RESUMEN
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.
RESUMEN
An innovative tactic to prepare porous organic polymer membranes was developed via interfacial azo-coupling polymerization. The membranes possess plentiful anchoring sites for loading Pd nanoparticles, and served as a membrane reactor, which exhibits high-performance catalytic reduction with a flux of 27.3 t m-2 day-1 and good long-term stability due to almost zero Pd leaching.
RESUMEN
Hydrogenolysis of alkyl-substituted cyclopentadienyl (CpR ) ligated thorium tribenzyl complexes [(CpR )Th(p-CH2 -C6 H4 -Me)3 ] (1-6) afforded the first examples of molecular thorium trihydrido complexes [(CpR )Th(µ-H)3 ]n (CpR =C5 H2 (t Bu)3 or C5 H2 (SiMe3 )3 , n=5; C5 Me4 SiMe3 , n=6; C5 Me5 , n=7; C5 Me4 H, n=8; 7-10 and 12) and [(Cp# )12 Th13 H40 ] (Cp# =C5 H4 SiMe3 ; 13). The nuclearity of the metal hydride clusters depends on the steric profile of the cyclopentadienyl ligands. The hydrogenolysis intermediate, tetra-nuclear octahydrido thorium dibenzylidene complex [(Cpttt )Th(µ-H)2 ]4 (µ-p-CH-C6 H4 -Me)2 (Cpttt =C5 H2 (t Bu)3 ) (11) was also isolated. All of the complexes were characterized by NMR spectroscopy and single-crystal X-ray analysis. Hydride positions in [(CpMe4 )Th(µ-H)3 ]8 (CpMe4 =C5 Me4 H) were further precisely confirmed by single-crystal neutron diffraction. DFT calculations strengthen the experimental assignment of the hydride positions in the complexes 7 to 12.
RESUMEN
The monomeric actinide dihydrido complex [(CpAr*)(Cp*)ThH2(THF)] (2) bearing the super-bulky penta-arylcyclopentadienyl (CpAr* = C5Ar*5, Ar* = 3,5-tBu2-C6H3) and pentamethylcyclopentadienyl (Cp* = C5Me5) ligands was obtained for the first time. Complex 2 underwent unique Th-H addition reactions with various unsaturated compounds to afford the corresponding five-membered metallacycles, including the first example of actinide metallacyclopentyne [(CpAr*)(Cp*)Th(PhCH-C[triple bond, length as m-dash]C-CHPh)] (4).
RESUMEN
A series of mono-anionic non-carbocyclic ligands, including bidentate benzamidinate [PhC(NDipp)2] (Dipp = C6H3-2,6-iPr2), iminophosphinamide [Ph2P(NDipp)2] and phosphinoamide [Ph2PNDipp], and tridentate hydrotris(3,5-dimethyl-1-pyrazolyl)borate (TpMe2) were used to stabilize the corresponding thorium(iv) trialkyl complexes [PhC(NDipp)2]Th(CH2SiMe3)3 (1), [Ph2P(NDipp)2]Th(CH2SiMe3)3 (2), [Ph2P(NDipp)]Th(p-CH2-C6H4-Me)3 (3) and (TpMe2)Th(CH2SiMe3)3 (4), which were characterized by NMR spectroscopy and single-crystal X-ray analysis. Complexes 1-4 in combination with [Ph3C][B(C6F5)4] and AliBu3 form non-Cp-ligated actinide catalyst systems to show high activity and high cis-1,4-selectivity (89.9%) or trans-1,4-selectivity (91.4%) for the polymerization of isoprene. The reaction rate and selectivity of complexes 1 and 2 were controlled by the crowded space around the thorium centre, corroborated by the kinetics of the polymerization and the steric maps.
RESUMEN
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, 5â 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.
RESUMEN
A novel SPES-NH(2)-GA-Nafion® composite membrane with higher proton conductivity and lower methanol permeability was fabricated by covalent crosslinking layer-by-layer self-assembly of an unbalanced charged polyampholyte (SPES-NH(2)) and glutaraldehyde (GA) with controllable free sulfonic acid content.
