Proton Transfer to CpRuH(CO)(PCy3) Studied by Low-Temperature IR and NMR Spectroscopy

Belkova, Natalia V.; Ionidis, A. V.; Epstein, Lina M.; Shubina, Elena S.; Gruendemann, S.; Golubev, N. S.; Limbach, Hans−Heinrich

doi:10.1002/1099-0682(200107)2001:7<1753::aid-ejic1753>3.0.co;2-h

Cited by 42 publications

(50 citation statements)

References 45 publications

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“…In many cases, however, basic anions (A – = OR – , OCOR – ) tend to displace H 2 out of the transition metal coordination sphere, yielding organyloxo products. This is the case for the protonation products of complexes [(triphos)ReH(CO) 2 ],62 [Re(CO)H 2 (NO)(PR 3 ) 2 ],63 and [CpRuH(CO)(PCy 3 )],64 for which the corresponding [M(η 2 ‐H 2 )] + cations could be isolated as [BF 4 ] – salts but evolved into [MA] species in the presence of fluorinated alcohols or carboxylic acids. In contrast to the isomerization process, this reaction proceeds intramolecularly and does not require a hydrogen bonded ion pair dissociation 64…”

Section: Ion Pairing and Subsequent Transformations Of [M(η2‐h2)]+ Comentioning

confidence: 99%

“…The transition state can be regarded as an H 2 entity (H–H length ca. 0.9 Å) simultaneously bonded to both the [M] + and the [AHA] – units (M–H and H–O distances are ca 1.6 and 1.4 Å, respectively) 25,32,35. In the work of Feracin et al the proton transfer from CF 3 COOH to [ReH 2 (CO)(NO)(PR 3 ) 2 ] is reported as having positive Δ H ‡ and Δ S ‡ 10,51.…”

Section: Kinetics and Thermodynamics Of Proton Transfer Via Dihydrogementioning

confidence: 99%

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Dihydrogen Bonding, Proton Transfer and Beyond: What We Can Learn from Kinetics and Thermodynamics

2010

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Hydrogen bonding to transition metal hydride complexes and its role in the proton transfer process has been a subject of the authors' research interest in recent years. The present microreview analyzes the relationships of kinetic and thermodynamic parameters of dihydrogen bonding, MH···HA, proton transfer, yielding [M(η2‐H2)] species, and subsequent steps such as [M(η2‐H2)] to [M(H)2] isomerization or H2 evolution on the basis of all data acquired so far. It aims at showing the factors that determine the stability of the species involved, the physico‐chemical (thermodynamic and kinetic) origin of the effects observed, and, ideally, allow one to better govern the hydrides reactivity.

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Section: Ion Pairing and Subsequent Transformations Of [M(η2‐h2)]+ Comentioning

confidence: 99%

Section: Kinetics and Thermodynamics Of Proton Transfer Via Dihydrogementioning

confidence: 99%

Dihydrogen Bonding, Proton Transfer and Beyond: What We Can Learn from Kinetics and Thermodynamics

2010

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“…Interaction of [NEt 4 ][HRe 2 (CO) 9 ] with TFE : The addition of [NEt 4 ]‐ 1 19 (up to 0.1 m ) to CH 2 Cl 2 solutions of TFE (0.02 m ) at room temperature did not cause any appreciable change in the ν OH region of the IR spectrum, at variance with what was previously observed for many neutral hydrido complexes 5a. 6f,6k An analogous room‐temperature experiment with an excess of TFE ([NEt 4 ]‐ 1 6×10 −3 m , TFE 0.1 m ) did not show any change in the ν CO region. This indicated that the proton–hydride interaction was either absent or weaker than in these previous cases.…”

Section: Resultsmentioning

confidence: 54%

NMR Investigation of the Dihydrogen‐Bonding and Proton‐Transfer Equilibria between the Hydrido Carbonyl Anion [HRe₂(CO)₉]⁻ and Fluorinated Alcohols

Donghi

Beringhelli

D’Alfonso

et al. 2006

Chemistry A European J

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The interaction of fluorinated alcohols with the anionic hydrido complex [HRe2(CO)9]- (1) has been investigated by NMR spectroscopy. According to the acidic strength of the alcohols, the interaction may result not only in the formation of dihydrogen-bonded ROH...[HRe2(CO)9]- adducts 2, but also in proton transfer to give the neutral species [H2Re2(CO)9] (3). With the weaker acid trifluoroethanol (TFE) evidence for the occurrence of the dihydrogen-bonding equilibrium was obtained by 2D 1H NOESY. The dependence of the hydride chemical shift on TFE concentration at different temperatures provided values for the constants of this equilibrium, from which the thermodynamic parameters were evaluated as deltaH(degrees) = -2.6(2) kcal mol(-1), deltaS(degrees) = -9.3(2) cal mol(-1) K(-1). This corresponds to a rather low basicity factor (E(j) = 0.64). Variable-temperature T1 measurements allowed the proton-hydride distance in adduct 2 a to be estimated (1.80 angstroms). In the presence of hexafluoroisopropyl alcohol (HFIP) simultaneous occurrence of both dihydrogen-bonding and proton-transfer equilibria was observed, and the equilibria shifted versus the protonated product 3 with increasing HFIP concentration and decreasing temperature. Reversible proton transfer between the alcohol and the hydrido complex occurs on the NMR timescale, as revealed by a 2D 1H EXSY experiment at 240 K. For the more acidic perfluoro-tert-butyl alcohol (PFTB) the protonation equilibrium was further shifted to the right. Thermal instability of 3 prevented the acquisition of accurate thermodynamic data for these equilibria. The occurrence of the proton-transfer processes (in spite of the unfavorable pK(a) values) can be explained by the formation of homoconjugated RO...HOR- pairs which stabilize the alcoholate anions.

