Comparing the acidity of hydride and .eta.2-dihydrogen complexes of transition metals

Jia, Guocheng; Morris, Robert H.

doi:10.1021/ic00329a003

Cited by 36 publications

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“…3 5.1 [14] 4.0 trans-[RuClA C H T U N G T R E N N U N G (dppe) 2 7.2 [14] 7.2 [14] [Ru ( 8.1 [15] 8.1 [Ru(Cp)(H) 2 8.4 [15,16] 8. 8.9 [17] 8.9…”

Section: Resultsmentioning

confidence: 99%

“…[14][15][16][17][18][19] The initial approach used was to find equilibria between these complexes and protonated phosphanes in which pK aq a values were reported to give a pseudoaqueous value by using 1 H and 31 P NMR spectroscopy. [15,16,18] A second approach was to construct a continuous set of overlapping equilibria to provide a more accurate ordering of acid strengths. For example, a ladder of acids with pK CD 2 Cl 2 values ranging from 9.7 to 7.0 was built and referenced arbitrarily to [HPCy 3 4 ] (Cy: cyclohexyl, pK a = 9.7) ( Table 1).…”

Section: Introductionmentioning

confidence: 99%

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

Li¹,

Lough²,

Morris³

2007

Chemistry A European J

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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.

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“…3 5.1 [14] 4.0 trans-[RuClA C H T U N G T R E N N U N G (dppe) 2 7.2 [14] 7.2 [14] [Ru ( 8.1 [15] 8.1 [Ru(Cp)(H) 2 8.4 [15,16] 8. 8.9 [17] 8.9…”

Section: Resultsmentioning

confidence: 99%

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

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“…Furthermore, although the pK a values of tautomeric classical and non-classical polyhydrides are usually rather similar, 34 non-classical hydride complexes are often kinetically more acidic than their classical counterparts. 17,34,35 Therefore, it seems quite likely that the proton transfer occurs via the [Mo]H(H 2 ) 21 complex and the involvement of this rapid interconversion is included in path (I) of Scheme 4. Furthermore, the electrochemical mechanistic study excludes that either [Mo]H 3 21 or [Mo]H(H 2 ) 21 coordinate MeCN in a rate determining step before being deprotonated.…”

Section: Addition Of Mecn To Classical Cpmo(dpe)hmentioning

confidence: 99%

Electrochemical and DFT studies of the oxidative decomposition of the trihydride complexes Cp*M(dppe)H3 (M = Mo, W) in acetonitrile

et al. 2006

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A detailed electrochemical study of the oxidative decomposition of the trihydride complexes Cp*M(dppe)H3 (M = Mo, W) in acetonitrile is presented. For the Mo complex, the decomposition occurs by four different pathways involving classical and n on classical tautomers, whereas only the classical form is accessible for the W derivative. Each of the decomposition pathways has been quantitatively assessed by analyses of the linear sweep voltammograms. In addition to the previously established ( J. Am.

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“…There have been other reports in the literature of the formation of dihydrogen complexes upon protonation of the hydrides with both strong and weak acids. [29,30] The fact that protonation of our hydride complexes failed with all acids except HOTf, and that the complete conversion of the hydrides to the corresponding η 2 -H 2 derivatives requires large excesses of the acid (HOTf), indicates that our dihydrogen complexes are extremely strong acids, being roughly similar to HOTf. [31] It is intriguing to note that 7 was found to be stable at room temperature under H 2 atmosphere for about 16 h after which time it begins to decompose.…”

Section: Protonation Reaction Of Trans-[ru(h)(pf 3 )(Dppe) 2 ][Bf 4 ]mentioning

confidence: 99%

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

2004

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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)

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Comparing the acidity of hydride and .eta.2-dihydrogen complexes of transition metals

Cited by 36 publications

References 0 publications

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

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

Electrochemical and DFT studies of the oxidative decomposition of the trihydride complexes Cp*M(dppe)H3 (M = Mo, W) in acetonitrile

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

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Comparing the acidity of hydride and .eta.2-dihydrogen complexes of transition metals

Cited by 36 publications

References 0 publications

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

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

Electrochemical and DFT studies of the oxidative decomposition of the trihydride complexes Cp*M(dppe)H3 (M = Mo, W) in acetonitrile

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

Contact Info

Product

Resources

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

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