Indenyl complexes of Group 9 metals: Synthetic and catalytic chemistry

Kharitonov, Vladimir B.; Muratov, Dmitry V.; Loginov, Dmitry A.

doi:10.1016/j.ccr.2019.213027

Cited by 27 publications

(10 citation statements)

References 269 publications

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“…Instead, only partial consumption of the starting materials was evident along with the generation of a complex mixture of products. This demonstrated that [Rh(Ind)(C 2 H 4 ) 2 ] reacts much more readily with SIPr than the Cp* analogue, a manifestation of the “indenyl effect” where auxiliary ligand substitution is accelerated as a result of η 3 coordination of the indenyl ligand driven by recovery of benzene ring aromaticity [33a] . A single crystal X‐ray diffraction study identified 10 as one of products from the reaction and provided evidence for one of the pathways involving loss of one ethylene ligand, C−H activation of the other and loss of two H atoms to generate a Rh−Rh bonded dimer with bridging σ,π‐vinyl ligands (see the Supporting Information for structure).…”

Section: Resultsmentioning

confidence: 99%

“…This demonstrated that [Rh(Ind)(C 2 H 4 ) 2 ] reacts much more readily with SIPr than the Cp* analogue, a manifestation of the “indenyl effect” where auxiliary ligand substitution is accelerated as a result of η 3 coordination of the indenyl ligand driven by recovery of benzene ring aromaticity. [33a] A single crystal X‐ray diffraction study identified 10 as one of products from the reaction and provided evidence for one of the pathways involving loss of one ethylene ligand, C−H activation of the other and loss of two H atoms to generate a Rh−Rh bonded dimer with bridging σ,π‐vinyl ligands (see the Supporting Information for structure). This structure is very similar to products formed in the reaction of [Rh(Ind)(C 2 H 4 ) 2 ] or [Rh(1‐MeInd)(C 2 H 4 ) 2 ] with Me−C≡C−Me, which gave a Rh dimer containing one bridging vinyl and one bridging 1,2‐dimethylvinyl ligand.…”

Section: Resultsmentioning

confidence: 99%

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Rhodium Indenyl NHC and Fluorenyl‐Tethered NHC Half‐Sandwich Complexes: Synthesis, Structures and Applications in the Catalytic C−H Borylation of Arenes and Alkanes

Evans

Morton

Luz

et al. 2021

Chemistry A European J

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Indenyl (Ind) rhodium N‐heterocyclic carbene (NHC) complexes [Rh(η5‐Ind)(NHC)(L)] were synthesised for 1,3‐bis(2,6‐diisopropylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIPr) with L=C2H4 (1), CO (2 a) and cyclooctene (COE; 3), for 1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIMes) with L=CO (2 b) and COE (4), and 1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene (IMes) with L=CO (2 c) and COE (5). Reaction of SIPr with [Rh(Cp*)(C2H4)2] did not give the desired SIPr complex, thus demonstrating the “indenyl effect” in the synthesis of 1. Oxidative addition of HSi(OEt)3 to 3 proceeded under mild conditions to give the Rh silyl hydride complex [Rh(Ind){Si(OEt)3}(H)(SIPr)] (6) with loss of COE. Tethered‐fluorenyl NHC rhodium complexes [Rh{(η5‐C13H8)C2H4N(C)C2HxNR}(L)] (x=4, R=Dipp, L=C2H4: 11; L=COE: 12; L=CO: 13; R=Mes, L=COE: 14; L=CO: 15; x=2, R=Me, L=COE: 16; L=CO: 17) were synthesised in low yields (5–31 %) in comparison to good yields for the monodentate complexes (49–79 %). Compounds 3 and 1, which contain labile alkene ligands, were successful catalysts for the catalytic borylation of benzene with B2pin2 (Bpin=pinacolboronate, 97 and 93 % PhBpin respectively with 5 mol % catalyst, 24 h, 80 °C), with SIPr giving a more active catalyst than SIMes or IMes. Fluorenyl‐tethered NHC complexes were much less active as borylation catalysts, and the carbonyl complexes were inactive. The borylation of toluene, biphenyl, anisole and diphenyl ether proceeded to give meta substitutions as the major product, with smaller amounts of para substitution and almost no ortho product. The borylation of octane and decane with B2pin2 at 120 and 140 °C, respectively, was monitored by 11B NMR spectroscopy, which showed high conversions into octyl and decylBpin over 4–7 days, thus demonstrating catalysed sp3 C−H borylation with new piano stool rhodium indenyl complexes. Irradiation of the monodentate complexes with 400 or 420 nm light confirmed the ready dissociation of C2H4 and COE ligands, whereas CO complexes were inert. Evidence for C−H bond activation in the alkyl groups of the NHC ligands was obtained.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Rhodium Indenyl NHC and Fluorenyl‐Tethered NHC Half‐Sandwich Complexes: Synthesis, Structures and Applications in the Catalytic C−H Borylation of Arenes and Alkanes

