Synthesis of the acidic dihydrogen complexes trans-[M(H2)(CN)L2]+ and trans-[M(H2)(CNH)L2]2+ where M = Fe, Ru, Os and L = dppm, dppe, dppp, depe, and dihydrogen substitution by the trifluoromethanesulfonate anion to give trans-[Ru(OTf )(CN)L2] or trans-[Ru(OTf )(CNH)L2]OTf †

Fong, Tina P.; Forde, Cameron E.; Lough, Alan J.; Morris, Robert H.; Rigo, Pierluigi; Rocchini, Eliana; Stephan, Thomas

doi:10.1039/a906717e

Cited by 64 publications

(52 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[24] Influence of homoconjugated anionic species [RO¥¥¥H¥¥¥OR] À on the protonation: The importance of the homoconjugate pairs formed by the acid and its conjugate base in the protonation processes of transitionmetal hydrides is becoming recognised. [25] The production of such species has been regarded as the driving force of the protonation reaction with not very strong acids. [26] Protonation of the trihydride by TFA has been proposed as the first step of the reaction.…”

Section: Proton Transfer From Hmentioning

confidence: 99%

First Investigation of Non‐Classical Dihydrogen Bonding between an Early Transition‐Metal Hydride and Alcohols: IR, NMR, and DFT Approach

Bakhmutova

Bakhmutov

Belkova

et al. 2004

Chemistry A European J

View full text Add to dashboard Cite

The interaction of [NbCp(2)H(3)] with fluorinated alcohols to give dihydrogen-bonded complexes was studied by a combination of IR, NMR and DFT methods. IR spectra were examined in the range from 200-295 K, affording a clear picture of dihydrogen-bond formation when [NbCp(2)H(3)]/HOR(f) mixtures (HOR(f) = hexafluoroisopropanol (HFIP) or perfluoro-tert-butanol (PFTB)) were quickly cooled to 200 K. Through examination of the OH region, the dihydrogen-bond energetics were determined to be 4.5+/-0.3 kcal mol(-1) for TFE (TFE = trifluoroethanol) and 5.7+/-0.3 kcal mol(-1) for HFIP. (1)H NMR studies of solutions of [NbCp(2)H(2)(B)H(A)] and HFIP in [D(8)]toluene revealed high-field shifts of the hydrides H(A) and H(B), characteristic of dihydrogen-bond formation, upon addition of alcohol. The magnitude of signal shifts and T(1) relaxation time measurements show preferential coordination of the alcohol to the central hydride H(A), but are also consistent with a bifurcated character of the dihydrogen bonding. Estimations of hydride-proton distances based on T(1) data are in good accord with the results of DFT calculations. DFT calculations for the interaction of [NbCp(2)H(3)] with a series of non-fluorinated (MeOH, CH(3)COOH) and fluorinated (CF(3)OH, TFE, HFIP, PFTB and CF(3)COOH) proton donors of different strengths showed dihydrogen-bond formation, with binding energies ranging from -5.7 to -12.3 kcal mol(-1), depending on the proton donor strength. Coordination of proton donors occurs both to the central and to the lateral hydrides of [NbCp(2)H(3)], the former interaction being of bifurcated type and energetically slightly more favourable. In the case of the strong acid H(3)O(+), the proton transfer occurs without any barrier, and no dihydrogen-bonded intermediates are found. Proton transfer to [NbCp(2)H(3)] gives bis(dihydrogen) [NbCp(2)(eta(2)-H(2))(2)](+) and dihydride(dihydrogen) complexes [NbCp(2)(H)(2)(eta(2)-H(2))](+) (with lateral hydrides and central dihydrogen), the former product being slightly more stable. When two molecules of TFA were included in the calculations, in addition to the dihydrogen-bonded adduct, an ionic pair formed by the cationic bis(dihydrogen) complex [NbCp(2)(eta(2)-H(2))(2)](+) and the homoconjugated anion pair (CF(3)COO...H...OOCCF(3))(-) was found as a minimum. It is very likely that these ionic pairs may be intermediates in the H/D exchange between the hydride ligands and the OD group observed with the more acidic alcohols in the NMR studies.

show abstract

Section: Proton Transfer From Hmentioning

confidence: 99%

First Investigation of Non‐Classical Dihydrogen Bonding between an Early Transition‐Metal Hydride and Alcohols: IR, NMR, and DFT Approach

Bakhmutova

Bakhmutov

Belkova

et al. 2004

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…[3][4][5][6][7][8][9] Tetrahydrofuran (THF) is an excellent solvent to use when studying weakly acidic hydrides, their strong conjugate base forms, and weakly coordinated complexes, such as those containing the dihydrogen ligand. [1,[10][11][12][13] However, THF cannot be used as a solvent for very acidic compounds because it becomes protonated and undergoes ring-opening reactions.…”

Section: Introductionmentioning

confidence: 99%

An Acidity Scale of Tetrafluoroborate Salts of Phosphonium and Iron Hydride Compounds in [D₂]Dichloromethane

Li¹,

Lough²,

Morris³

2007

Chemistry A European J

View full text Add to dashboard Cite

Equilibrium constants (K) for reactions between acids and the conjugate base forms of a number of phosphonium salts, [HPR3][BF4], and iron hydrides, [Fe(CO)3H(PR3)2][BF4], in CD(2)Cl(2) have been determined by means of 31P and 1H NMR spectroscopy at 20 degrees C. The anchor compound chosen for pK(CD(2)Cl(2)) determinations was [HPCy3][BF4] with a pK(CD(2)Cl(2)) value of 9.7, as assigned by literature convention (Cy: cyclohexyl). A continuous scale of pK(CD(2)Cl(2)) values covering the range from 9.7 to -3 was created and correlated with the DeltaH values reported by Angelici and co-workers and literature pK(a) values. The pK(CD(2)Cl(2)) values for 15 other hydride or dihydrogen complexes of the iron group elements and of diethyl ether were also placed on this scale. The crystal structures of [Fe(CO)3H(PCy(2)Ph)2][BF4] and [Fe(CO)3(PCy(2)Ph)2] revealed that the trans-oriented, bulky, unsymmetrical phosphane ligands distort the equatorial plane of the complexes. The acidity of iron carbonyl hydrides is an important feature of the reactions of iron hydrogenase enzymes.

