Rhodium Derivatives of Peroxoboronic Acids and Peroxoboric Acid: Formation of Metallatrioxaborolanes from an η²‐Peroxo Complex

Abstract

Heterocyclic peroxides with a five‐membered RhOOBO ring have been isolated by reaction of a rhodium peroxo complex with phenylboronic acids. They can be considered to be rhodium derivatives of perboric acid (see scheme) and phenylperboronic acids.

Rhodium‐Mediated Oxygenation of Nitriles with Dioxygen: Isolation of Rhodium Derivatives of Peroxyimidic Acids

“…The oxygen atom of the peroxyimidate ligand binds at the trans position to the isonitrile ligand, whereas the nitrogen atom coordinates in the trans position to the tetrafluoropyridyl ligand. The OO (1.4914(17) Å) and RhO (2.0473(13) Å) bond lengths of 5 a are comparable to the corresponding distances found for other rhodium dioxametallacycles such as trans ‐[Rh{κ 2 ‐ O OB(OH) O }(4‐C 5 NF 4 )(CN t Bu)(PEt 3 ) 2 ] (OO: 1.4974(14) Å; RhO 2.0366(10) Å)9c or trans ‐[Rh{κ 2 ‐ O OC(O) O }(4‐C 5 NF 4 )(CN t Bu)(PEt 3 ) 2 ] (OO: 1.469(4) Å; RhO 2.040(3) Å) 2c. The O‐O‐Rh angle of trans ‐[Rh{κ 2 ‐ O OB(OH) O }(4‐C 5 NF 4 )(CN t Bu)(PEt 3 ) 2 ] (108.29(7)°) and trans ‐[Rh{κ 2 ‐ O OC(O) O }(4‐C 5 NF 4 )(CN t Bu)(PEt 3 ) 2 ] (107.7(2)°) are slightly smaller than that in 5 a (109.61(9)°).…”

“…The shifts are rather small to be associated with isolated OO modes 2c. The data are in accordance with the absorption bands for the rhodium peroxycarbonato complex trans ‐[Rh{κ 2 ‐ O OC(O) O }(4‐C 5 NF 4 )(CN t Bu)(PEt 3 ) 2 ] (Rh{κ 2 ‐ O OC(O) O }: 969 cm −1 ; Rh{κ 2 ‐ 18 O 18 OC(O) O }: 948 cm −1 );2c they differ from the data for the rhodium metallacycle trans ‐[Rh{κ 2 ‐ O OB(OH) O }(4‐C 5 NF 4 )(CN t Bu)(PEt 3 ) 2 ] (OO: 654 cm −1 ; 18 O 18 O: 644 cm −1 ) 9c…”

Rhodium and Iridium Fluorido and Bifluorido Complexes Derived from Peroxido Precursors

“…This indicates a hindered rotation of the tetrafluoropyridyl ligand about the Rh–C bond. [16c], A broad signal at δ = –179.2 ppm was split into a doublet with 1 J F,H = 402 Hz when the spectrum was recorded at –40 °C (see Figure , a). In the 19 F{ 1 H} NMR spectrum this resonance appears as a singlet and can be assigned to the distal fluorine atom of the bifluorido ligand (see Figure , b).…”

“…Presumably, through‐space fluorine–fluorine coupling is responsible for the large coupling constant of J F,F = 70 Hz. [17b], The corresponding signal appears as a doublet of doublet of triplets at δ = –349.0 ppm. It is assigned to the metal‐bound fluorine atom in the cis position to the tetrafluoropyridyl ligand.…”

Dioxygen Reactivity with a Ferrocene–Lewis Acid Pairing: Reduction to a Boron Peroxide in the Presence of Tris(pentafluorophenyl)borane

“…For a BOOC motif resulted from a phosphine–borane reaction with singlet O 2 , the structural parameters are 1.454(6) and 1.473(4) Å, respectively 8a. A BOORh moiety resulted from the reaction of a Rh‐peroxo with a boronic acid displays a trigonal boron,8c with the BO distance shorter (1.400(2) Å) and the OO distance longer (1.497(1) Å) than the above, likely because of the stronger interaction between O and three‐coordinate boron. The B‐O‐O angle (106.9(1)°) is similar to the C‐O‐O angle (107.5(2)°) in bis(triphenylmethyl)peroxide 11…”