Search

We have investigated the ligand effect on the gold-activated intramolecular amidiniumation of formamidine having a terminal alkyne, and observed the transformation of vinyl gold species into a gem-digold intermediate comprising two C–Au σ bonds, which represents a new binding mode for gem-digold species in the gold-promoted transformation of alkynes. [ABSTRACT FROM AUTHOR]

Single Co adatoms adsorbed on a double-layer NaCl film supported by Cu(111) were negatively charged after applying a positive voltage pulse to the sample in a scanning tunnelling microscope. Density functional calculations showed that the magnetic moment of Co changed from 3μB to 2.2μB after charge state manipulation. [ABSTRACT FROM AUTHOR]

Solvothermal reactions of Cd(OAc)2/Zn(OAc)2 with a new ligand, (pyridin-3-yl)methyl 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoate (L1), under different templates via an in situ ligand transformation reaction produced five coordination polymers, [CdL2(H2O)]n (1), [Cd1.5L3]n (2), [Cd2L4]n (3), [(ZnL2)·H2O]n (4) and {[Zn(1,3-BDC)(L1)]·MeCN·0.5H2O}n (5), where HL = 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid. Compound 1 is a three-dimensional (3D) wave-like structure constructed from 4-connected Cd(ii) nodes and L− linkers. Compounds 2 and 3 bear similar 2D networks built from metallocyclic [Cd4L4] units. Compound 4 features a wrinkled 2D layer based on metallocyclic [Zn4L4] units. Compound 5 has a novel 1D single-wall metal–organic nanotube (SWMONT) in which the 1,3-BDC ligands act as linkers to connect the [Zn2(L1)2] rings. The results reveal that the different templates have a significant effect on the final structures. Compounds 1–5 exhibited relatively high photocatalytic activity towards the degradation of methylene blue (MB) in aqueous solution under UV-Vis irradiation. The kinetics of the catalytic photodegradation reactions and the stabilities of photocatalysts were also investigated. [ABSTRACT FROM AUTHOR]

Novel Cr(iii) catalysts supported by PNPO phosphazane ligands of the type Ph2PN(R)P(Ph)OAr have been prepared, all of which, upon activation with MMAO-3A, are highly active in ethylene tri-/tetramerization with considerable selectivity. The effect of ligand substitution on the catalytic performance has been examined. The Cr precatalyst supported by the PNPO phosphazane ligand with an N-cyclohexyl achieved high activity of 316.7 kg (g Cr h−1)−1 and a high total selectivity of 85.1% towards valuable 1-hexene (45.7%) and 1-octene (39.4%) using chlorobenzene as the solvent at 35 bar and 40 °C. In methylcyclohexane, the precatalyst supported by [Ph2PN(iPr)P(Ph)OPh] exhibited a higher 1-octene selectivity (54.0%) with a considerable activity of 73.3 kg (g Cr h−1)−1 at 35 bar and 40 °C. With the fine-tuned ligand backbone, such a PNPO phosphazane-based catalyst system provides a mode for precise understanding of the impact of ligand variations on catalytic performance. [ABSTRACT FROM AUTHOR]

The first series of chiral phosphine-imidazole carbene ligands based on a 1,1′-binaphthyl framework were synthesized from (R)-2-amine-2′-(diphenylphosphino)-1,1′-binaphthyl (1) in a four-step pathway. After deprotonation of these phosphine-imidazolium salts with LiOtBu, and subsequent complexation with [Ir(COD)Cl]2 and anion exchange with NaBArF, phosphine-carbene chelated iridium complexes (R)-6a and (R)-6b were obtained. Their structures have been characterized by NMR and X-ray diffraction analysis. The NHC-phosphine rhodium complex (R)-6c has been also obtained by a similar synthetic method. These iridium complexes have been applied to catalyze the asymmetric hydrogenation of alkenes to give the corresponding products in moderate to excellent conversion (up to 99%) and moderate enantioselectivities under mild conditions (up to 61% ee). [ABSTRACT FROM AUTHOR]

The PdCl2-promoted reactions of methylenecyclopropanes (MCPs) 1bearing diaryl substituents on the terminal double bond were carefully investigated. The solvents employed significantly affected the reaction outcomes. It was found that dimeric allylpalladium(ii) complexes 2a–2fcan be obtained as the sole products in acceptable to good yields under mild reaction conditions with THF as the solvent, while dimeric allylpalladium(ii) complexes 2a–2falong with another type of dimeric allylpalladium(ii) complexes 4a–4ecan be obtained in good to high total yields if N,N-dimethylacetamide (DMAc) was used as the solvent. Moreover, using N,N-dimethylformamide (DMF) as the solvent in the presence of water, it was found that water can also participate in the reaction to form another type of dimeric allylpalladium(ii) complex 6as the minor product. All of these dimeric allylpalladium(ii) complexes reported in the paper have been characterized by X-ray crystal structure diffraction. [ABSTRACT FROM AUTHOR]