Tuning Ruthenium Carbene Complexes for Selective P-H Activation through Metal-Ligand Cooperation.

The use of iminophosphoryl-tethered ruthenium carbene complexes to activate secondary phosphine P-H bonds is reported. Complexes of type [(p-cymene)-RuC(SO Ph)(PPh NR)] (with R = SiMe or 4-C H -NO ) were found to exhibit different reactivities depending on the electronics of the applied phosphine and the substituent at the iminophosphoryl moiety. Hence, the electron-rich silyl-substituted complex undergoes cyclometallation or shift of the imine moiety after cooperative activation of the P-H bond across the M=C linkage, depending on the electronics of the applied phosphine.

A diamino-substituted carbodiphosphorane as strong C-donor and weak N-donor: isolation of monomeric trigonal-planar L·ZnCl.

The isolation, structural characterization and coordination chemistry of a di(amino)-substituted carbodiphosphorane (CDP) are reported. Compared to the analogue, dianionic bis(iminophosphoryl)methandiides, the CDP is a stronger C-, but much weaker N-donor which led to the isolation of solely C-coordinated metal complexes amongst an unusual monomeric trigonal-planar L·ZnCl complex.

Unraveling the High Activity of Ylide-Functionalized Phosphines in Palladium-Catalyzed Amination Reactions: A Comparative Study with JohnPhos and PBu.

Comprehensive mechanistic insights into the activity of different catalysts based on different ligands are important for further ligand design and catalyst improvement. Herein, we report a combined computational and experimental study on the mechanism and catalytic activity of the ylide-substituted phosphine CyP-C(Me)PCy (keYPhos, ) in C-N coupling reactions including a comparison with the established and often-applied phosphines JohnPhos () and P(Bu) (). Density functional theory (DFT) calculations together with the possible isolation of several intermediates within the catalytic cycle demonstrate that readily forms low-coordinated palladium complexes [such as ], which easily undergo oxidative addition and subsequent amine coordination as well as reductive elimination.

Isolation of a Diylide-Stabilized Stannylene and Germylene: Enhanced Donor Strength through Coplanar Lone Pair Alignment.

The preparation of the first stable diylide-substituted stannylene and germylene (Y E, with E=Ge, Sn and Y=[PPh -C-SO Tol] ) is reported. The synthesis is easily accomplished in one step from the sulfonyl-substituted metalated ylide YNa and the corresponding ECl precursors. Y Ge and Y Sn exhibit unusual structures in the solid state and in solution, in which the three adjacent lone pairs in the C-E-C linkage are arranged coplanar to each other.

Isolation of the Metalated Ylides [Ph P-C-CN]M (M=Li, Na, K): Influence of the Metal Ion on the Structure and Bonding Situation.

The isolation and structural characterization of the cyanido-substituted metalated ylides [Ph P-C-CN]M (1-M; M=Li, Na, K) are reported with lithium, sodium, and potassium as metal cations. In the solid-state, most different aggregates could be determined depending on the metal and additional Lewis bases. The crown-ether complexes of sodium (1-Na) and potassium (1-K) exhibited different structures, with sodium preferring coordination to the nitrogen end, whereas potassium binds in an unusual η -coordination mode to the two central carbon atoms.

A Highly Active Ylide-Functionalized Phosphine for Palladium-Catalyzed Aminations of Aryl Chlorides.

Ylide-functionalized phosphine ligands (YPhos) were rationally designed to fit the requirements of Buchwald-Hartwig aminations at room temperature. This ligand class combines a strong electron-donating ability comparable to NHC ligands with high steric demand similar to biaryl phosphines. The active Pd species are stabilized by agostic C-H⋅⋅⋅Pd rather than by Pd-arene interactions.

Ylide-Functionalized Phosphines: Strong Donor Ligands for Homogeneous Catalysis.

Phosphines are important ligands in homogenous catalysis and have been crucial for many advances, such as in cross-coupling, hydrofunctionalization, or hydrogenation reactions. Herein we report the synthesis and application of a novel class of phosphines bearing ylide substituents. These phosphines are easily accessible via different synthetic routes from commercially available starting materials.

Versatile Modes of Cooperative B-H Bond Activation Reactions in Ruthenium-Carbene Complexes: Addition, Ring-Opening and Insertion.

Cooperative B-H bond activation reactions with thio- and iminophosphoryl tethered ruthenium-carbene complexes are reported. The complexes show surprisingly different reactivities towards the commonly employed boranes CatBH, PinBH and BH ⋅LB as a result of different modes of metal-ligand cooperation. Although the iminophosphoryl system allows for selective 1,2-addition of the B-H bond across the Ru=C double bond, the sulfur analogue only delivers the 1,2-addition product for CatBH, whereas activation of BH and PinBH lead to further insertion reactions in one or more sides of the Ru-C-P-S-ring.

Metalated Ylides: A New Class of Strong Donor Ligands with Unique Electronic Properties.

The development and design of new ligand systems with special donor properties has been essential for crucial advances made in main-group-element and transition-metal chemistry over the years. This Forum Article focuses on metalated ylides as novel ligand systems. These anionic congeners of bisylides possess likewise two lone pairs of electrons at the central carbon atom and can thus function as X,L-type ligands with strong donor abilities.

The Bonding Situation in Metalated Ylides.

Quantum chemical calculations have been carried out to study the electronic structure of metalated ylides particularly in comparison to their neutral analogues, the bisylides. A series of compounds of the general composition Ph P-C-L with L being either a neutral or an anionic ligand were analyzed and the impact of the nature of the substituent L and the total charge on the electronics and bonding situation was studied. The charge at the carbon atom as well as the dissociation energies, bond lengths, and Wiberg bond indices strongly depend on the nature of L.