Hydrogen-deuterium exchange between .eta.5-cyclopentadienylbis(ethylene) rhodium and aromatic hydrocarbons

Seiwell, Linda P.

doi:10.1021/ja00829a069

Cited by 25 publications

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“…In this contribution we have applied this strategy to analogous rhodium complexes and have prepared rhodium(I) bis-olefin complexes in which the olefin bears bulky substituents which increases the rate of ligand dissociation and thus finds application in bond activation catalysis. As early as 1974 it was shown that the parent rhodium complex [C 5 H 5 Rh(C 2 H 4 ) 2 ] heated in benzene- d 6 will activate the solvent to reversibly exchange deuterium for hydrogen in the coordinated olefin following a reversible olefin insertion−deinsertion sequence . A mechanism for this exchange process is shown in Scheme and is supported by our investigations with cobalt and earlier work regarding the rhodium bis-ethylene complexes.…”

Section: Introductionsupporting

confidence: 77%

Hydrogen/Deuterium Exchange Reactions and Transfer Hydrogenations Catalyzed by [C₅Me₅Rh(olefin)₂] Complexes: Conversion of Alkoxysilanes to Silyl Enolates

1999

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A series of [C5Me5Rh(CH2CHR)2] complexes (1a − e) have been prepared in which the olefin bears a bulky silyl substituent, R = (a) SiMe3, (b) SiMe2OEt, (c) Si(OiPr)3, (d) SiMe(OSiMe3)2, (e) SiPh2OiPr. The solid-state structure of 1c has been determined by X-ray crystallography. When complex 1a is heated (50 °C) in deuterated solvents (C6D6, C6D5CD3, C6D5Cl, or (CD3)2CO), deuterium is incorporated into the olefinic sites. Thermolysis at higher temperatures results in further H/D exchange and deuteration of both the SiMe3 and C5Me5 groups. Heating 1a in C6D6 with added substrates (aniline, MeOtBu, MeOSiMe3, Cp2Fe, cyclopentene, or EtOAc) results in deuteration of these substrates via shuttling of deuterium from C6D6 to the olefinic sites and then into certain sites of the substrates. Thermolysis of 1a in the presence of vinyltrimethylsilane at higher temperatures results in C−Si bond cleavage and generation of a silacyclopentadiene complex (6) whose structure was determined by X-ray analysis. Thermolysis of 1c in C6D6 results in facile H/D exchange and incorporation of deuterium not only into the vinylic positions but also into the methine and methyl groups of the isopropyl substituents. At 90 °C in the presence of CH2CHSi(OiPr)3 a catalytic transfer hydrogenation is observed which converts the vinylsilane to the silyl enolate, Et(iPrO)2SiOCMeCH2. A series of catalytic transfer hydrogenations were carried out in which alkoxysilanes CH2CHSiMe2OR (R = Et, n-Bu, CHMeEt, C2H4 tBu, C2H4Ph, CHMePh, CHMeCH2Ph) were converted to the corresponding silyl enolates. Catalytic conversion of the vinylaminosilane CH2CHSiMe2NHC2H4Ph to the silyl enamine EtSiMe2NHC2H2Ph is also reported.

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Section: Introductionsupporting

confidence: 77%

Hydrogen/Deuterium Exchange Reactions and Transfer Hydrogenations Catalyzed by [C₅Me₅Rh(olefin)₂] Complexes: Conversion of Alkoxysilanes to Silyl Enolates

1999

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“…Brookhart et al have previously observed deuterium incorporation into the vinylic sites of the olefin ligands of Cp*Co(CH 2 =CHR) 2 (where R = H, SiMe 3 ) following heating of these complexes in d 6 -benzene. 46 Earlier studies by Seiwell 47 found similar H/D exchange with (g 5 -C 5 R 5 )Rh(C 2 H 4 ) 2 (where R = H, Me) when they were heated in d 6 -benzene. In both cases, a mechanism involving solvent coordination to the coordinatively unsaturated [C 5 R 5 M(olefin)] fragment, followed by H/D exchange with the olefin and subsequent elimination of C 6 D 5 H was proposed.…”

Section: Discussionmentioning

confidence: 81%

Photochemical reactions of [CH₂(η⁵-C₅H₄)₂][Rh(C₂H₄)₂]₂with silanes: evidence for Si–C and C–H activation pathways

Cunningham

Duckett

2005

Dalton Trans.

