Versatile Access to Very Short P═P Double Bonds in Mixed-Valent 1λ⁵-Diphosphenes via 1,3-Silyl Migration

Abstract

The metathesis reaction of LiP(SiR 3 )Ar* (R = iPr and Ph; Ar* = Mes and Tipp) with Ph 2 POCl yields Ar*(R 3 Si)P−P(O)Ph 2 . These diphosphane monoxides can be observed by NMR spectroscopy. However, they are intrinsically instable, and 1,3-trihydrylsilyl migration leads to the formation of 1λ 5 -diphosphenes of the type Ar*PP(OSiR 3 )Ph 2 with very large characteristic 1 J(P,P) coupling constants. A very short PP bond has been observed for the 1λ 5 -diphosphene TippPP(OSiPh 3 )Ph 2 . These 1λ 5 -diphosphenes are only stable in the crystalline state but degrade in solution to Ph 2 P−O−SiR 3 via elimination of the Ar*P: phosphinidenes which form secondary degradation products such as triaryl-cyclotriphosphanes. Formation of the 1λ 5 -diphosphene TippPP(OSiPh 3 )Ph 2 via 1,3-trihydrylsilyl migration from P to O and the fate due to PP bond cleavage has been verified by theoretical studies.

Formation, Reactivity and Decomposition of Aryl Phospha-Enolates

“…Whilst 6 has been reported as a reaction intermediate, [16] to the best of our knowledge it has not yet been structurally authenticated or isolated. The unexpected formation of this compound through carbon monoxide extrusion from an acyl-phosphine to our knowledge only has one literature precedent: on warming from -90 °C to room temperature, t BuP(H)C(O)(Cl) extrudes CO to form t BuP(H)(Cl).…”

Formation, Reactivity and Decomposition of Aryl Phospha‐Enolates

“…Whilst 6 has been reported as a reaction intermediate, [17] to the best of our knowledge it has not yet been structurally authenticated or isolated. The unexpected formation of this compound through carbon monoxide extrusion from an acyl‐phosphine to our knowledge only has one literature precedent: on warming from −90 °C to room temperature, t BuP(H)C(O)(Cl) extrudes CO to form t BuP(H)(Cl) [18] .…”

Cross-Coupling of CO and an Isocyanide Mediated by a Tetrameric Magnesium Hydride Cluster

“…48 Related species have recently been documented from Kretschmer's group. 49 Previously we showed that 1a reacts with two equiv. CO by a deoxygenative pathway leading to the formation of a coordinated acetaldehyde enolate.…”