Dianionic Tetraborates Do Exist as Stable Entities

Abstract

To date, B(6)H(6)(2-) and some of its derivatives are the smallest members of the closo-borates that have been synthesized and analyzed in condensed phases. In contrast, no stable dianionic tetraborate has yet been observed, either in solution or solids or in the gas phase. In this work, the gas-phase stability of dianionic tetraborates B(4)X(4)(2-) (X = H, CN, NC, or BO) is investigated with ab initio methods. For this objective, the geometries of the dianions are optimized, the electronic stability is tested, and various fragmentation channels are studied. In agreement with previous examinations, tetrahedral isomers of all examined tetraborates have been found to represent geometrically stable isomers and to exhibit a triplet electronic ground state. However, these isomers are electronically unstable, i.e., their additional electrons are not bound. Furthermore, new D(2)(d)()-symmetric isomers of B(4)X(4)(2-) (X = H, CN, NC, or BO) have been identified that have a closed-shell singlet ground state and are lower in energy than their tetrahedral counterparts. Moreover, B(4)(CN)(4)(2-) and B(4)(BO)(4)(2-) represent stable gas-phase dianions and are predicted to be observable in suitable experiments. The electronic properties and geometries of these dianions are discussed in detail and explained in terms of the electrostatic repulsion of the excess electrons and the aromaticity of the dianions.

Deciphering chemical bonding in BnHn2−(n = 2–17): flexible multicenter bonding

“…The B n H n 2À (n ¼ 6-12) and (n ¼ 4, 5, 13-17) have been observed experimentally and investigated theoretically, respectively. [51][52][53][54][55]81,82 In order to grasp the structural features and assure the integrity in this family, B n H n 2À with n ¼ 2 and 3 are considered as well. The structures of borane dianions are taken from the previous studies of Lipscomb, Schleyer, Dreuw, and their co-workers.…”

STRUCTURE AND STABILITY OF MONOCYCLIC $({\rm CH})_{4-n} ({\rm BL})_{n}^{2-}$(L = CO, N2, CS) DIANIONS AND THEIR DILITHIUM COMPLEXES

“…6,8 Inspired by the theoretical results on C 4 H 2− 4 , homo-, 1,3-heteronuclear, and inorganic four-memberedring systems with 6π electrons were studied to determine their structure, stability, and aromaticity. 9, 10 The planar cyclotetraphosphide (P 2− 4 ) structure has been confirmed by experiment and theory, and is considered to be aromatic. 11 Recently, the (SiR) 2− 4 dianion has been found as a new ligand for transition metal complexes.…”

Substituent‐Stabilized Organic Dianions in the Gas Phase and Their Potential Use as Electrolytes in Lithium‐Ion Batteries

“…studied the stability of B 6 H 6 2− by substituting the H atoms with groups such as F, Cl, CN, NC or BO, which resulted in stable dianions in the gas phase . Similar studies have also been performed for the penta‐ and tetraborate dianions B 5 X 5 2− and B 4 X 4 2− . The role of substituents in enhancing the stability of multiply charged species in the gas phase was recently studied by substituting H atoms in B 12 H 12 2− by CN moieties.…”

“…[8] Similar studies have also been performed for the penta-and tetraborate dianions B 5 X 5 2À and B 4 X 4 2À . [9,10] The role of substituents in enhancing the stability of multiply charged speciesi nt he gas phase was recently studied by substituting Ha toms in B 12 cluster was found to be unusually stable with the second electron bound by 5.3 eV,w hich is almost six times largert han that in the B 12 H 12 2À dianion. [11] The powero fs ubstituent engineering was further demonstrated when aBatom in the cage was replaced by aCatom, to form CB 11 (CN) 12 2À .I tw as found that CB 11 (CN) 12 2À is also stable, whereas its isoelectronic analogue CB 11 H 12 2À is unstable.…”