Isospecific polymerization of propene by new indolyl-pyridylamido Zr(IV) catalysts
摘要:
New zirconium complexes bearing indolyl-pyridylamido ligands [-NNN-] have been synthesized and used as catalysts in ethylene and propene polymerization in the presence of (AlBu2H)-Bu-1/MAO as cocatalytic system. Complexes 1 and 2, bearing ligands with a different steric hindrance on the carbon bridging the pyridine and the aniline moieties, exhibited remarkable catalytic activity for ethylene and propene polymerization, affording ultrahigh molecular weight polymers with monomodal molecular weight distributions. Moreover, the presence of the 2-isopropyl phenyl substituent on the bridging carbon (complex 2) resulted in higher stereoselectivity and regioselectivity providing a polypropylene sample with an [mmmm] content up to 96% and 1.3% of regioinversion. On the other hand, the change of the substituents of the aniline moiety (complex 3) gave a zirconium complex which resulted completely inactive both in the ethylene and propene polymerization. (c) 2013 Elsevier B.V. All rights reserved.
Iron-Catalyzed Hydroboration: Unlocking Reactivity through Ligand Modulation
作者:Maialen Espinal-Viguri、Callum R. Woof、Ruth L. Webster
DOI:10.1002/chem.201602818
日期:2016.8.8
hydroboration (HB) of alkenes and alkynes is reported. A simple change in ligand structure leads to an extensive change in catalyst activity. Reactions proceed efficiently over a wide range of challenging substrates including activated, unactivated and sterically encumbered motifs. Conditions are mild and do not require the use of reducing agents or other additives. Large excesses of borating reagent are not required
Tunablearylalkylionicliquids (TAAILs) are a promising class of imidazolium- or triazolium-based ionicliquids. Contrary to “standard” all-alkyl ionicliquids, these carry an aryl ring together with a linear or branched alkyl chain. Their application in the cobalt-catalyzed hydroarylation/hydroamination of alkenes and anilines is presented. The catalytic system is tolerant toward air and is scalable