sequential electrophilic halogenation of 1-SB9H9. The directive effect of the sulfur heteroatom does not correlate with the ground-state charge distribution of 1-SB9H9. It appears that initial attack is at the 6 position instead of the anticipated 10 position. In the care of monobromination and monoiodination there is a significant degree of rearrangement to also give the thermodynamically more stable 10 isomer in the reaction mixture (ΔH/sub isomerization/ = 6.8 kcal/mol). Only the 6 isomer results from monochlorination. Rearrangement is also a significant factor as halogenation becomes more extensive. The initial halogenation of SB11H11 is analogous to that of 1-SB9H9. The site of initial deuteration was not established clearly, but under forceful conditions deuteration was not complete and 6,7,8,9,10-D5-1-SB9H4 and 7,8,9,10,11,12-D6-1-SB11H5 were obtained
[en] This paper reports that conventional halogenation reactions involving f elements typically employ high-temperature conditions. Recent synthetic techniques use halogenation agents that are either inherently reactive or have been activated by physical methods such as photolysis. These techniques allow lower temperature syntheses. Consequently, they have significant advantages with respect to safety, material compatibility, and accountability, as well as providing routes to thermally unstable materials