A mononuclear divalent ytterbium hydrido complex supported by a super-bulky scorpionate ligand.

The first mononuclear divalent ytterbium hydride complex [(TpAd,iPr)Yb(H)(THF)] (TpAd,iPr = hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate) (2) bearing a terminal hydrido ligand was obtained by hydrogenolysis of the benzyl precursor in hexane. Complex 2 exhibited two different reaction patterns towards allenes: Yb-H addition with cyclohexylallene and deprotonation of 1,1-dimethylallene.

Scandium and lanthanum hydride complexes stabilized by super-bulky penta-arylcyclopentadienyl ligands.

Hydrogenolysis of the half-sandwich penta-arylcycopentadienyl-supported rare-earth metal dibenzyl complexes [(CpAr5)Ln(p-CH2-C6H4-Me)2(THF)] (CpAr5 = C5Ar5, Ar = 3,5-iPr2-C6H3; Ln = Sc, La) afforded a bimetallic scandium complex [(CpAr5)Sc(H)(µ-OC4H9)]2 (2) with two terminal hydrido ligands, and a double-sandwich bimetallic lanthanum hydride complex [(CpAr5)La(µ-H)]2 (4) bearing the reduced CpAr5 ligand. DFT calculations were conducted to elucidate the reaction profiles.

Mononuclear calcium complex as effective catalyst for alkenes hydrogenation.

Hydrogenolysis of the scorpionate-supported calcium benzyl complex [(TpAd,iPr)Ca(p-CH2C6H4-Me)(THP)] (TpAd,iPr = hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate, THP = tetrahydropyran) (2-THP) afforded the mononuclear calcium hydrido complex [(TpAd,iPr)Ca(H)(THP)] (3). Under mild conditions (40 °C, 10 atm H2, 5 mol% cat.), complex 3 effectively catalyzed the hydrogenation of a variety of alkenes, including activated alkenes, semi-activated alkenes, non-activated terminal and internal alkenes. Mononuclear calcium unsubstituted alkyl complex [(TpAd,iPr)Ca{(CH2)4Ph}(THP)] (6), proposed as the catalytic hydrogenation intermediate, was isolated and structurally characterized.

Super-Bulky Penta-arylcyclopentadienyl Ligands: Isolation of the Full Range of Half-Sandwich Heavy Alkaline-Earth Metal Hydrides.

Hydrogenolysis of the half-sandwich penta-arylcyclopentadienyl-supported heavy alkaline-earth-metal alkyl complexes (CpAr )Ae[CH(SiMe3 )2 ](S) (CpAr =C5 Ar5 , Ar=3,5-i Pr2 -C6 H3; S=THF or DABCO) in hexane afforded the calcium, strontium, and barium metal-hydride complexes as the same dimers [(CpAr )Ae(µ-H)(S)]2 (Ae=Ca, S=THF, 2-Ca; Ae=Sr, Ba, S=DABCO, 4-Ae), which were characterized by NMR spectroscopy and single-crystal X-ray analysis. 2-Ca, 4-Sr, and 4-Ba catalyzed alkene hydrogenation under mild conditions (30 °C, 6 atm, 5 mol % cat.), with the activity increasing with the metal size. A variety of activated alkenes including tri- and tetra-substituted olefins, semi-activated alkene (Me3 SiCH=CH2 ), and unactivated terminal alkene (1-hexene) were evaluated.

Hydrothermal derived nitrogen doped SrTiO3 for efficient visible light driven photocatalytic reduction of chromium(VI).

In this work, we report on the synthesis of nitrogen doped SrTiO3 nanoparticles with efficient visible light driven photocatalytic activity toward Cr(VI) by the solvothermal method. The samples are carefully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy and photocatalytic test. It is found that nitrogen doping in SrTiO3 lattice led to an apparent lattice expansion, particle size reduction as well as subsequent increase of Brunner-Emmet-Teller surface area. The visible light absorption edge and intensity can be modulated by nitrogen doping content, which absorption edge extends to about 600 nm. Moreover, nitrogen doping can not only modulate the visible light absorption feature, but also have consequence on the enhancement of charge separation efficiency, which can promote the photocatalytic activity. With well controlled particle size, Brunner-Emmet-Teller surface area, and electronic structure via nitrogen doping, the photocatalytic performance toward Cr(VI) reduction of nitrogen doped SrTiO3 was optimized at initial hexamethylenetetramine content of 2.