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Photochemical reaction of [CH2(eta5-C5H4)2][Rh(C2H4)2]2 1 with dmso led to the stepwise formation of [CH2(eta5-C5H4)2][Rh(C2H4)2][Rh(C2H4)(dmso)] 2a and [CH2(eta5-C5H4)2][Rh(C2H4)(dmso)]2 2b. Photolysis of 1 with vinyltrimethylsilane ultimately yields three isomeric products of [CH2(eta5-C5H4)2][Rh(CH2=CHSiMe3)2]2, 3a, 3b and 3c which are differentiated by the relative orientations of the vinylsilane. When this reaction is undertaken in d6-benzene, H/D exchange between the solvent and the alpha-proton of the vinylsilane is revealed. In addition evidence for two isomers of the solvent complex [CH2(eta5-C5H4)2][Rh(C2H4)2][Rh(C2H4)(eta2-toluene)] was obtained in these and related experiments when the photolysis was completed at low temperature without substrate, although no evidence for H/D exchange was observed. Photolysis of 1 with Et3SiH yielded the sequential substitution products [CH2(eta5-C5H4)2][Rh(C2H4)2][Rh(C2H4)(SiEt3)H] 4a, [CH2(eta5-C5H4)2][Rh(C2H4)(SiEt3)H]2 4b, [CH2(eta5-C5H4)2][Rh(C2H4)(SiEt3)H][Rh(SiEt3)2(H)2] 4c and [CH2(eta5-C5H4)2][Rh(SiEt3)2(H)2]2 4d; deuteration of the alpha-ring proton sites, and all the silyl protons, of 4d was demonstrated in d6-benzene. This reaction is further complicated by the formation of two Si-C bond activation products, [CH2(eta5-C5H4)2][RhH(mu-SiEt2)]2 5 and [CH2(eta5-C5H4)2][(RhEt)(RhH)(mu-SiEt2)2] 6. Complex 5 was also produced when 1 was photolysed with Et2SiH2. When the photochemical reactions with Et3SiH were repeated at low temperatures, two isomers of the unstable C-H activation products, the vinyl hydrides [CH2(eta5-C5H4)2][{Rh(SiEt3)H}{Rh(SiEt3)}(mu-eta1,eta2-CH=CH2)] 7a and 7b, were obtained. Thermally, 4c was shown to form the ring substituted silyl migration products [(eta5-C5H4)CH2(C5H3SiEt3)][Rh(SiEt3)2(H)2]2 8 while 4b formed [CH2(C5H3SiEt3)2][Rh(SiEt3)2(H)2]2 (9a and 9b) upon reaction with excess silane. The corresponding photochemical reaction with Me3SiH yielded the expected products [CH2(eta5-C5H4)2][Rh(C2H4)2][Rh(C2H4)(SiMe3)H] 10a, [CH2(eta5-C5H4)2][Rh(C2H4)(SiMe3)H]2 10b, [CH2(eta5-C5H4)2][Rh(C2H4)(SiMe3)H][Rh(SiMe3)2(H)2] 10c and [CH2(eta5-C5H4)2][Rh(SiMe3)2(H)2]2 10d. However, three Si-C bond activation products, [CH2(eta5-C5H4)2][(RhMe)(RhH)(mu-SiMe2)2] 11, [CH2(eta5-C5H4)2][(Rh{SiMe3})(RhMe)(mu-SiMe2)2] 12 and [CH2(eta5-C5H4)2][(Rh{SiMe3})(RhH)(mu-SiMe2)2] 13 were also obtained in these reactions.

