A Theoretical Study on the Influence of Five- and Six-Membered N-Heterocyclic Ring Side Chains of the N-Donor Extractants on Am(III)/Eu(III) Extraction and Separation.

According to the green development requirements of carbon neutrality and carbon peaking, the effective separation of lanthanides and actinides is one of the key factors for nuclear energy to become a sustainable energy source. In recent years, o-phenanthroline-based ligands have been proven to be effective in the separation of lanthanides and actinides. In this work, based on 5,9b-dihydro-4aH-cyclopenta[1,2-b:5,4-b']dipyridines, we designed six N-heterocyclic ring ligands and theoretically studied their extraction capacity and separation selectivity for the Am(III) and Eu(III) ions.

Theoretical investigations into the bonding and separation properties of non-rigid, partially rigid, and rigid ligands derived from Et-Tol-PTA with trivalent lanthanides and actinides.

The separation of trivalent actinide elements from lanthanide elements represents one of the most formidable challenges within the context of nuclear waste partitioning and transmutation (P&T) processes. Consequently, we embarked on a systematic investigation aimed at elucidating the bonding properties and thermodynamic behavior of a -ethyl--tolyl-2-amide-1,10-phenanthroline (Et-Tol-PTA) ligand in conjunction with trivalent actinide and lanthanide elements. This investigation involved the utilization of various density functional theory (DFT) methods and a comparative analysis between small-core pseudopotential basis sets and all-electron basis sets.

Theoretical investigation on the ligands constructed from phenanthroline and five-membered N-heterocyclic rings for bonding and separation properties of Am(III) and Eu(III).

The ligands, derived from the combination of phenanthroline and various five-membered N-heterocyclic rings, were subject to a comprehensive investigation for their potential in the extraction and separation of actinides and lanthanides. This study employed DFT methods to thoroughly explore the properties of both phenanthroline (Ph) and the diverse five-membered N-heterocyclic rings (R1-R8). Additionally, tridentate ligands RPh ( = 1-8) and tetradentate ligands RPhR (, = 1-8) were analyzed in detail, encompassing their electrostatic potential (ESP), protonation energy, coordination bonding with the metals Am(III) and Eu(III), and the thermodynamics of extraction separation for Am(III) and Eu(III).

Theoretical Study on the Coordination and Separation Capacity of Macrocyclic N-Donor Extractants for Am(III)/Eu(III).

Designing ligands that can effectively separate actinide An(III)/lanthanide Ln(III) in the solvent extraction process remains one of the key issues in the treatment of accumulated spent nuclear fuel. Nitrogen donor ligands are considered as promising extractants for the separation of An(III) and Ln(III) due to their environmental friendliness. Four new macrocyclic N-donor hexadentate extractants were designed and their coordination with Am(III) and Eu(III), as well as their extraction selectivity and separation performance for Am(III) and Eu(III), were investigated by scalar relativistic density functional theory.

Long-bonding and bonding nature in noble gas insertion compounds MNgBY of transition metal-boron bond.

The nature of inert gas bonding has always been an important topic. The bonds of noble gases cover the entire range of chemical bonds, from the weakest van der Waals forces, to non-covalent interactions, and to covalent bonds. Two types of methods were used to investigate the properties of chemical bonds in the inert gas inserted compound MNgBY with the transition metal M = Cu/Ag/Au and substituents Y = O/S/NH, one based on orbital analysis and the other based on electron density analysis.

OBCN isomerization and noble gas insertion compounds of identical valence electron number species: stability and bonding.

A series of new noble gas (Ng) insertion compounds of the general type XNgX, XNgY and XNgY+ has been theoretically studied using ab initio and DFT methods herein. We first studied the isomerization process of the OBCN compound, and then investigated the bonding properties and stability of the compounds formed by inserting Ng into the single bond of the three low energy isomers by high-level ab initio calculations. The OBNgCN compounds are thermochemically stable with respect to all dissociation channels except for the processes of releasing OBCN/OBNC and free Ng.

RgBeB: theoretical investigation of BeB and its rare gas capability.

A series of BeB and its rare gas (Rg) containing complexes RgBeB (Rg = He-Rn, n = 1-6) have been predicted theoretically using the B3LYP, MP2, and CCSD(T) methods to explore structures, stability, charge distributions, and nature of bonding. Both BeB and RgBeB are the global minima on the potential energy surfaces. In the RgBeB complexes, the dissociation energy drops with the increase in number of Rg.

Noble gas inserted compounds of borazine and its derivative BNR: structures and bonding.

Quantum chemistry computations were performed at the MP2 and B3LYP levels of theory using the basis sets aug-cc-pVDZ and def2-TZVPPD to study the noble gas (Ng) compounds formed by insertion of a Ng atom (Kr, Xe, Rn) into the B-H/F and N-H/F bonds of inorganic benzene BNH and its fluorine derivative BNF. The geometrical structures were optimized and vibrational analysis was carried out to demonstrate these structures being local minima on the potential energy surface. The thermodynamic properties of the formation process of Ng compounds were calculated.

Compounds with Rare Gas-Selenium/Tellurium Bonds: A Theoretical Investigation on FRgLF and FRgLF (Rg = Kr-Rn, L = Se and Te, n = 1, 3, and 5).

A new type of interesting insertion compounds FRgLF (Rg = Kr-Rn, L = Se and Te, n = 1, 3 and 5) and ionic FRgLF obtained through the insertion of a rare gas atom into the selenium fluorides and tellurium fluorides have been explored theoretically using MP2, CCSD(T), and PBE0 calculations. These predicted species were examined to present the optimized geometries, vibrational modes, molecular properties, thermodynamic and kinetic stabilities and bond nature. The optimized structures are without imaginary frequencies and metastable.