show abstract

“…Thus, the trans-PF 3 ligand exerts a high trans influence due to its strong π-acidity; in addition, it is also expected to stabilize the metal [12] and trans-[Ru(η 2 -H 2 )(CNH)(dppm) 2 ] 2ϩ (0.88 Å ) reported by Morris and coworkers. [13] Both of these compounds are unstable with respect to the loss of H 2 . Since 7 loses H 2 as noted earlier, we attempted to determine the equilibrium constant for the substitution of the bound H 2 with CH 3 CN as this could provide insight into the relative MϪH 2 bond strength for the complexes prepared in this study.…”

Section: H؊h Distances and The Stabilities Of The Dihydrogen Complexesmentioning

confidence: 99%

“…[14] In addition to this species, they also prepared a highly acidic dicationic dihydrogen complex, trans-[Ru(η 2 -H 2 )(CNH)(dppe) 2 ] 2ϩ that was found to be stable with respect to the loss of protons or H 2 under strongly acidic conditions (excess triflic acid). [13] A ligand that has similar π acidity to both CO and CNH is PF 3 . Dihydrogen complexes with the PF 3 ligand are limited to only one example, the rhenium complex fac-[Re (H 2 …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of the First Examples of Dicationic Dihydrogen Complexes of Iron and Ruthenium with the PF₃ Ligand

2004

View full text Add to dashboard Cite

New dicationic dihydrogen complexes of the type trans‐[M(η2‐H2)(PF3)(diphosphane)2]2+ [M = Ru, diphosphane = dppm (Ph2PCH2PPh2); M = Fe, Ru, diphosphane = dppe (Ph2PCH2CH2PPh2)] have been prepared from the precursor hydrides trans‐[M(H)(PF3)(diphosphane)2]+ upon reaction with HOTf. In the case of dppm, in addition to the trans‐dihydrogen complex cis‐[Ru(η2‐H2)(PF3)(dppm)2]2+ was also obtained in the protonation reaction. The intact nature of the H−H bond in these derivatives has been established using the spin−lattice relaxation time measurements (short T1 values) and the large JH,D coupling constant of the H−D isotopomers. The H−H bond lengths and the stabilities of the dihydrogen complexes are discussed in terms of the π‐acidity of the PF3 ligand and compared with other systems possessing trans CO and CNH ligands. The trans‐[Ru(η2‐H2)(PF3)(dppe)2]2+ complex was found to be remarkably stable with respect to the loss of bound H2 for a period of about 16 h. The H−D isotopomer of this complex exhibits small temperature variations in the JH,D coupling constant. The X‐ray crystal structure of trans‐[Ru(H)(PF3)(dppm)2][BF4] has been determined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

show abstract

Synthesis of the acidic dihydrogen complexes trans-[M(H2)(CN)L2]+ and trans-[M(H2)(CNH)L2]2+ where M = Fe, Ru, Os and L = dppm, dppe, dppp, depe, and dihydrogen substitution by the trifluoromethanesulfonate anion to give trans-[Ru(OTf )(CN)L2] or trans-[Ru(OTf )(CNH)L2]OTf †

Cited by 64 publications

References 47 publications

First Investigation of Non‐Classical Dihydrogen Bonding between an Early Transition‐Metal Hydride and Alcohols: IR, NMR, and DFT Approach

First Investigation of Non‐Classical Dihydrogen Bonding between an Early Transition‐Metal Hydride and Alcohols: IR, NMR, and DFT Approach

An Acidity Scale of Tetrafluoroborate Salts of Phosphonium and Iron Hydride Compounds in [D₂]Dichloromethane

Synthesis and Characterization of the First Examples of Dicationic Dihydrogen Complexes of Iron and Ruthenium with the PF₃ Ligand

Contact Info

Product

Resources

About

Synthesis of the acidic dihydrogen complexes trans-[M(H2)(CN)L2]+ and trans-[M(H2)(CNH)L2]2+ where M = Fe, Ru, Os and L = dppm, dppe, dppp, depe, and dihydrogen substitution by the trifluoromethanesulfonate anion to give trans-[Ru(OTf )(CN)L2] or trans-[Ru(OTf )(CNH)L2]OTf †

Cited by 64 publications

References 47 publications

First Investigation of Non‐Classical Dihydrogen Bonding between an Early Transition‐Metal Hydride and Alcohols: IR, NMR, and DFT Approach

First Investigation of Non‐Classical Dihydrogen Bonding between an Early Transition‐Metal Hydride and Alcohols: IR, NMR, and DFT Approach

An Acidity Scale of Tetrafluoroborate Salts of Phosphonium and Iron Hydride Compounds in [D2]Dichloromethane

Synthesis and Characterization of the First Examples of Dicationic Dihydrogen Complexes of Iron and Ruthenium with the PF3 Ligand

Contact Info

Product

Resources

About

An Acidity Scale of Tetrafluoroborate Salts of Phosphonium and Iron Hydride Compounds in [D₂]Dichloromethane

Synthesis and Characterization of the First Examples of Dicationic Dihydrogen Complexes of Iron and Ruthenium with the PF₃ Ligand