Singly hydrogen bonded supramolecular ligands for highly selective rhodium-catalyzed hydrogenation reactions

H bonds make the catalysts! A single hydrogen bond between ligands coordinated to a rhodium center is critical for the formation of pure supramolecular catalysts for asymmetric hydrogenation reactions. The ester group of the amidite ligand (see scheme) also forms a hydrogen bond with the coordinated substrate. Use of the heterocomplex afforded the highest enantioselectivity reported to date for the hydrogenation of several ester substrates

Iminobisphosphines to (Non-)Symmetrical Diphosphinoamine Ligands: Metal-Induced Synthesis of Diphosphorus Nickel Complexes and Application in Ethylene Oligomerisation Reactions

We describe the synthesis of a range of novel iminobisphosphine ligands based on a sulfonamido moiety [(R1SON)-N-2=P(R-2)(2)-P(R-3)(2)]. These molecules rearrange in the presence of nickel by metal-induced breakage of the P-P bond to yield symmetrical and nonsymmetrical diphosphinoamine nickel complexes of general formula Ni{[P(R-2)(2)]N(SO2R1)P(R-3)(2)}Br-2. The complexes can be isolated and are very stable. Upon activation by MAO, these complexes oligomerise ethylene to small chain oligomers (mainly C-4-C-8) with high productivity. Surprisingly fast codimerisation reactions of ethylene with butenes is observed, leading to a high content of branched C-6 products

Self-Assembled Organometallic Nickel Complexes as Catalysts for Selective Dimerization of Ethylene into 1-Butene

Sulfonamido-phosphorus and aminophosphine ligands self-assemble to readily form active and stable nickel catalysts that are highly selective for the dimerization of ethylene to 1-butene. The self-assembled allyl-nickel complexes are zwitterionic and are stabilized by hydrogen bond interactions between the two ligands. These organometallic cis-diphosphine complexes rearrange under an ethylene atmosphere to give trans-diphosphine catalysts, with one monoanionic P,O METAMORPhos ligand and an aminophosphine