Dinuclear superhalogen anions containing two different central atoms

Electron Propagator Theory of Vertical Electron Detachment Energies of Anions: Benchmarks and Applications to Nucleotides

A new generation of ab initio electron-propagator self-energy approximations that are free of adjustable parameters is tested on a benchmark set of 55 vertical electron detachment energies of closed-shell anions. Comparisons with older self-energy approximations indicate that several new methods that make the diagonal self-energy approximation in the canonical Hartree-Fock orbital basis provide superior accuracy and computational efficiency. These methods and their acronyms, mean absolute errors (in eV), and arithmetic bottlenecks expressed in terms of occupied (O) and virtual (V) orbitals are the opposite-spin, non-Dyson, diagonal second-order method (os-nD-D2, 0.2, OV²), the approximately renormalized quasiparticle third-order method (Q3+, 0.15, O²V³) and the approximately renormalized, non-Dyson, linear, third-order method (nD-L3+, 0.1, OV⁴). The Brueckner doubles with triple field operators (BD-T1) nondiagonal electron-propagator method provides such close agreement with coupled-cluster single, double, and perturbative triple replacement total energy differences that it may be used as an alternative means of obtaining standard data. The new methods with diagonal self-energy matrices are the foundation of a composite procedure for estimating basis-set effects. This model produces accurate predictions and clear interpretations based on Dyson orbitals for the photoelectron spectra of the nucleotides found in DNA.

Design of a Novel Series of Hetero-Binuclear Superhalogen Anions MM′X4− (M = Li, Na; M′ = Be, Mg, Ca; X = Cl, Br)

A series of hetero-binuclear superatom motifs involving chloride/bromide ligands, that is, MM′X₄⁻ (M = Li, Na; M′ = Be, Mg, Ca; X = Cl, Br) anions, have been characterized by using many-body perturbation theory calculations. Large vertical electron detachment energies (VDEs, 5.470–6.799 eV) confirm the superhalogen identity of these anions. A larger VDE value can be obtained by introducing small M or large M′ central atoms and small halogen ligand atoms. Thus, one isomer of LiCaCl₄⁻ possesses the largest VDE value. Besides, when the extra electron is shared by all ligand atoms or three bridging ligand atoms, the isomers have relatively larger VDE values.

Tripodal Podand Ligand with a Superhalogen Nature as an Effective Molecular Trap

Tris(2-methoxyethyl) fluoroborate anion (TMEFA), anovel tripodal ligand based on the BF4− superhalogen anion, is proposed and was investigated theoretically using ab initio MP2 (second-order Møller-Plesset perturbational method) and OVGF (outer valence Green function) methods. The studied molecule comprises three 2-methoxyethoxy groups (-O-CH2-CH2-O-CH3) connected to a central boron atom, which results in the C3-symmetry of the compound. The resulting anion was stable against fragmentation processes and its vertical electron detachment energy was found to be 5.72 eV. Due to its equilibrium structure resembling that of classical tripodal podands, the [F-B(O-CH2-CH2-O-CH3)3]− anion is capable of binding metal cations using its three arms, and thus may form strongly bound ionic complexes such as [F-B(O-CH2-CH2-O-CH3)3]−/Li+ and [F-B(O-CH2-CH2-O-CH3)3]−/Mg2+. The binding energies predicted for such compounds far exceed those of the similar neutral classical podand ligands, which likely makes the [F-B(O-CH2-CH2-O-CH3)3]− system a more effective molecular trap or steric shielding agent with respect to selected metal cations.

Structures and Superhalogen Properties of Pt2Cl n (2 ≤ n ≤ 10) Clusters

Laser ablation mass spectrometry was applied to study the cluster anions of Pt₂Cl _n^-. Among them, Pt₂Cl₆^- and Pt₂Cl₉^- were observed with remarkable intensities in the mass spectrum. Collision-activated dissociation experiments were also performed for the two anions. A systematic study of the structures and electron affinities (EAs) of Pt_1-2Cl _n (2 ≤ n ≤ 10) clusters was performed on the level of B3LYP/Lanl2dz/6-311++G(2d, p). For both systems, their EAs do not increase monotonically with the increase of Cl atoms. All the clusters of PtCl _n (3 ≤ n ≤ 10) and Pt₂Cl _n (3 ≤ n ≤ 10) show EAs larger than that of the Cl atom. The highest EAs for the series of Pt₂Cl _n and PtCl _n are 6.55 and 5.82 eV, corresponding to those of Pt₂Cl₉ and PtCl₉, respectively. The results indicate that these clusters might be applied as effective units in constructing new "hypersalts".