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Synthesis, Structure, and Reactivity of New Rhodium and Iridium Complexes, Bearing a Highly Electron-Donating PNP System. Iridium-Mediated Vinylic C−H Bond Activation

“…Interestingly, the dimeric byproduct Rh 2 Cl 2 (PNP) 3 , which was found in the analogous reaction of PNP(C 6 H 5 ),2a was not observed here. Its formation is prevented, most likely, by the bulky substituents on the phosphine ligand.…”

Intramolecular CH/OH Bond Cleavage with Water and Alcohol Using a Phosphine‐Free Ruthenium Carbene NCN Pincer Complex

“…The bond lengths of each pincer ligand arm of 8 resemble that of the monodearomatized portion of 6 . Double deprotonation of related Re,22 Rh,23 Pd/Pt,24 and Ni25 PNP pincer systems with a central 2,6‐dimethylpyridyl moiety have been described elsewhere; to our knowledge, this is the first reported pincer complex that contains two independently dearomatized pyridine rings.…”

The Methylene-Transfer Reaction: Synthetic and Mechanistic Aspects of a Unique C−C Coupling and C−C Bond Activation Sequence

“…C−C bond activation with the PCP-type complexes 1 , bearing phenyl groups on the diphosphine ligand, has been shown to take place upon heating to 100−110 °C. 2a,, Remarkably, direct insertion into a strong sp 2 −sp 3 C−C bond can take place even at room temperature when complex 1 is treated with an aryl iodide. High electron density together with coordinative unsaturation should favor C−C oxidative addition. 15a, In the system studied here, the phenyl phosphines impart a considerably lower electron density on the metal center in comparison to tert -butylphosphines in the PCP systems that have been shown to insert directly into strong C−C bonds at mild conditions. , Here, not only does the C−C cleavage process take place at room temperature but it is not the rate-determining step of the overall methylene-transfer reaction. Moreover, this is a unique example of a C−C cleavage process in which a metal inserts into a relatively sterically hindered C−C bond of a bulky benzyl group.…”