Dimetallic Dioxygen Activation Leading to a Doubly Oxygen‐Bridged Dirhodium Complex

Abstract

Die einfache Spaltung von Disauerstoff und seine selektive Insertion in Rh‐Alken‐Bindungen beobachtet man in Gegenwart von [{Rh(PhN3Ph)(C8H12)}n] (n=1 und 2). Die Struktur des gebildeten Dirhodadioxetankomplexes (siehe Bild) und kinetische Messungen stützen einen Dimetallmechanismus für diesen Prozess, der mit 100 % Atomökonomie abläuft.

From Olefins to Ketones via a 2‐Rhodaoxetane Complex

“…We previously observed [6] that 1 is kinetically unstable and forms [{Rh(PhN 3 Ph)(HOC 8 H 11 )} n ] (6) on heating in [D 6 ]benzene at 65 8C. Accordingly, complex 5 results quantitatively from the reaction of 6 with PMe 3 , as observed in a separate experiment.…”

“…We have previously described [6] 2). This result provides new insight into the oxygenation of olefins with dioxygen, because it shows for the first time formation of a ketone from an isolated 2-rhoda-(III)oxetane complex resulting from an internal olefin.…”

Stereospecific Carbene Polymerization with Oxygenated Rh(diene) Species

“…Previously reported [(C 8 H 12 O)Rh(N 3 -ligand)] + species [11] turned out to be nonreactive towards EDA, which can be expected for these saturated 18-valence-electron Rh III species. [13] Complexes 4-6 were evaluated as catalyst precursors in the carbene polymerization of EDA ( Table 1). The triazenide complexes 5 and 6 (Scheme 4) [13] seemed good candidates to test our hypothesis that active allylic [(C 8 H 11 )Rh III -OH] + species can be generated from Complex 5 is formed in good yield and in good purity by oxidation of the triazenide precursor [(C 8 H 12 )Rh(N 3 Ph 2 )] (4) with O 2 .…”

“…[11,13] More importantly, b-hydroxy elimination from the cationic allyl-b-alkyl-hydroxide rhodium(III) species is exergonic by approximately 5 kcal mol À1 and has an accessible transition state barrier of 28 kcal mol À1 . This transformation is experimentally observed in the rearrangement from 5 to 6 and in related reported reactions.…”

From Olefins to Ketones via a 2‐Rhodaoxetane Complex

“…We have previously described [6] facile oxygenation of [Rh(PhN 3 Ph)(C 8 H 12 )] (C 8 H 12 = 1,5-cyclooctadiene = cod, PhN 3 Ph = 1,3-diphenyltriazenide) with dioxygen to give dinuclear 2-rhoda(III)oxetane complex [{Rh(PhN 3 Ph)-(OC 8 H 12 )} 2 ] (1, Scheme 2), in which both oxygen atoms from dioxygen were incorporated with 100 % atom efficiency. On treating a suspension of 1 with trimethylphosphane in [D 6 ]benzene at 35 8C, quantitative elimination of the organic fragment as 4-cyclooctenone (2) and formation of pentacoordinate Rh I complex [Rh(PhN 3 Ph)(PMe 3 ) 3 ] (3) was observed (Scheme 2).…”