Participation of hydrogen bonds in the protonation of (?5-C5Me5)M(CO)2, M=Ir, Rh

Shubina, Elena S.; Крылов, А. Н.; Muratov, Dmitry V.; Fil'chikov, A. A.; Epstein, Lina M.

doi:10.1007/bf00699018

Cited by 8 publications

(7 citation statements)

References 4 publications

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“…The concentration dependence of ν CO of 2d and ν OCO as of 6d anion bands confirms this conclusion. The existence of the equilibrium between free cation and ion pair Cp*M(CO) 2 H + ··· − OOCCF 3 was established before for protonation of Cp*M(CO) 2 (M = Rh, Ir) with CF 3 COOH ( 2d ),36−38 and the spectral changes were similar to those observed here. The proton transfer to the metal atom has been shown to cause a large high‐frequency shift of the ν CO bands (Δν = +95 to +143 cm −1 ).…”

Section: Discussionsupporting

confidence: 84%

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

Belkova

Ionidis

Epstein

et al. 2001

Eur. J. Inorg. Chem.

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The interaction of the ruthenium hydride complex RuH ≡ CpRuH(CO)(PCy3) (1) with various proton donors AH ≡ CF3CH2OH (2a), (CF3)2CHOH (2b), (CF3)3COH (2c), CF3COOH (2d), and HBF4 (2e) has been studied by variable‐temperature IR spectroscopy using hexane and CH2Cl2 as solvents of different polarity. A low‐temperature NMR study of the interaction of 1 with 2c was performed using [D8]methylcyclohexane, CD2Cl2, and a liquefied mixture of CDF2Cl/CDF3 (2:1). The first stage of the proton transfer process was found to be the formation of hydrogen‐bonded complexes of the type RuH···HA. The hydrogen bonds in these complexes are of medium strength (−ΔH° = 5.3−7.6 kcal mol−1). The second stage is the slow conversion of the H‐complex to a dihydrogen complex to which a hydrogen‐bonded ion‐pair structure [Ru(η2‐H2)]+···A− was assigned. The kinetics of this unusually slow proton transfer reaction was monitored in the case of 2c at 200 K in CH2Cl2. Fast protonation of 1 by 2d leads additionally to a species assigned as the free cationic complex [Ru(η2‐H2)]+, whose formation is driven by the formation of the homoconjugated anionic complex [AHA]−. At temperatures above 220 K both the hydrogen‐bonded ion pair and the free cationic complex easily release dihydrogen, producing RuA.

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Section: Discussionsupporting

confidence: 84%

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

Belkova

Ionidis

Epstein

et al. 2001

Eur. J. Inorg. Chem.

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“…In an MH···HA dihydrogen bond, [7,8] electrons come from a s bonding electron pair of an MÀH bond localized mainly on the hydride ligand. [13] In the same way, hydrogen bonding to metal atoms was found to intermediate metal protonation of transition metal complexes, [14][15][16] and dihydrogen bonding was shown to precede hydride ligand protonation yielding h 2 -H 2 complexes. [1,2,7,[10][11][12] In this case electrons of filled d orbitals of the metal are donated to s Ã AH .…”

Section: Introductionmentioning

confidence: 82%

“…[2] Hydrogen bonds play a key role as initial stage of the proton-transfer reaction to organic bases. [13] In the same way, hydrogen bonding to metal atoms was found to intermediate metal protonation of transition metal complexes, [14][15][16] and dihydrogen bonding was shown to precede hydride ligand protonation yielding h 2 -H 2 complexes. [7,17] Basic knowledge accumulated over the last two decades suggests that a direct proton transfer to a metal lone pair is an unlikely event in the presence of hydride ligands, which are considered to be the kinetic site of proton attack even if classical di(poly)hydride were the thermodynamic protonation product.…”

Section: Introductionmentioning

confidence: 82%

Directionality of Dihydrogen Bonds: The Role of Transition Metal Atoms

Filippov¹,

Belkova²,

Epstein³

et al. 2012

ChemPhysChem

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A theoretical study on two series of electron-rich group 8 hydrides is carried out to evaluate involvement of the transition metal in dihydrogen bonding. To this end, the structural and electronic parameters are computed at the DFT/B3PW91 level for hydrogen-bonded adducts of [(PP(3))MH(2)] and [Cp*MH(dppe)] (M = Fe, Ru, Os; PP(3) = κ(4)-P(CH(2)CH(2)PPh(2))(3), dppe = κ(2)-Ph(2)PCH(2)CH(2)PPh(2)) with CF(3)CH(2)OH (TFE) as proton donor. The results are compared with those of adduct [Cp(2)NbH(3)]⋅TFE featuring a "pure" dihydrogen bond, and classical hydrogen bonds in pyridine⋅TFE and Me(3)N⋅TFE. Deviation of the H⋅⋅⋅H-A fragment from linearity is shown to originate from the metal participation in dihydrogen bonding. The latter is confirmed by the electronic parameters obtained by NBO and AIM analysis. Considered together, orbital interaction energies and hydrogen bond ellipticity are salient indicators of this effect and allow the MH⋅⋅⋅HA interaction to be described as a bifurcate hydrogen bond. The impact of the M⋅⋅⋅HA interaction is shown to increase on descending the group, and this explains the experimental trends in mechanisms of proton-transfer reactions via MH⋅⋅⋅HA intermediates. Strengthening of the M⋅⋅⋅H interaction in the case of electron-rich 5d metal hydrides leads to direct proton transfer to the metal atom.

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“…Hydrogen-bonding interaction at the O CO site would anyway be expected to cause a band shift in the direction opposite to what was observed [29]. Similarly when the tungsten center of 1 would get involved in hydrogen bonding with a proton donor, the m(CO), m(WH) and m(NO) bands are expected to be shifted toward higher wave numbers by Dm = +100-150 cm À1 [18][19][20]28,29]. No such bands were observed in the IR spectra in the presence of TMP concluding that such hydrogen bonding is not occurring.…”

Section: Ir Spectroscopic Investigationsmentioning

confidence: 79%

“…Therefore we found it intriguing to trace the nature of these hydrogen bonding equilibria between 1 and the protic donors by quantitative variable temperature IR and NMR methodologies [2][3][4][5][6][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The experiments were carried out in hexane using protic donors of substantially different pK a values (isopropanol, pK a = 17; benzylalcohol, pK a = 15 and 3,4,5-trimethylphenol, pK a = 10.6) in the temperature range from 213 to 293 K. The short time scale set by the IR pursuit was expected to allow detection of the hydrogen bonded intermediates.…”

Section: Hydrogen Bonding Of 1 With Protic Donors: Vt Ir and Vt Nmr Smentioning

confidence: 99%

Hydridic reactivity of W(CO)(H)(NO)(PMe3)3 – Dihydrogen bonding and H2 formation with protic donors

Avramović

Höck

Blacque

et al. 2010

Journal of Organometallic Chemistry

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Participation of hydrogen bonds in the protonation of (?5-C5Me5)M(CO)2, M=Ir, Rh

Cited by 8 publications

References 4 publications

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

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

Directionality of Dihydrogen Bonds: The Role of Transition Metal Atoms

Hydridic reactivity of W(CO)(H)(NO)(PMe3)3 – Dihydrogen bonding and H2 formation with protic donors

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