Evans

Morton

Luz

et al. 2021

Chemistry A European J

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“…In particular, indenyl is capable to provide an additional free coordination site at a metal atom as a result of an easy slippage of indenyl ligand from η 5 to η 3 coordination mode (the so called “indenyl effect”) [7] . However, this flexibility leads to a weakening of the metal‐indenyl bond, which limits the catalytic applications of indenyl complexes [6a] . For example, while rhodium complexes with the parent unsubstituted indenyl ligand C 9 H 7 efficiently catalyze the reductive amination of carbonyl compounds, [8] they are almost inactive in the oxidative coupling of benzoic acids with alkynes due to the loss of the indenyl ligand [8a] .…”

Section: Introductionmentioning

confidence: 99%

Easy Access to Versatile Catalytic Systems for C−H Activation and Reductive Amination Based on Tetrahydrofluorenyl Rhodium(III) Complexes

Kharitonov

Runikhina

Nelyubina

et al. 2021

Chemistry A European J

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On the basis of the 1,2,3,4-tetrahydrofluorenyl ligand, a simple approach was developed to new effective rhodium catalysts for the construction of CÀ C and CÀ N bonds. The halide compounds [(η 5 -tetrahydrofluorenyl)RhX 2 ] 2 (2 a: X = Br; 2 b: X = I) were synthesized by treatment of the bis (ethylene) derivative (η 5 -tetrahydrofluorenyl)Rh(C 2 H 4 ) 2 (1 a) with halogens. An analogous reaction of the cyclooctadiene complex (η 5 -tetrahydrofluorenyl)Rh(cod) (1 b) with I 2 is complicated by the side formation of [(cod)RhI] 2 . The reaction of 2 b with 2,2'-bipyridyl leads to cation [(η 5 -tetrahydrofluorenyl) Rh(2,2'-bipyridyl)I] + (3). The halide abstraction from 2 a,b with thallium or silver salts allowed us to prepare sandwich compounds with incoming cyclopentadienyl, dicarbollide and mesityleneligands [(η 5 -tetrahydrofluorenyl)RhCp] + (4), (η 5 -tet-rahydrofluorenyl)Rh(η-7,8-C 2 B 9 H 11 ) (5), and [(η 5 -tetrahydrofluorenyl)Rh(η-mesitylene)] 2 + (6). The structures of 1 b, 2 b • 2I 2 , 3PF 6 , 4TlI 4 , 5, and [(cod)RhI] 2 were determined by X-ray diffraction. Compounds 2 a,b efficiently catalyze the oxidative coupling of benzoic acids with alkynes to selectively give isocoumarins or naphthalenes, depending on the reaction temperature. Moreover, they showed moderate catalytic activity in other annulations of alkynes with aromatic compounds (such as benzamide, acetanilide, etc.) which proceed through CH activation. Compound 2 b also effectively catalyzes the reductive amination of aldehydes and ketones in the presence of carbon monoxide and water via water-gas shift reaction, giving amines in high yields (67-99 %).

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“…In fact, the substitution of COD in half-sandwich complexes is typically used for the preparation of organometallic derivatives for catalytic studies. 11–17 It was shown later that this type of reactivity was observed for the pentamethylated analogue of 1 ( i.e. , [Cp*Ir(COD)Br] + ( 3 ) transforms into [Cp*Ir(P(OMe) 3 ) 2 Br] + ( 4 ) under the same conditions).…”

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confidence: 85%

Teaching cyclopentadienyl how to leave: a case study of the [CpIr(COD)Br]⁺ complex

Chamkin

2022

New J. Chem.

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Indenyl complexes of Group 9 metals: Synthetic and catalytic chemistry

Cited by 27 publications

References 269 publications

Rhodium Indenyl NHC and Fluorenyl‐Tethered NHC Half‐Sandwich Complexes: Synthesis, Structures and Applications in the Catalytic C−H Borylation of Arenes and Alkanes

Rhodium Indenyl NHC and Fluorenyl‐Tethered NHC Half‐Sandwich Complexes: Synthesis, Structures and Applications in the Catalytic C−H Borylation of Arenes and Alkanes

Easy Access to Versatile Catalytic Systems for C−H Activation and Reductive Amination Based on Tetrahydrofluorenyl Rhodium(III) Complexes

Teaching cyclopentadienyl how to leave: a case study of the [CpIr(COD)Br]⁺ complex

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Indenyl complexes of Group 9 metals: Synthetic and catalytic chemistry

Cited by 27 publications

References 269 publications

Rhodium Indenyl NHC and Fluorenyl‐Tethered NHC Half‐Sandwich Complexes: Synthesis, Structures and Applications in the Catalytic C−H Borylation of Arenes and Alkanes

Rhodium Indenyl NHC and Fluorenyl‐Tethered NHC Half‐Sandwich Complexes: Synthesis, Structures and Applications in the Catalytic C−H Borylation of Arenes and Alkanes

Easy Access to Versatile Catalytic Systems for C−H Activation and Reductive Amination Based on Tetrahydrofluorenyl Rhodium(III) Complexes

Teaching cyclopentadienyl how to leave: a case study of the [CpIr(COD)Br]+ complex

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Teaching cyclopentadienyl how to leave: a case study of the [CpIr(COD)Br]⁺ complex