Classically closo-carborane anions, particularly [HCB11H11]− and [HCB9H9]−, and their derivatives have primarily been used as weakly coordinating anions to isolate reactive intermediates, platforms for stoichiometric and catalytic functionalization, counteranions for simple Lewis acid catalysis, and components of materials like liquid crystals. The aim of this article is to educate the reader on the contemporary nonclassical applications of these anions. Specifically, this review will cover new directions in main group catalysis utilized to achieve some of the most challenging catalytic reactions such as C–F, C–H, and C–C functionalizations that are difficult or impossible to realize with transition metals. In addition, the review will cover the utilization of the clusters as dianionic C σ-bound ligands for coordination chemistry, ligand substituents for coordination chemistry and advanced catalyst design, and covalently bound spectator substituents to stabilize radicals. Furthermore, their applications as solution-based and solid-state electrolytes for Li, Na, and Mg batteries will be discussed.

Here we apply microcrystal electron diffraction (MicroED) to the structural determination of transition-metal complexes. We find that the simultaneous use of 300 keV electrons, very low electron doses, and an ultrasensitive camera allows for the collection of data without cryogenic cooling of the stage. This technique reveals the first crystal structures of the classic zirconocene hydride, colloquially known as “Schwartz’s reagent”, a novel Pd(II) complex not amenable to solution-state NMR or X-ray crystallography, and five other paramagnetic and diamagnetic transition-metal complexes.

Electrochemical systems offer a versatile means for creating adaptive devices. However, the utility of electrochemical deposition is inherently limited by the properties of the electrolyte. The development of ionic liquids enables electrodeposition in high-vacuum environments and presents opportunities for creating electrochemically adaptive and regenerative spacecraft components. In this work, we developed a silver-rich, boron cluster ionic liquid (BCIL) for reversible electrodeposition of silver films. This air and moisture stable electrolyte was used to deposit metallic films in an electrochemical cell to tune the emissivity of the cell in situ, demonstrating a proof-of-concept design for spacecraft thermal control.

Abstract:In 1994 Reed and co-workers reported a variety of trityl salts with various functionalized icosahedral carborane anions. However, it was mentioned that the parent carba-closododecaborate anion [HCB 11 H 11 ] -underwent an unidentified chemical reaction with the trityl cation as the ion pair formed in solution. In this communication, we have reexamined this reaction and identified the reaction as classical electrophilic

The synthesis and ethylene reactivity of the zwitterionic Pd methyl complexes (κ 2 -P,Cl-PR 2 CB 9 Cl 9 )PdMe-(THF) (7, R = i Pr; 8, R = Ph) and (κ 2 -P,O-P(o-OMe-Ph) 2 CB 9 Cl 9 )PdMe(THF) (9), which contain the first phosphines appended with anionic 10-vertex perchlorinated closo-carboranes, are described. Complexes 7 and 8 oligomerize ethylene (23 °C, 2 atm) to a Schulz−Flory distribution of C 4 −C 10 olefins with TOFs of ca. 8000 and 1800 t.o./h, respectively. 8 is ca. 4 times more active than the analogous (κ 2 -P,F-ortho-PPh 2 C 6 H 4 BF 3 )PdMe(L) (L = pyridine or collidine) system reported by Jordan and Piers, which produces butenes. Complex 9 reacts with ethylene to yield polyethylene wax (M n ca. 1000, Đ ca. 1.5) that is similar to commercial Fischer−Tropsch waxes. The activities of 7−9 are independent of ethylene pressure and the presence of B(C 6 F 5 ) 3 , suggesting that the catalyst resting state is the corresponding (PR 2 CB 9 Cl 9 )PdR(H 2 CCH 2 ) adduct. The molecular weights of the oligomer/polymer products are independent of ethylene pressure, which is consistent with an associative chain transfer mechanism. Reaction of 9 with ethylene generates the corresponding ethylene complex (κ 2 -P,O-P(o-OMe-Ph) 2 CB 9 Cl 9 )PdMe(H 2 CCH 2 ), which inserts ethylene at −20 °C with a barrier (ΔG ⧧ insertion ) of 18.1 kcal/mol.