With the aid of ab initio calculations at the MP2 level of theory, we designed a novel class of inorganic salts, M(+)(en)3M3'O(-) (M, M' = Li, Na, and K), by using the M3'O superalkalis. These compounds are the first examples of inorganic salts wherein the superalkali occupies the anionic site, and termed superalkalides. The electronic structural features of the M(+)(en)3M3'O(-) superalkalides are very similar to those of the corresponding M(+)(en)3M'(-) alkalides which have been reported by Zurek (J. Am. Chem. Soc., 2011, 133, 4829). In this study, the calculated NLO properties of M(+)(en)3M3'O(-) and M(+)(en)3M'(-) (M, M' = Li, Na, and K) show that both superalkalides and alkalides have significantly large first hyperpolarizabilities (β0) with the values in the range of 7.80 × 10(3) to 9.16 × 10(4) a.u. and 7.95 × 10(3) to 1.84 × 10(5) a.u., respectively. Computations on the stabilities of M(+)(en)3M3'O(-) and M(+)(en)3M'(-) demonstrate that the M(+)(en)3M3'O(-) superalkalides are preferably stable than the corresponding M(+)(en)3M'(-) alkalides because of the presence of hydrogen bonds in M(+)(en)3M3'O(-). Therefore, the designed superalkalides, M(+)(en)3M3'O(-) (M, M' = Li, Na, and K), with excellent nonlinear optical properties and high stabilities are greatly promising candidates for NLO materials. We hope that this article could attract more research interest in superatom chemistry and for further experimental research.

MXene-derived nanostructures provide the possibility of meeting the requirements of strong absorption, thin thickness and flexible layer for electromagnetic (EM) wave absorption. However, exploration of pure and well-intercalated MXene nanosheets for efficient EM wave absorption is still in the nascent stages. Herein, TiCT nanosheets with solvent-manipulated properties were achieved via ultrasonication-solvothermal treatment of bulk TiCT in different solvents including dimethylformamide (DMF), ethanol, and dimethyl sulfoxide (DMSO), respectively, because of their combined influences of molecular size, oxidation capability, and boiling point. Especially, it was found that a larger layer space and less oxidation effects on the TiCT nanosheets were observed upon solvothermal treatment in DMF than those in ethanol or DMSO treatment. As a result, the DMF-treated TiCT nanosheets can be used as highly effective dielectric materials for EM wave absorption. The reflection loss value reached -41.9 dB (more than 99.99%) at 13.4 GHz with the sample thickness of only 1.1 mm. Characterization techniques including scanning electron microscopy, transmission electron microscopy, atomic force microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and density functional theory calculation were used to elaborate the possible mechanisms.

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Three sizes of atomically precise tiara-like structural Nin(SR)2n (n = 4, 5 and 6) are co-synthesized by a one-pot method and isolated using thin layer chromatography. The molecular formulas of Ni5(SR)10 and Ni6(SR)12 are determined using matrix-assisted laser desorption ionization mass spectrometry, and the tiara-like structures of Ni4(SR)8 and Ni6(SR)12 are proved using single-crystal X-ray crystallography. Nuclear magnetic resonance shows that Ni5(SR)10 has a similar tiara-like structure too. The electrochemical gap enlarges with the increase of the cluster size, which agrees with the calculated HOMO-LUMO gap and optical gap by TD-DFT, but the experimental optical gap is GO(Ni4(SR)8) > GO(Ni6(SR)12) > GO(Ni5(SR)10) due to Ni4(SR)8 owning a pseudo-optical gap at 2.0 eV.

A nickel-nickel-bonded complex, [{Ni(μ-L(.-))}2] (1; L=[(2,6-iPr2C6H3)NC(Me)]2), was synthesized from reduction of the LNiBr2 precursor by sodium metal. Further controllable reduction of 1 with 1.0, 2.0 and 3.0 equiv of Na, respectively, afforded the singly, doubly, and triply reduced compounds [Na(DME)3]·[{Ni(μ-L(.-))}2] (2; DME=1,2-dimethoxyethane), [Na(Et2O)]Na[(L(.-))Ni-NiL(2-)] (3), and [Na(Et2O)]2Na[L(2-)Ni-NiL(2-)] (4). Here L represents the neutral ligand, L(.-) denotes its radical monoanion, and L(2-) is the dianion. All of the four compounds feature a short Ni-Ni bond from 2.2957(6) to 2.4649(8) Å. Interestingly, they display two different structures: the perpendicular (1 and 2) and the coaxial (3 and 4) structure, in which the metal-metal bond axis is perpendicular to or collinear with the axes of the α-diimine ligands, respectively. The electronic structures, Ni-Ni bonding nature, and energetic comparisons of the two structure types were investigated by DFT computations.

Combined DFT and FTIR investigations reveal interesting hydrogen bonding interactions between dimethyl sulfoxide and an ether-functionalized imidazolium-based ionic liquid.

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