Reactions of an Osmium Bis(dihydrogen) Complex under Ethylene: Phosphine Addition to a C–C Double Bond and C–H Bond Activation of Fluoroarenes

Bajo, Sonia; Esteruelas, Miguel A.; López, Ana María; Oñate, Enrique

doi:10.1021/om2005854

Cited by 22 publications

(12 citation statements)

References 72 publications

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“…The reactivity of 1 toward fluorobenzene and 1,3-difluorobenzene agrees well with that recently reported by Braun for RhH(PEt 3 ) 3 , containing monodentated phosphines instead of a POP pincer. However, it is in contrast with the behavior observed for the saturated compounds OsTp{κ 1 - C [NC 5 H 3 Me]}(η 2 -CH 2 CH 2 ) 2 and [OsTp(CH 2 CH 2 P i Pr 3 )(η 2 -CH 2 CH 2 ) 2 ]BF 4 (Tp = hydridotris(pyrazolyl)borate), which activate fluorobenzene, 1,3-difluorobenzene, and substituted 1,3-chlorobenzenes, via σ-bond metathesis, to afford products resulting from the cleavage of the C–H bond more distant from the substituents.…”

Section: Resultsmentioning

confidence: 69%

POP–Rhodium-Promoted C–H and B–H Bond Activation and C–B Bond Formation

2015

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The square-planar monohydride complex RhH-{xant(P i Pr 2 ) 2 } (1; xant(P i Pr 2 ) 2 = 9,9-dimethyl-4,5-bis-(diisopropylphosphino)xanthene) activates C−H bonds of arenes. Heating of benzene solutions of 1 at 80 °C affords RhPh{xant(P i Pr 2 ) 2 } (2). Under the same conditions, toluene gives Rh(m-tolyl){xant(P i Pr 2 ) 2 } (3a) and Rh(p-tolyl){xant-(P i Pr 2 ) 2 } (3b) in a 78:22 molar ratio, whereas m-xylene leads to Rh(C 6 H 3 -3,5-Me 2 ){xant(P i Pr 2 ) 2 } (4). At room temperature, fluorobenzene and 1,3-difluorobenzene generate Rh(C 6 H 4 -2-F){xant(P i Pr 2 ) 2 } (5) and Rh(C 6 H 3 -2,6-F 2 ){xant(P i Pr 2 ) 2 } (6), respectively. Complex 1 also promotes the B−H bond activation of pinacolborane (HBpin) and catecholborane (HBcat). The reactions initially give the trans-dihydride derivatives RhH 2 (BR 2 ){xant(P i Pr 2 ) 2 } (BR 2 = Bpin (7), Bcat ( 8)), which lose H 2 to afford the square-planar Rh(BR 2 ){xant(P i Pr 2 ) 2 } (BR 2 = Bpin (9), Bcat ( 10)). Complex 2 reacts with HBpin to regenerate 1 and to give Ph-Bpin. Similarly, complex 9 regenerates 1 and gives Ph-Bpin by reaction with benzene. In agreement with these transformations, complex 1 catalyzes the direct C−H borylation of arenes. The selectivity of the process appears to be governed by the kinetic of the C−H bond activations of the arenes. Benzylic borylation is not observed for methylbenzenes. The first X-ray structure of a square-planar rhodium−boryl complex is also reported.

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Section: Resultsmentioning

confidence: 69%

POP–Rhodium-Promoted C–H and B–H Bond Activation and C–B Bond Formation

2015

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“…Reaction with 1,3difluorobenzene gives the corresponding Os(3,5-C 6 F 2 H 3 ) complex (Scheme 9). 168 4.2. 169 The reaction of a masked two-coordinate (tBu 2 L)Co I complex with fluorinated benzenes results in C− F activation exclusively to yield (tBu 2 L)CoAr and dinuclear [(tBu 2 L)Co(μ-F)] 2 .…”

Section: Chemical Reviewsmentioning

confidence: 99%

Selectivity of C–H Activation and Competition between C–H and C–F Bond Activation at Fluorocarbons

