[(^tBu₂PCH₂SiMe₂)₂N]Rh^I? Rapidly Reversible H−C(sp³) and H−C(sp²) Bond Cleavage by Rhodium(I)

Abstract

The product of the reaction of (tBu2PCH2SiMe2)2N− (MgCl+ salt) with [RhCl(cyclooctene)2]2 is a RhIII complex where one tBu methyl C−H bond has oxidatively added to Rh: (PNP*)RhH. This is in rapid exchange among all 9 × 4 C−H bonds of the four tBu groups. (PNP*)RhH undergoes oxidative addition equilibrium with the C−H bonds of benzene at ∼103 s−1 at 25 °C and oxidatively adds the ring C−H of other arenes. (PNP*)RhH forms η2-olefin complexes with several olefins and dehydrogenates allylic C−H bonds to form (PNP)Rh(H)2.

Spin State, Structure, and Reactivity of Terminal Oxo and Dioxygen Complexes of the (PNP)Rh Moiety

“…Indeed, molecular oxygen appears to lack pure s-donor power, in the absence of electron transfer to O 2 , by virtue of not complexing to any non-redox active Lewis acid, for ex- [3] is converted cleanly and completely by O 2 to form H NMR spectra consistent with a C 2v structure (A), although structure B (C s symmetry) might be fluxional, and thus show time-averaged C 2v symmetry.…”

“…We have shown that [3] three-coordinate [RhA C H T U N G T R E N N U N G (PNP)] has a ground-state structure with one tBu methyl group oxidatively added to Rh I , to yield the structure [Rh III H{tBu 2 PCH 2 SiMe 2 NSiMe 2 CH 2 P-…”

Structure and Reactivity of Dinitrogen Rhodium Complexes Containing N‐Heterocyclic Carbene Ligands

“…[32][33][34] One other example of a low-valent rhodium complex of molecular nitrogen was reported by Caulton's group featuring a unique PNP ligand, [(tBu 2 PCH 2 SiMe 2 ) 2 N]Rh(N 2 ), which has a very low ν(N-N) of 2068 cm -1 . [35] Interestingly, the three-coordinate fragment of Caulton's complex [36] and the similar (PCP)-Rh complex, [Me 2 C 6 H(CH 2 PtBu 2 ) 2 ]Rh, reported by Milstein [37] coordinate oxygen to give Rh I -O 2 complexes similar to 1a and 1b with O-O bond lengths of 1.363 and 1.365 Å, respectively.…”

[IrCl{N(CHCHPtBu2)2}]−: a versatile source of the IrI(PNP) pincer platform

“…Typical pathways for the generation of these reactive intermediates comprise the thermal or photochemical dissociation of small molecules, such as N 2 , CO, and olefins, 9 or the reductive elimination of hydrocarbons from M III hydride hydrocarbyl intermediates, e.g. intramolecularly within a cyclometalated complex 10,11 or by reaction of a dihydrido complex with an alkene as a H 2 acceptor. 12,13 Recently, we reported the synthesis of the iridium(II) complex [IrCl(L6 tBu )] (1, L6 tBu = N(CHCHPtBu 2 ) 2 Scheme 1) by the oxidation of [IrCl(H)R(HL4 tBu )] (R = 1-cyclooctenyl) with benzoquinone as a hydrogen acceptor.…”