Knowra Carborane acid Carborane acid Carborane acids are superacids whose conjugate bases are exceptionally weakly coordinating carborane anions. They can protonate substances that resist protonation by conventional mineral acids.
Carborane anion : A negatively charged cluster ion built from boron, carbon, and hydrogen atoms, with charge spread across its structure. Its diffuse charge makes it unusually reluctant to bind the protonated substrate.
Icosahedral molecular geometry : A three-dimensional arrangement with twelve vertices and twenty triangular faces. Many carborane cages adopt this geometry, distributing charge across a compact cluster.
Tertiary carbocations : Positively charged carbon species in which the charged carbon is bonded to three carbon groups. Carborane acids can generate and stabilize highly reactive carbocations with little anion capture.
Christopher A. Reed : An American chemist known for research on superacids, weakly coordinating anions, and reactive cations. His group developed and characterized carborane acids as exceptionally strong, nonoxidizing proton donors.
Triflic acid : A strong sulfonic acid, CF₃SO₃H, whose conjugate base is the triflate ion. Triflic acid is a familiar strong acid, but is substantially less acidic than the strongest carborane acids.
Weakly coordinating anion : An anion that interacts only weakly with positively charged species, leaving their reactivity comparatively unobstructed. This behavior explains why carborane acid's conjugate base does not suppress strong acidity.
Closo-carborane : A closed polyhedral cluster of boron and carbon atoms with a delocalized bonding framework. Closo cages provide the stable anionic frameworks used in prominent carborane acids.
Silylium ion : A positively charged silicon species with three substituents and an electron-deficient center. Weakly coordinating carborane anions permit isolation of otherwise highly reactive silylium ions.
Weakly coordinating anion chemistry : The study and use of anions that minimize binding to cations and other electrophilic species. Carborane acids grew from strategies for separating reactive cations from interfering counterions.
Sulfuric acid : A diprotic mineral acid with formula H₂SO₄, widely used in industry and laboratory chemistry. It anchors the conventional superacid definition that carborane acids greatly exceed.
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