Hydrogen bond strengthening between o-nitroaniline and formaldehyde in electronic excited states: A theoretical study.

To study the hydrogen bonds upon photoexcited, the time dependent density function method (TD DFT) was performed to investigate the excited state hydrogen bond properties of between o-nitroaniline (ONA) and formaldehyde (CHO). The optimized structures of the complex and the monomers both in the ground state and the electronically excited states are calculated using DFT and TD DFT method respectively. Quantum chemical calculations of the electronic and vibrational absorption spectra are also carried out by TD DFT method at the different level.

Noble gas supported boron-pentagonal clusters BNg: exploring the structures and bonding.

A novel type of trivalent BNg five-membered cational species BNg(Ng = He~Rn, n = 1~5) has been found and investigated theoretically using the B3LYP and MP2 methods with the def2-QZVPPD and def2-TZVPPD basis sets. The geometry, harmonic vibrational frequencies, bond energies, charge distribution, bond nature, aromaticity, and energy decomposition analysis of these structures were reported. The calculated B-Ng bond energy is quite large (the averaged bond energy is in the range of 209.

Monocyclic aromatic compounds BRg of boron and rare gases.

The monocyclic compounds (BRg)(D), (BRg)(D), (BRg)(D) and (BRg)(D) formed between boron and rare gases Rg (He-Rn) are theoretically predicted to be stable structures and have π-aromaticity with a delocalized nc-2e π-system. For heavier rare gases Ar-Rn, the B-Rg bond energy is quite high and ranges from 15 to 96 kcal mol, increasing with the ring size and the atomic number of rare gases; the B-Rg bond length is close to the sum of covalent radii of B and Rg atoms; NBO and AIM analyses show that the B-Rg bonds for Ar-Rn have a typical covalent character. The B-Rg bond is stabilized mainly by σ-donation from the valence p orbital of Rg to the vacant valence orbital of the boron ring.

Substituent effects on the properties of the hemi-bonded complexes (XH2P···NH2Y)(+) (X, Y=H, F, Cl, Br, NH2, CH3, OH).

Ab initio calculations have been performed to study the structures, binding energies, and bonding properties of the hemi-bonded binary complexes (XH2P···NH2Y)(+) with the substituents X and Y being H, F, Cl, Br, NH2, CH3, and OH. The P···N interactions in these open-shelled systems have typical pnicogen bond characteristics but much stronger than the usual pnicogen bonds in closed-shell systems. This P···N bond can be strengthened by an electron-withdrawing substituent X or an electron-donating substituent Y, the bonding energy varies from 17 kcal mol(-1) of (CH3H2P···NH2F)(+) to 54 kcal mol(-1) of (FH2P···NH2CH3)(+).

Theoretical Predictions of C3v Symmetric Three-H-Bridged Noble Gas Compounds NgBeH3BeR, NgBeH3BR(+), and NgBH3BR(2).

A new series of stable noble gas-Lewis acid compounds NgBeH3BeR, NgBeH3BR(+), and NgBH3BR(2+) (R = F, H, CH3, Ng = He-Rn) with three 3c-2e H-bridged bonds have been predicted by use of the PBE0 and MP2 methods. The Ng-Be/B bonds are strong and have large binding energies 35-130, 9-38, and 4-13 kcal/mol for the doubly charged cations, singly charged cations, and neutral molecules, respectively. The binding energy and strength of the Ng-Be/B bonds increase largely from He to Rn but are insensitive to electronegativity of the substituent R.

A comparative study of the chalcogen bond, halogen bond and hydrogen bond S⋯O/Cl/H formed between SHX and HOCl.

Ab initio quantum chemistry methods were used to analyze the noncovalent interactions between HOCl and SHX (X = F, CN, NC, Cl, Br, NO2, CCH, CH3, H). Three energetic minimal configurations were characterized for each case, where the S center acts as a Lewis acid interacting with O to form a chalcogen bond, as well as a Lewis base interacting with Cl or H of HOCl to form halogen bond and hydrogen bond, respectively. An electronegative substituent such as F, CN, NC and NO2 tends to form a stronger chalcogen bond, while an electropositive substituent such as CCH, CH3 and H is inclined to form a more stable H-bonded complex.

Theoretical study on effects of hydrogen bonding on the ring stretching modes of pyridine.

Pyridine generally acts as the proton acceptors in the hydrogen bonding interaction by using its lone pair n(N) or pi-electrons. Some previous research indicated that for the N-type H-bond, the ring breathing mode v(1), the N-para-C stretching mode v(6a) and the meta-CC stretching mode v(8a) of pyridine showed a frequency blueshift but the triangle mode v(12) had no change in frequency. Both electrostatic interaction and charge transfer caused by intermolecular hyperconjugation n(N)-->sigma( *)(HX) have contributions to the frequency blue shifts, while charge transfer is predominant at equilibrium intermolecular distance.

Electronic properties of multifurcated bent hydrogen bonds CH3...Y and CH2...Y.

H-bonding angle angleYHX has an important effect on the electronic properties of the H-bond Y...

Chemical origin of blue- and redshifted hydrogen bonds: intramolecular hyperconjugation and its coupling with intermolecular hyperconjugation.

Upon formation of a H bond Y...

Theoretical investigation of hydrogen bonds between CO and HNF2, H2NF, and HNO.

Ab initio quantum mechanics methods were applied to investigate the hydrogen bonds between CO and HNF2, H2NF, and HNO. We use the Hartree-Fock, MP2, and MP4(SDQ) theories with three basis sets 6-311++G(d,p), 6-311++G(2df,2p), and AUG-cc-pVDZ, and both the standard gradient and counterpoise-corrected gradient techniques to optimize the geometries in order to explore the effects of the theories, basis sets, and different optimization methods on this type of H bond. Eight complexes are obtained, including the two types of C.