1428140-16-2Relevant academic research and scientific papers
Ligand effects on the hydrogenation of biomass-inspired substrates with bifunctional Ru, Ir, and Rh complexes
Jansen, Eveline,Jongbloed, Linda S.,Tromp, Dorette S.,Lutz, Martin,De Bruin, Bas,Elsevier, Cornelis J.
, p. 1737 - 1744 (2013)
We herein report on the application and structural investigation of a new set of complexes that contain bidentate N-heterocyclic carbenes (NHCs) and primary amine moieties of the type [M(arene)Cl(L)] [M=Ru, Ir, or Rh; arene=p-cymene or pentamethylcyclopentadienyl; L=1-(2-aminophenyl)-3-(n-alkyl) imidazol-2-ylidine]. These complexes were tested and compared in the hydrogenation of acetophenone with hydrogen. Structural variations in the chelate ring size of the heteroditopic ligand revealed that smaller chelate ring sizes in combination with ring conjugation in the ligand are beneficial for the activity of this type of catalyst, favoring an inner-sphere coordination pathway. Additionally, increasing the steric bulk of the alkyl substituent on the NHC aided the reaction, showing almost no induction period and formation of a more active catalyst for the n-butyl complex relative to complexes with smaller Me and Et substituents. As is common in hydrogenation reactions, the activity of the complexes decreases in the order Ru>Ir>Rh. The application of [Ru(p-cym)Cl(L)]PF6, which outperforms its reported analogues, has been successfully extended to the hydrogenation of more challenging biomass-inspired substrates. Adding value to biomass: The influence of structural variations of N-heterocyclic carbene-amine motif in half-sandwich Ru, Ir, and Rh complexes on the hydrogenation of biomass-inspired substrates is reported. Through this study insight is gained for the future rational design of hydrogenation catalysts for the conversion of biomass into useful/added-value compounds. Copyright
Hg(II), Ag(I) and Au(I) complexes with aniline or pyridine-functionalized N-heterocyclic carbene
Zhuang, Ren-Tai,Lin, Wan-Jung,Zhuang, Rui Rui,Hwang, Wen-Shu
, p. 132 - 141 (2013/04/10)
[Hg(La)2](PF6)2 (1), [Hg(L b)2](PF6)2 (2), [Hg(L c)2](PF6)2 (3), [Ag(L a)2]I (4) and Au(La)Cl (5) (La, Lb, and Lc are aniline or pyridine N-functionalized imidazol-2-ylidene) have been synthesized and characterized. Single crystals of 1·MeOH, 3 and 5 are obtained and their crystal structures are determined by X-ray diffraction analysis. The molecular structure of 1·MeOH shows that Hg(II) center is coordinated to two carbene ligands, one nitrogen atom from aniline group and one oxygen atom from methanol. The anions are embedded between two cations layers and linked the cations through the intermolecular hydrogen bonding. The Hg(II) center of 3 is coordinated to two carbene ligands and two nitrogen atoms from pyridine group. The PF6- anions of 3 hold two adjacent cations through Hg?F interactions and H?F hydrogen bonding and the crystal packing consists of alternating anion and cation layers. The Au atom of 5 is linearly coordinated with a carbenoic carbon and a chloro ligand, and the molecules are neatly arranged to a one-dimensional hole through weak hydrogen bonding interactions. For 1·MeOH and 5, the -NH2 group of aniline plays an important role in stabilizing the crystal structure through intramolecular and intermolecular hydrogen bonding interactions.
