Oxidation von closo-[B12Cl12]2− zum Radikalanion [B12Cl12].− und zum neutralen B12Cl12

Synthesis, Electronic Properties and Reactivity of [B12 X11 (NO2 )]2- (X=F-I) Dianions

Nitro‐functionalized undecahalogenated closo‐dodecaborates [B₁₂X₁₁(NO₂)]²⁻ were synthesized in high purities and characterized by NMR, IR, and Raman spectroscopy, single crystal X‐diffraction, mass spectrometry, and gas‐phase ion vibrational spectroscopy. The NO₂ substituent leads to an enhanced electronic and electrochemical stability compared to the parent perhalogenated [B₁₂X₁₂]²⁻ (X=F–I) dianions evidenced by photoelectron spectroscopy, cyclic voltammetry, and quantum‐chemical calculations. The stabilizing effect decreases from X=F to X=I. Thermogravimetric measurements of the salts indicate the loss of the nitric oxide radical (NO^.). The homolytic NO^. elimination from the dianion under very soft collisional excitation in gas‐phase ion experiments results in the formation of the radical [B₁₂X₁₁O]^2−.. Theoretical investigations suggest that the loss of NO^. proceeds via the rearrangement product [B₁₂X₁₁(ONO)]²⁻. The O‐bonded nitrosooxy structure is thermodynamically more stable than the N‐bonded nitro structure and its formation by radical recombination of [B₁₂X₁₁O]^2−. and NO^. is demonstrated.

Boron: Its Role in Energy-Related Processes and Applications

Boron's unique position in the Periodic Table, that is, at the apex of the line separating metals and nonmetals, makes it highly versatile in chemical reactions and applications. Contemporary demand for renewable and clean energy as well as energy-efficient products has seen boron playing key roles in energy-related research, such as 1) activating and synthesizing energy-rich small molecules, 2) storing chemical and electrical energy, and 3) converting electrical energy into light. These applications are fundamentally associated with boron's unique characteristics, such as its electron-deficiency and the availability of an unoccupied p orbital, which allow the formation of a myriad of compounds with a wide range of chemical and physical properties. For example, boron's ability to achieve a full octet of electrons with four covalent bonds and a negative charge has led to the synthesis of a wide variety of borate anions of high chemical and electrochemical stability-in particular, weakly coordinating anions. This Review summarizes recent advances in the study of boron compounds for energy-related processes and applications.

Teaching an old dog new tricks: new directions in fundamental and applied closo-carborane anion chemistry

In this feature article we cover new directions in the fundamental and applied chemistry of the closo-carborane anions [HCB₁₁H₁₁]⁻¹ and [HCB₉H₉]⁻¹, including energy storage applications, ionic liquids, anionic carborane fused heterocycles/radicals, ligand substituents, and ligands for catalysis and coordination chemistry.

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

This Review gives a comprehensive overview of the most topical weakly coordinating anions (WCAs) and contains information on WCA design, stability, and applications. As an update to the 2004 review, developments in common classes of WCA are included. Methods for the incorporation of WCAs into a given system are discussed and advice given on how to best choose a method for the introduction of a particular WCA. A series of starting materials for a large number of WCA precursors and references are tabulated as a useful resource when looking for procedures to prepare WCAs. Furthermore, a collection of scales that allow the performance of a WCA, or its underlying Lewis acid, to be judged is collated with some advice on how to use them. The examples chosen to illustrate WCA developments are taken from a broad selection of topics where WCAs play a role. In addition a section focusing on transition metal and catalysis applications as well as supporting electrolytes is also included.

Protic anions [H(B12X12)]- (X = F, Cl, Br, I) that act as Brønsted acids in the gas phase

The acidity of protic cations and neutral molecules has been studied extensively in the gas phase, and the gas-phase acidity has been established previously as a very useful measure of the intrinsic acidity of neutral and cationic compounds. However, no data for any anionic acids were available prior to this study. The protic anions [H(B12X12)](-) (X = F, Cl, Br, I) are expected to be the most acidic anions known to date. Therefore, they were investigated in this study with respect to their ability to protonate neutral molecules in the gas phase by using a combination of mass spectrometry and quantum-chemical calculations. For the first time it was shown that in the gas phase protic anions are also able to protonate neutral molecules and thus act as Brønsted acids. According to theoretical calculations, [H(B12I12)](-) is the most acidic gas-phase anion, whereas in actual protonation experiments [H(B12Cl12)](-) is the most potent gas-phase acidic anion for the protonation of neutral molecules. This discrepancy is explained by ion pairing and kinetic effects.

Boron clusters as highly stable magnesium-battery electrolytes

Boron clusters are proposed as a new concept for the design of magnesium-battery electrolytes that are magnesium-battery-compatible, highly stable, and noncorrosive. A novel carborane-based electrolyte incorporating an unprecedented magnesium-centered complex anion is reported and shown to perform well as a magnesium-battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium-battery electrolytes is very high.