Reactivity of rhodium and iridium peroxido complexes towards hydrogen in the presence of B(C₆F₅)₃ or [H(OEt₂)₂][B{3,5-(CF₃)₂C₆H₃}₄]

Abstract

Rh and Ir peroxido complexes have been studied in the metal-mediated hydrogenation of O2. Dissimilar reaction pathways have been found on using the Lewis-acid B(C6F5)3 or the Brønsted-acid [H(OEt2)2][B{3,5-(CF3)2C6H3}4] to give H2O·B(C6F5)3 or H2O2.

Direct Synthesis of Hydrogen Peroxide in Water by Means of a Rh-Based Catalyst

“…While the catalytic reaction with 1 was carried out in water, the reaction intermediates 2 – 4 were isolated in organic solvents such as acetonitrile (CH 3 CN) and dimethyl sulfoxide (DMSO). This is a new approach to the homogeneous direct synthesis of H 2 O 2 (Table S1 in the Supporting Information for figure numbers, and Figures – and Figures S1–S11 in the Supporting Information for characterization of the Rh complexes).…”

Doping-induced decomposition of organic semiconductors: a caveat to the use of Lewis acid p-dopants

“…53,55 Then, as reaction proceeds, these two broad peaks seem to shift, widen and broaden further, eventually colliding as a very broad signal (9-2 ppm). On the other hand, right after B(C 6 F 5 ) 3 addition, the B(C 6 F 5 ) 3 -OH 2 signal at 4.7 ppm 39,48,49 appeared suppressed and shifted. Only as reaction proceeded, it gradually appeared as a strong broad peak at 4.7 ppm.…”

“…For both material combinations 1 H-NMR provides evidence for the formation of a B(C 6 F 5 ) 3 -OH 2 complex with the characteristic peak at 4.7 ppm. 39,48,49 For the PTAA:B(C 6 F 5 ) 3 27 mol% system, it is obvious that the addition of B(C 6 F 5 ) 3 in the solution results in a gradual transformation of PTAA. The gradual shielding/broadening of the aromatic protons (very broad peak 8.5-1.5 ppm, broad peak at 4.68 ppm) indicates a possible quinoid ring formation (vide infra).…”

Rhodium Disulfur and Dioxygen Complexes: Examination of Boron Secondary Coordination Sphere Effects

“…By 11 B NMR spectroscopy, two signals at dB ≈ 52 ppm and 31 ppm, assigned to R2BOR e.g., Cy2BOBCy2 and RB(OR)2 e.g., (CyOB)3, respectively were observedthese decomposition products are similar to those described by Braun and co-workers for treatment of an {[Ir]-O2} complex with BCy2Cl (vide supra). 9 These data suggest formation of a series of isomeric C1symmetric [Rh III (diphosphine)2] + compounds, some likely with O2 bound, that result from decomposition of the projecting pendant boranes. For reference, it is well-accepted that trialkylboranes undergo autooxidation…”

“…8 In a related transformation, the iridium(III) congener, trans-[Ir(4-C5F4N)(CN t Bu)(P i Pr3)2(h 2 -O2)] was shown to undergo reaction with ClBCy2 to give trans-[Ir(4-C5F4N)(CN t Bu)(P i Pr3)2(Cl)2] in addition to Cy2BOBCy2 and (CyBO)3, likely through the intermediacy of Cy2BO-OBCy2, sourced from a structurally similar k 1 -OOBCy2 peroxy compound, trans-[Ir(4-C5F4N)(CN t Bu)(P i Pr3)2(k 1 -OOBCy2)(Cl)] (Figure 1B). 9 In the context of sulfur chemistry, [Ir(dppe)2(h 2 -S2)] + was observed to undergo methylation using methyl fluorosulfonate (CH3SO3F) to give [Ir(dppe)2(h 2 -(SCH3S)] + , 10 whereas [Rh III (k 2 -dppe)(k 1 -dppe)(h 2 -S2)(H)] was found to promote thiirane formation using substituted norbornenes 11 (Figure 1A). In a recent contribution, we reported on the synthesis of a rhodium(I) bis(diphosphine) compound, [Rh I (P2B Cy 4)2]BPh4 (1) (P2B Cy 4 = 1,2-bis(di(3-dicyclohexylboraneyl)propylphosphino)ethane) that was found to be reactive toward nucleophiles (hydride and alkyl anions), undergoing functionalization at its boron-rich SCS and not at rhodium.…”