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“…(C 5 Me 5 )Rh(C 2 H 4 ) 2 ( 1 ) can lose ethylene to provide two coordination sites and is known to activate C−H bonds, making this complex a prime candidate for C−C activation. Reactions carried out with 1 or its analog (C 5 Me 5 )Co(C 2 H 4 ) 2 ( 2 ) and thiophenes have demonstrated the ability of these complexes to perform C−S activation (Scheme ) .…”

Section: Introductionmentioning

confidence: 99%

C−C Activation in Biphenylene. Synthesis, Structure, and Reactivity of (C₅Me₅)₂M₂(2,2‘-biphenyl) (M = Rh, Co)

et al. 1997

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Carbon−carbon bond cleavage of biphenylene was achieved with (C5Me5)M(C2H4)2 (M = Rh, Co) to give the bimetallic species (C5Me5)2M2(2,2‘-biphenyl). The isomorphous solid state X-ray structures of these complexes showed the biphenyl substrate to be σ-coordinated to one metal and η4-bound to the other. These complexes display dynamic behavior, interchanging the σ- and π-bonding. Variable-temperature NMR studies were performed on both binuclear species, and the energy barrier for interconversion of the two (C5Me5) fragments was calculated to be ΔG ⧧ (350 K) = 16.8 kcal/mol and ΔG ⧧ (248 K) = 11.4 kcal/mol for the rhodium and cobalt complexes, respectively. (C5Me5)2Rh2(2,2‘-biphenyl) reacted with CO to give (C5Me5)Rh(CO)2 and (C5Me5)Rh(CO)(2,2‘-biphenyl), while the cobalt analog gave (C5Me5)Co(CO)2 and fluorenone. (C5Me5)2Co2(2,2‘-biphenyl) gave (C5Me5)Co(PMe3)2 and (C5Me5)Co(PMe3)(2,2‘-biphenyl) when reacted with PMe3, as determined by X-ray crystallography of the latter complex. Both complexes were found to be resistant to hydrogenation.

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Hydrogen-deuterium exchange between .eta.5-cyclopentadienylbis(ethylene) rhodium and aromatic hydrocarbons

Cited by 25 publications

References 0 publications

Hydrogen/Deuterium Exchange Reactions and Transfer Hydrogenations Catalyzed by [C₅Me₅Rh(olefin)₂] Complexes: Conversion of Alkoxysilanes to Silyl Enolates

Hydrogen/Deuterium Exchange Reactions and Transfer Hydrogenations Catalyzed by [C₅Me₅Rh(olefin)₂] Complexes: Conversion of Alkoxysilanes to Silyl Enolates

Photochemical reactions of [CH₂(η⁵-C₅H₄)₂][Rh(C₂H₄)₂]₂with silanes: evidence for Si–C and C–H activation pathways

C−C Activation in Biphenylene. Synthesis, Structure, and Reactivity of (C₅Me₅)₂M₂(2,2‘-biphenyl) (M = Rh, Co)

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Hydrogen-deuterium exchange between .eta.5-cyclopentadienylbis(ethylene) rhodium and aromatic hydrocarbons

Cited by 25 publications

References 0 publications

Hydrogen/Deuterium Exchange Reactions and Transfer Hydrogenations Catalyzed by [C5Me5Rh(olefin)2] Complexes: Conversion of Alkoxysilanes to Silyl Enolates

Hydrogen/Deuterium Exchange Reactions and Transfer Hydrogenations Catalyzed by [C5Me5Rh(olefin)2] Complexes: Conversion of Alkoxysilanes to Silyl Enolates

Photochemical reactions of [CH2(η5-C5H4)2][Rh(C2H4)2]2with silanes: evidence for Si–C and C–H activation pathways

C−C Activation in Biphenylene. Synthesis, Structure, and Reactivity of (C5Me5)2M2(2,2‘-biphenyl) (M = Rh, Co)

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Hydrogen/Deuterium Exchange Reactions and Transfer Hydrogenations Catalyzed by [C₅Me₅Rh(olefin)₂] Complexes: Conversion of Alkoxysilanes to Silyl Enolates

Hydrogen/Deuterium Exchange Reactions and Transfer Hydrogenations Catalyzed by [C₅Me₅Rh(olefin)₂] Complexes: Conversion of Alkoxysilanes to Silyl Enolates

Photochemical reactions of [CH₂(η⁵-C₅H₄)₂][Rh(C₂H₄)₂]₂with silanes: evidence for Si–C and C–H activation pathways

C−C Activation in Biphenylene. Synthesis, Structure, and Reactivity of (C₅Me₅)₂M₂(2,2‘-biphenyl) (M = Rh, Co)