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“…24 In turn, introduction of elec tron withdrawing carbonyl ligands into cyclopentadienyl complexes decreases the basicity of the hydride ligand (E j = 1.02 for CpRuH(CO)(PCy 3 )). 25 In contrast, the ba sicity increases when the Cp ligand is replaced by penta methylcyclopentadienyl (Cp*; E j = 1.38). 4 Thus, the pro ton accepting ability (E j ) increases in the following order: TpRuH(dppe) < CpRuH(CO)(PCy 3 ) < CpRuH(dppe) < < Cp*RuH(dppe).…”

Section: Resultsmentioning

confidence: 99%

Dihydrogen bonding formed by (hydrido)[hydrotris(pyrazolyl)borato]ruthenium. The effect of ligands on the proton-accepting ability of ruthenium complexes

et al. 2014

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Reactions of [1,2 bis(diphenylphosphino)ethane](hydrido)[hydrotris(pyrazolyl)borato] ruthenium with proton donors were studied by IR and 1 H NMR spectroscopy in CH 2 Cl 2 over a wide temperature range. Dihydrogen bonding to CF 3 CH 2 OH was detected; its spectral and thermodynamic parameters (H = -3.3±0.2 kcal mol -1 , S = -6.7±0.6 cal mol -1 K -1 ) were determined. The basicity factor E j of the hydride ligand is 0.81. The H ... H distance in the dihydrogen bonded complex (2.05 Å) was estimated from the changes in the spin lattice relax ation time T 1min of the hydride resonance. Comparison of the results obtained with the litera ture data revealed a correlation between the length and enthalpy of formation of the dihydrogen bond as well as a correlation between the basicity of the hydride ligand and the tendency of the fragment [ML n ] toward stabilization and oxidative addition of H 2 .Hydrotris(pyrazolyl)borates (Tp) are anionic ligands often considered to be analogs of cyclopentadienyl ones (Cp). 1 Indeed, such ligands are formally donors of six electrons and occupy three coordination sites in metal complexes. According to electrochemical data for the com plexes TpMH(PPh 3 ) 2 and CpMH(PPh 3 ) 2 (M = Ru and Os), the oxidation potentials of the Tp and Cp complexes of the same metals are close. 2 However, the ligands of the two types do differ in electronic, steric, and coordination properties. For instance, this difference is manifested by the ability to stabilize complexes with molecular hydrogen. The well known cationic complexes of the [(C 5 R 5 )MH 2 (L)(L´)] + type (M = Fe, Ru, and Os) can have both a classical dihydride structure, [(C 5 R 5 )M(H) 2 (L)(L´)] + , and a nonclassical structure containing molecular hydrogen, [(C 5 R 5 )M( 2 H 2 ) (L)(L´)] + . 3-8 Similar complexes with the Tp ligand do always have nonclassical structures. 2, [9][10][11] Earlier, 12,13 we have demonstrated that hydrogen bond ing (MH ... HX) to a hydride ligand precedes proton trans fer giving rise to complexes with molecular hydrogen. The ligand environment is crucial for both the proton accept ing ability of the hydride ligand and the stability of the complexes MH ... HX formed by dihydrogen bonds (DHB) 14 as well as for the stability of complexes with molecular hydrogen. 1,15 As a next step in our investigations of hydrogen bonds and proton transfer to transition metal hydrides, here we studied reactions of the ruthenium(II) hydride TpRuH(dppe) (1; dppe =  2 Ph 2 PCH 2 CH 2 PPh 2 ) with proton donors in order to examine the effect of the ligand on the basicity (proton accepting ability) and protonation of transition metal hydrides. Results and Discussion

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Proton Transfer to CpRuH(CO)(PCy3) Studied by Low-Temperature IR and NMR Spectroscopy

Cited by 42 publications

References 45 publications

Dihydrogen Bonding, Proton Transfer and Beyond: What We Can Learn from Kinetics and Thermodynamics

Dihydrogen Bonding, Proton Transfer and Beyond: What We Can Learn from Kinetics and Thermodynamics

NMR Investigation of the Dihydrogen‐Bonding and Proton‐Transfer Equilibria between the Hydrido Carbonyl Anion [HRe₂(CO)₉]⁻ and Fluorinated Alcohols

Dihydrogen bonding formed by (hydrido)[hydrotris(pyrazolyl)borato]ruthenium. The effect of ligands on the proton-accepting ability of ruthenium complexes

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Proton Transfer to CpRuH(CO)(PCy3) Studied by Low-Temperature IR and NMR Spectroscopy

Cited by 42 publications

References 45 publications

Dihydrogen Bonding, Proton Transfer and Beyond: What We Can Learn from Kinetics and Thermodynamics

Dihydrogen Bonding, Proton Transfer and Beyond: What We Can Learn from Kinetics and Thermodynamics

NMR Investigation of the Dihydrogen‐Bonding and Proton‐Transfer Equilibria between the Hydrido Carbonyl Anion [HRe2(CO)9]− and Fluorinated Alcohols

Dihydrogen bonding formed by (hydrido)[hydrotris(pyrazolyl)borato]ruthenium. The effect of ligands on the proton-accepting ability of ruthenium complexes

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NMR Investigation of the Dihydrogen‐Bonding and Proton‐Transfer Equilibria between the Hydrido Carbonyl Anion [HRe₂(CO)₉]⁻ and Fluorinated Alcohols