Properties of perhalogenated {closo-B₁₀} and {closo-B₁₁} multiply charged anions and a critical comparison with {closo-B₁₂} in the gas and the condensed phase

Abstract

Dependence of electronic properties and reactivity of closo-borates with size and halogen substituent was investigated.

Properties of gaseous closo-[B6X6]2− dianions (X = Cl, Br, I)

“…[1][2][3][4] [B 12 (CN) 12 ] 2À is the most electronically stable multiply charged anion (MCA) synthesized so far [5][6][7][8] and [B 12 I 12 ] 2À belongs to the most chaotropic anions known. 9 Understanding interactions of the weakly coordinating [B 12 X 12 ] 2À anions with different counterions, 1,2,[10][11][12] solvent molecules, 13 coordinating neutral species, 14 host molecules in supramolecular complexes, [15][16][17] and biomolecules 18,19 is of interest, for example, to boron neutron capture therapy, 20,21 stabilization of reactive cations in synthesis and catalysis, 1,4 battery science, 22 and non-linear optics. 21 A systematic study of the molecular properties of closo-[B n X n ] 2À dianions and their dependence on the substituent X and scaffold size n constitutes the scientific foundation for the rational design of closo-borate anions for specific applications.…”

“…Several gas phase studies have examined the reactivity and electronic structure of [B 12 X 12 ] 2À (X = H, F, Cl, Br, I, CN), 5,[26][27][28][29] [B 11 X 11 ] 2À and [B 10 X 10 ] 2À (X = Cl, Br, I). 10 Much less is known about smaller closo-borate dianions. 30 However, the chemistry of hexaborate dianions has recently received a renewed interest [31][32][33] and their salts have been discussed in the context of hydrogen storage.…”

Measuring Electronic Structure of Multiply Charged Anions to Understand Their Chemistry: A Case Study on Gaseous Polyhedral closo-Borate Dianions

“…Interestingly, despite identical gas-phase electronic stability for [B 11 X 11 ] 2− and [B 10 X 10 ] 2− , the measured E 1/2 value of the former is lower than the E 1/2 value of the latter (in all X cases). 25 The lower stability of [B 11 X 11 ] 2− compared to [B 10 X 10 ] 2− in CV experiments suggests stronger solvent stabilization in the [B 10 X 10 ] 2− case and illustrates the important role of solvation at play to determine the electrochemistry of redox species. closo-Dodecaborates are superchaotropic anions.…”

“…High structural fluxionality has been evidenced for [closo-B 11 H 11 ] 2− , which shows a rapid interconversion of the 11 boron vertices. 25 Connecting closo-borate anions to organic/ biomolecules is important to medical research like boron neutron capture therapy (BNCT). 44−46 An interesting approach may be the formation of inclusion complexes.…”

“…The two excess negative charges are stabilized in a delocalized σ-electron system within the boron cage to satisfy the Wade–Mingos rules . Different closo -borate anions with the general formula [ closo -B n X n ] 2– have been observed with the boron cage size ranging from n = 6 to 12, − among which the hexa- ( n = 6), deca- ( n = 10), and dodecaborate ( n = 12) anions possess the most stable boron core structures with high symmetry (see Figure ). Substituting H atoms in the quintessential precursor [B 12 H 12 ] 2– with monovalent ligands X, including halides F–I, OH, OR, CH 3 , and CN, leads to a series of dodecaborate derivatives with very different electronic stabilities.…”