2017

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Partially fluorinated alkanes, arenes, and alkenes can be transformed by a variety of transition metal and lanthanide systems. Although the C-H bond is weaker than the C-F bond regardless of the hybridization of the carbon, the reaction of the C-F bond at the metal is usually more exothermic than the corresponding reaction of the C-H bonds. Both bonds are activated by the metal systems, but the preference for activating these bonds depends on the nature of the hydrocarbon and of the metal system, so that the reaction can be directed exclusively toward C-H or C-F bonds or yield a mixture of products. Additionally, the presence of fluorine differentiates between C-H bonds at different positions resulting in regioselective C-H bond activation; paradoxically, the strongest C-H bond reacts preferentially. The purpose of this review is to describe the field of reactions of partially fluorinated substrates with transition metal atoms, ions, and molecular complexes. The controlling physical properties (thermodynamics and kinetics) are described first, followed by a description of stoichiometric reactions, with the competition between the C-H and C-F activations as focus. A few representative catalytic systems are discussed. The review also highlights the benefit of combining experimental and theoretical studies.

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“…At room temperature, the dihydrogen solvate complex [OsTp(η 2 -H 2 )(OCMe 2 )(P i Pr 3 )]BF 4 ( 430 ) is formed, while at 56 °C the loss of both hydrogen molecules gives rise to the bis-solvento derivative [OsTp(OCMe 2 ) 2 (P i Pr 3 )]BF 4 ( 431 ). The bis-dihydrogen complex 429 reacts with ethylene under 2 atm to afford ethane and [OsTp(CH 2 CH 2 P i Pr 3 )(η 2 -CH 2 CH 2 ) 2 ]BF 4 ( 432 ), which promotes the C–H bond activation of fluorobenzene and 1,3-difluorobenzene by σ-bond metathesis …”

Section: Osmiummentioning

confidence: 99%

“…The bis-dihydrogen complex 429 reacts with ethylene under 2 atm to afford ethane and [OsTp(CH 2 CH 2 P i Pr 3 )(η 2 -CH 2 CH 2 ) 2 ]BF 4 (432), which promotes the C−H bond activation of fluorobenzene and 1,3-difluorobenzene by σ-bond metathesis. 287 Complexes 427−429 have been characterized by X-ray diffraction analysis and DFT calculations. The geometry around the osmium atom of the trihydrides 427 and 428 can be rationalized as a distorted pentagonal bipyramid with the hydride ligands adopting a disposition of local C 2v symmetry, (L 3 )(P i Pr 3 )]Cl (L 3 = TACN (433), TACD (434), BAEA (435)).…”

Section: Complexes With Tris(pyrazoyl)borate and Related Ligandsmentioning

confidence: 99%

Polyhydrides of Platinum Group Metals: Nonclassical Interactions and σ-Bond Activation Reactions

2016

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The preparation, structure, dynamic behavior in solution, and reactivity of polyhydride complexes of platinum group metals, described during the last three decades, are contextualized from both organometallic and coordination chemistry points of view. These compounds, which contain dihydrogen, elongated dihydrogen, compressed dihydride, and classical dihydride ligands promote the activation of B-H, C-H, Si-H, N-H, O-H, C-C, C-N, and C-F, among other σ-bonds. In this review, it is shown that, unlike other more mature areas, the chemistry of polyhydrides offers new exciting conceptual challenges and at the same time the possibility of interacting with other fields including the conversion and storage of regenerative energy, organic synthetic chemistry, drug design, and material science. This wide range of possible interactions foresees promising advances in the near future.

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Reactions of an Osmium Bis(dihydrogen) Complex under Ethylene: Phosphine Addition to a C–C Double Bond and C–H Bond Activation of Fluoroarenes

Cited by 22 publications

References 72 publications

POP–Rhodium-Promoted C–H and B–H Bond Activation and C–B Bond Formation

POP–Rhodium-Promoted C–H and B–H Bond Activation and C–B Bond Formation

Selectivity of C–H Activation and Competition between C–H and C–F Bond Activation at Fluorocarbons

Polyhydrides of Platinum Group Metals: Nonclassical Interactions and σ-Bond Activation Reactions

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