In view of the strong electron-donating nature of H(-) and extensive vacancy formation in metals by hydrogen insertion, a series of LnH2+x (Ln = La, Ce, or Y) compounds with fluorite-type structures were verified to be the first hydride-based electride, where itinerant electrons populating the cage are surrounded by H(-) anions. The electron transfer into the cage probably originates from Ln-cage covalent interaction. To the best of our knowledge, anion-rich electrides are extremely rare, and a key requirement for their formation is that the cage site is not occupied by lone pair electrons of the adjacent ions. In the case of LnH2, the cage site is surrounded by eight H(-) anions with isotopic electronic character caused by the lack of mixing of H p-orbital character. Notably, Ru-loaded LnH2+x electride powders synthesized by hydrogen embrittlement (Ln = La or Ce) were found to work as efficient catalysts for ammonia synthesis at ambient pressure, without showing serious signs of hydrogen poisoning. There are several possible origins of the observed high catalytic activity in the hydride promotors: the small work function of LnH2+x derived from the covalent interaction between Ln cation and the H(-) σ donor, and the formation of Ln nitride during catalytic reaction.

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A new method of measuring second-harmonic generation (SHG) efficiency using powder crystals is proposed. The second harmonic, which is generated by the evanescent wave under total reflection conditions, is phase matched for every element of the second-order optical nonlinear coefficient, whether each element is phase matchable in a bulk crystal or not. Observing this phase-matched second-harmonic power gives the SHG efficiency, regardless of the phase matchability in a bulk crystal, even if powder crystals are used as a sample.

Cationic palladium(II) complexes of the di-t-butylnitroxide radical, [Pd(But2NO)(L-L)]X (L-L=2,2′-bipyridine, 1,10-phenanthroline, N-substituted 2-pyridylmethyleneamine and bis(triphenylphosphine); X−=ClO4-and/or BPh4−), were prepared. 1H NMR spectra of the complexes indicate that the nitroxide forms a three membered ring with the palladium atom. The N-methyl- and N-ethyl-2-pyridylmethyleneamine complexes exist as two geometrical isomers in solution, whose ratios are 1 : 1 and 1 : 0.2, respectively. In the N-butyl and N-p-tolyl analogs, however, only one of the isomers exists in solution. These results are interpreted in terms of steric repulsion between the t-butyl groups and N-substituents. The bipyridine complex reacts with dialkyl disulfides in the presence of catalytic amounts of bipyridine to give a sulfur-bridged dimeric complex, [Pd(bipyridine)(SR)]2(ClO4)2(R=Me and Pr), and a free nitroxide radical.