A Quantum Chemical Study on the Enormously Large Nonlinear Optical Response of Doped Endohedral Superalkali Na2F and Superhalogens MF4 (M = B,Al) with CNT (C56H16) Cage

In the present communication, the interaction of single-wall carbon nanotubes (SWCNTs) CNT (C56H16) with endohedral doped superhalogens (MF₄:M = B, Al) placed outside of CNT cage and superalkali (Na₂F) placed inside the cage has been studied by using a combination of DFT/B3LYP method and 6–311G(d, p) basis set. The geometry and stability of MF₄@CNT-Li₂F have been studied using optimization parameters, highest occupied molecular orbit (HOMO), lowest unoccupied molecular orbital (LUMO), vibration frequencies, and thermodynamic parameters of absorption reactions. The quantum theory in atoms in molecules (QTAIM) analysis is used to analyze the nature of interactions between MF₄ (M = B, Al) and Na₂F@CNT. Several electronic parameters are computed by using HOMO–LUMO energy. The dipole moment, polarizability, hyperpolarizability, order parameters, anisotropic polarizability, and molar refractivity of MF4@CNT-Li₂F (M = Al, B) are used to calculate the nonlinear optical parameters (MR). The NBO analysis is used to calculate the transfer of charge to stabilized system. The calculated hyperpolarizability of Na₂F@CNT-BF₄/Na₂F@CNT-AlF₄ is nearly 81 times that of reference material urea (40 a.u.). The intramolecular charge transfer (ICT) moment of π electron cloud is responsible for the nonlinear optical behavior of the system.     

Superhalogen and Superacid

A superhalogen F@C₂₀(CN)₂₀ and a corresponding Brønsted superacid were designed and investigated on DFT and DLPNO-CCSD(T) levels of theory. Calculated compounds have outstanding electron affinity and deprotonation energy, respectively. We consider superacid H[F@C₂₀(CN)₂₀] to be able to protonate molecular nitrogen. The stability of these structures is discussed, while some of the previous predictions concerning neutral Brønsted superacids of record strength are doubted. © 2019 Wiley Periodicals, Inc.     

Bottom-up substitution assembly of AuF4−n0,−+nPO3 (n = 1–4): a theoretical study of novel oxyfluoride hyperhalogen molecules and anions AuF4−n(PO3)n0,−

Compounds with high electron affinity, i.e. superhalogens, have continued to attract chemists’ attention, due to their potential importance in fundamental chemistry and materials science. It has now proven very effective to build up novel superhalogens with multi-positively charged centres, which are usually called ‘hyperhalogens’. Herein, using AuF₄^? and PO₃ as the model building blocks, we made the first attempt to design the Au,P-based hyperhalogen anions AuF_4?n(PO₃)_n^? (n = 1–4) at the B3LYP/6-311+G(d)&;SDD and CCSD(T)/6-311+G(d)&;SDD (single-point) levels (6-311+G(d) for O, F, P and SDD for Au). Notably, for all the considered Au,P systems, the ground state bears a dioxo-bonded structure with n ≤ 3, which is significantly more stable than the usually presumed mono-oxo-bonded one. Moreover, the clustering of the –PO₃ moieties becomes energetically favoured for n ≥ 3. The ground states of AuP₄O₁₂^0,? are the first reported cage-like oxide hyperhalogens. Thus, the ?PO₃ moiety cannot be retained during the ‘bottom-up’ assembly. The vertical detachment energy (VDE) value of the most stable AuF_4?n(PO₃)_n^? (n = 1–4) ranges from 7.16 to 8.20 eV, higher than the VDE values of the corresponding building blocks AuF₄^? (7.08 eV) and PO₃^? (4.69 eV). The adiabatic detachment energy values of these four hyperhalogens exceed 6.00 eV. Possible generation routes for AuF_4?n(PO₃)_n^? (n = 1–4) were discussed. The presently designed oxyfluorides not only enriches the family of hyperhalogens, but also demonstrates the great importance of considering the structural transformation during the superhalogen → hyperhalogen design such as for the present Au–P based systems.     

Ab initio investigations on the stabilities of AuOnq− (q = 0 to 3; n = 1 to 4) species: Superhalogen behavior of AuOn (n ≥ 2) and their interactions with an alkali metal

Theoretical density functional calculations are performed on AuO_n^q? species for q = 0–3 and n = 1–4 in various spin states. AuO_n species are found to be relatively more stable in their mono‐anionic forms and behave as superhalogens for n ≥ 2. The maximum oxidation state of Au is found to be +7 in these species, but limited to +5. This fact is explained by considering interactions of AuO_n superhalogens with K atom and which leads to the formation of more stable KAuO_n complex up to n = 3, only. Thus, the present study is expected not only to motivate the synthesis of a new class of salts but also to assign the maximum oxidation state of gold. © 2013 Wiley Periodicals, Inc.