On golden bond: In both the solid state and in solution, the neutral dinuclear gold(I) complexes [12‐(R3PAu)2CC‐closo‐1‐CB11H11] (R=Me, Et) dimerize to tetranuclear gold(I) clusters held together by aurophilic interactions. For the Et3P complex, the dimer and the monomer exist in equilibrium in solution at 25 °C. In contrast, even at 75 °C only dimers (AuI4 clusters), are observed for the Me3P complex (see structure: C black, B brown, P pink, Au yellow).

The range of electrochemical stability of a series of weakly coordinating halogenated (Hal=F, Cl, Br, I) 1-carba-closo-dodecaborate anions, [1-R-CB(11)X(5)Y(6)](-) (R=H, Me; X=H, Hal, Me; Y=Hal), has been established by using quantum chemical calculations and electrochemical methods. The structures of the neutral and dianionic radicals, as well as the anions, have been optimized by using DFT calculations at the PBE0/def2-TZVPP level. The calculated structures are in good agreement with existing experimental data and with previous calculations. Their gas-phase ionization energies and electron affinities were calculated based on their optimized structures and were compared with experimental (cyclic and square-wave) voltammetry data. Electrochemical oxidation was performed in MeCN at room temperature and in liquid sulfur dioxide at lower temperatures. All of the anions show a very high resistance to the onset of oxidation (2.15-2.85 V versus Fc(0/+)), with only a minor dependence of the oxidation potential on the different halogen substituents. In contrast, the reduction potentials in MeCN are strongly substituent dependent (-1.93 to -3.32 V versus Fc(0/+)). The calculated ionization energies and electron affinities correlate well with the experimental redox potentials, which provide important verification of the thermodynamic validity of the mostly irreversible redox processes that are observed for this series. The large electrochemical windows that are afforded by these anions indicate their suitability for electrochemical applications, for example, as supporting electrolytes.

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The diethynyldicarba‐closo‐dodecaboranes 1,2‐R2‐9,12‐(HCC)2‐closo‐1,2‐C2B10H8 [R = H (1a), Me (2a)] and 9,10‐(HCC)2‐closo‐1,7‐C2B10H10 (3a) were obtained by Pd‐catalyzed Kumada‐type cross‐coupling reactions of the corresponding diiodinated dicarba‐closo‐dodecaboranes withMe3SiCCMgBr followed by desilylation of the trimethylsilylalkynyl‐substituted clusters. In addition, the related {closo‐C2B10} derivatives with one ethynyl group 1,2‐R‐9‐HCC‐closo‐1,2‐C2B10H9 [R = H (4a), Me (5a)], 9‐HCC‐closo‐1,7‐C2B10H11 (6a), and 2‐HCC‐closo‐1,12‐C2B10H11 (7a) were synthesized and their spectroscopic properties were compared to those of the diethynyl‐substituted {closo‐C2B10} clusters. The ethynyl‐ and trimethylsilylalkynyl‐functionalized dicarba‐closo‐dodecaboranes were characterized by elemental analysis, mass spectrometry, as well as by multinuclear NMR, IR, and Raman spectroscopy. The assignment of the NMR spectroscopic chemical shifts and the IR and Raman bands is supported by theoretical values derived from density functional calculations. The crystal structures of 9,12‐(HCC)2‐closo‐1,2‐C2B10H10 (1a), 9,10‐(HCC)2‐closo‐1,7‐C2B10H10 (3a), and 1,2‐Me‐9,12‐(Me3SiCC)2‐closo‐1,2‐C2B10H8 (2b) were determined by single‐crystal X‐ray diffraction. Selected experimental bond properties are compared to bond lengths and angles calculated at the B3LYP/6‐311++G(d,p) level of theory.

The coordination of acetonitrile and water to the Hg atom in [Hg(closo-1-CB(11)F(11))(2)](2-) (1) reveals the Lewis acidity of the Hg(II) center, which is unprecedented, since 1 is a dianion. Both coordination compounds were characterized by single-crystal X-ray diffraction, vibrational spectroscopy, and differential scanning calorimetry (DSC). In contrast, the Hg atom in [PhHg(closo-1-CB(11)F(11))](-) (2) does not coordinate to CH(3)CN and H(2)O, although it has only a single negative charge.