Diphosphines with natural bite angles near 120.degree. increase selectivity for n-aldehyde formation in rhodium-catalyzed hydroformylation. [Erratum to document cited in CA117(3):25899x]

Silsesquioxane dendrimers as catalysts: A bite-sized molecular dynamics study

“…Two atom types were added to represent the tetrahedral phosphorus species found in complexes and for the metal centre itself. Parameters were adapted from Casey et al, [19][20][21] Gleich et al 24,25 and from existing parameters within MM+ to work with the new atom types. Test structures were modeled using the protocol below until agreement was reached with the structures obtained by Angermund et al 17 A successful set of parameters was defined as those that could reproduce the same trends in this series of ligands and were within ± 4 • of the X-ray values.…”

“…14 Solid Angles, 15 Pocket Angles, 16 the Accessible Molecular Surface Model, 17 the Ligand Repulsive Energy 18 and the Bite Angle. [19][20][21] The bite angle of a ligand is defined as the preferred chelation of a bidentate ligand such as a diphosphine. Dendrimers are very complex molecules, with many degrees of freedom.…”

Highly (regio)selective hydroformylation of olefins using self-assembling phosphines

“…As such, phosphine ligands have become a powerful and flexible factor to influence the activity, chemo-and regioselectivity of rhodium catalysts. [16][17][18] Indeed, denticity, 19,20 electronic 21 and steric properties 22,23 have been showed to have direct impact on the performance of the catalyst. While catalyst activity and reaction yield matter, an essential aspect of hydroformylation resides in regioselectivity of the reaction.…”

Integration of Milstein Ru–PNN and Rh–Tribi/Tetrabi for Isomerization Linear Selective Hydroformylation of Far Internal Alkenes

“…Directed by our efforts in looking for another type of robust dual-catalysis system, in this paper, we reported a Milstein Ru–PNN catalyst integrated with our Rh–Tribi/Tetrabi catalysts for isomerization linear hydroformylation of 2-alkenes up to 4-alkenes, giving greatly improved linear selectivities and activities (linear selectivity improvements of 2.2–58%, up to 94.2–98.6%, and turnover number improvements of 61–335 TON, up to 385–851, Figure c) compared to the Ru–PNN/Rh–Bisbi system. Such multidentate phosphorus ligands based on tetra- and triphosphine motifs can enhance the local phosphorus donor concentration and steric bulkiness around the Rh metal center, and thus, improved regioselectivities and activities (linear selectivity up to 99%, TOF up to 10 000 h –1 ) were achieved for terminal alkenes. ,, Also, well-known diphosphine ligand Bisbi − was examined as a reference, and a novel dual-metal isomerization linear hydroformylation mechanism was proposed.…”