Features of Protonation of the Simplest Weakly Basic Molecules, SO₂, CO, N₂O, CO₂, and Others by Solid Carborane Superacids

Abstract

An experimental study on protonation of simple weakly basic molecules (L) by the strongest solid superacid, H(CHB F ), showed that basicity of SO is high enough (during attachment to the acidic H atoms at partial pressure of 1 atm) to break the bridged H-bonds of the polymeric acid and to form a mixture of solid mono- LH ⋅⋅⋅An , and disolvates, L-H -L. With a decrease in the basicity of L=CO (via C), N O, and CO (via O), only proton monosolvates are formed, which approach L-H -An species with convergence of the strengths of bridged H-bonds. The molecules with the weakest basicity, such as CO and weaker, when attached to the proton, cannot break the bridged H-bond of the polymeric superacid, and the interaction stops at stage of physical adsorption. It is shown here that under the conditions of acid monomerization, it is possible to protonate such weak bases as CO , N , and Xe.

Silylium Ions: From Elusive Reactive Intermediates to Potent Catalysts

“…311 However, a reinvestigation by Stoyanov suggest that the CO 2 is more likely physically adsorbed by the carborate acid. 312 It should be noted here that the conjugate acid of the [B(C 6 F 5 ) 4 ] − anion does not exist due to the lability of the B−C linkage of the tetraaryl borate under highly acidic conditions. 303,304 In closely related reactions, strong alkylating agents can be prepared from carborate-stabilized silylium ions by the reaction with alkyl triflates such as MeOTf (Scheme 39, top).…”

A Stable Crystalline Copper(I)–N2O Complex Stabilized as the Salt of a Weakly Coordinating Anion

“…[4,5] Simultaneously,nitrous oxide exhibits kinetic stability that renders this highly oxidizing and thermodynamically unstable molecule (in respect to decomposition to N 2 and O 2 )v ery difficult to activate under mild conditions.T he feature is ar esult of high HOMO-LUMO gap,l ow-lying HOMO level (ionization energy of about 12.8 eV) and as mall dipole moment of N 2 O. [5,6] As ac onsequence,t he molecule is also ap oor ligand, and condensed phase systems known to bind it are uncommon and include for example,z eolites, [7] frustrated Lewis pairs, [8] NHC-based compounds, [9] H(CHB 11 F 11 ), which protonates N 2 O, [10] and just three well-defined metal complexes. [11,12] Among these, only one metal-N 2 Ocomplex (with aV III center,that is,ad 2 system) has been structurally characterized to date.…”

Icosahedral Carborane Superacids and their Conjugate Bases Comprising H, F, Cl, and CN Substituents: A Theoretical Investigation of Monomeric and Dimeric Cages

“…Recent experimental and theoretical investigations concerning functionalized carborane acids include, among others, the electronic structure studies of variously substituted carborane acids and their conjugate bases, [51,52] the discussion of stabilities of tetravalent oxygen and sulfur centers (e. g., in various dications such as H(CH 3 ) 3 O 2 + ) in complexes with H(CHB 11 F 11 ), [53] demonstration of the catalytic activity of various carborane acids (fluorinated, chlorinated, and brominated) in alcohol dehydration reactions, [54] and the experimental demonstration that even weak bases such as CO 2 or N 2 might be protonated by certain carborane acids (under the condition of acid monomerization). [55] The main goal of our studies was to investigate the highsymmetry quasi-icosahedral carborane superacids utilizing electronegative F, Cl, and CN substituents and predict their acid strength as well as the electronic stabilities (manifested by the values of vertical excess electron detachment energies) of their conjugate bases (i. e., the anions resulting from deprotonation thereof).…”

“…The properties of various carborane acids (including the H(CHB 11 Cl 11 ) acid considered the strongest isolable acid both in gas phase and solution) are the subject of ongoing theoretical and experimental studies, however, it seems likely that many of the systems whose structure involves the icosahedral carborane core are yet to be discovered. Recent experimental and theoretical investigations concerning functionalized carborane acids include, among others, the electronic structure studies of variously substituted carborane acids and their conjugate bases, the discussion of stabilities of tetravalent oxygen and sulfur centers (e. g., in various dications such as H(CH 3 ) 3 O 2+ ) in complexes with H(CHB 11 F 11 ), demonstration of the catalytic activity of various carborane acids (fluorinated, chlorinated, and brominated) in alcohol dehydration reactions, and the experimental demonstration that even weak bases such as CO 2 or N 2 might be protonated by certain carborane acids (under the condition of acid monomerization) …”