Structures and electron affinities of the di‐arsenic fluorides As₂F_n/As₂F (n = 1–8)

Abstract

Developments in the preparation of new materials for microelectronics are focusing new attention on molecular systems incorporating several arsenic atoms. A systematic investigation of the As2Fn/As2Fn- systems was carried out using Density Functional Theory methods and a DZP++ quality basis set. Global and low-lying local geometric minima and relative energies are discussed and compared. The three types of neutral-anion separations reported in this work are: the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). Harmonic vibrational frequencies pertaining to the global minimum for each compound are reported. From the first four studied species (As2Fn, n=1-4), all neutral molecules and their anions are shown to be stable with respect to As-As bond breaking. The neutral As2F molecule and its anion are predicted to have Cs symmetry. We find the trans F-As-As-F isomer of C2h symmetry and a pyramidalized vinylidene-like As-As-F2- isomer of Cs symmetry to be the global minima for the As2F2 and As2F2- species, respectively. The lowest lying minima of As2F3 and As2F3- are vinyl radical-like structures F-As-As-F2 of Cs symmetry. The neutral As2F4 global minimum is a trans-bent (like Si2H4) F2-As-As-F2 isomer of C2 symmetry, while its anion is predicted to have an unusual fluorine-bridged (C(1)) structure. The global minima of the neutral As2Fn species, n=5-8, are weakly bound complexes, held together by dipole-dipole interactions. All such structures have the AsFm-AsFn form, where (m,n) is (2,3) for As2F5, (3,3) for As2F6, (4,3) for As2F7), and (5,3) for As2F8. For As2F8 the beautiful pentavalent F4As-AsF4 structure (analogous to the stable AsF5 molecule) lies about 30 kcal/mol above the AsF3 . . . AsF5 complex. The stability of AsF(5) depends crucially on the strong As-F bonds, and replacing one of these with an As-As bond (in F4As-AsF4) has a very negative impact on the molecule's stability. The anions As2Fn-, n=5-8, are shown to be stable with respect to the As-As bond breaking, and we predict that all of them have fluorine-bridged or fluorine-linked structures. The zero-point vibrational energy corrected adiabatic electron affinities are predicted to be 2.28 eV (As2F), 1.95 eV (As2F2), 2.39 eV (As2F3), 1.71 eV (As2F4), 2.72 eV (As2F5), 1.79 eV (As2F6), 5.26 eV (As2F7), and 3.40 eV (As2F8) from the BHLYP method. Vertical detachment energies are rather large, especially for species with fluorine-bridged global minima, having values up to 6.45 eV (As2F7, BHLYP).

Probing the Electronic Structure and Property of Neutral and Charged Arsenic Clusters (Asn(+1,0,–1), n ≤ 8) Using Gaussian-3 Theory

“…Over the past two decades, the compounds of arsenic have been studied experimentally and theoretically because they have been used as pigments since ancient times and used as components to modify the mechanical properties of lead and copper alloys and to eliminate unwanted coloration of glasses in modern industries. , The arsenic clusters have played prominent roles not only in the early development of both forensics and chemotherapy but also in many different fields of modern science, such as solid-state physics, biochemistry, physical chemistry, surface phenomena, and catalysis. − The knowledge of the fundamental properties, such as the ground and low-lying electronic states of neutral and charged arsenic clusters, electron affinities (EAs), and ionization potentials (IPs), should lead to a more complete understanding of their role in many different fields. With this motivation, we have carried out a detailed study of the structures and properties of neutral and charged arsenic clusters by means of the higher level of the Gaussian-3 (G3) theory. , …”

Franck–Condon simulation of the photoelectron spectrum of AsF2 and the photodetachment spectrum of AsF2− using ab initio calculations: Ionization energy and electron affinity of AsF2

“…4 In this connection, arsenic fluorides have received some attention because of their importance in the semiconductor industry. [5][6][7] However, there have been very few spectroscopic and computational studies on AsF 2 , its cation and anion, and the ionization energy and electron affinity of AsF 2 are not well established. Specifically, there are three spectroscopic studies on, or related to, AsF 2 .…”

Probing the Electronic Structures and Properties of Neutral and Charged Monomethylated Arsenic Species (CH3Asn(−1,0,+1), n = 1–7) Using Gaussian-3 Theory

“…The equilibrium geometries of the CH 3 As 2 compounds and their charged species are given in Figure . Similarly to As 2 F compound, the lowest-energy structures of neutral CH 3 As 2 are C s symmetry with 2 A′ ground state (denoted 2a ). The bond lengths are predicted to be 1.990 Å for As–C bonds and 1.090–1.092 Å for three C–H bonds, and the bond angles are predicted to be 101.1° for As2–As1–C with the MP2(full)/6-31G(d) scheme.…”