Hydride transfer from (η5-C5Me5)(CO)2MH (M = Fe, Ru, Os) to trityl cation: Different products from different metals and the kinetics of hydride transfer

Tan Yun Cheng, R. Morris Bullock

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72 Citations (Scopus)

Abstract

Reactions of the metal hydride complexes Cp*(CO)2MH (M = Fe, Ru, Os) with Ph3C+BF4 - in CH2C12 were studied. Hydride transfer from Cp*(CO)2FeH to Ph3C+BF4 - gives Cp*(CO)2FeFBF3. Hydride transfer from the ruthenium hydride Cp*(CO)2RuH to Ph3C+ BF4 - produces the bridging hydride complex {[Cp*(CO)2Ru]2(μ-H)}+BF4 -, indicating that Cp*(CO)2RuH exhibits significant nucleophilicity in addition to hydridic reactivity of the Ru-H bond. The osmium hydride Cp*(CO)2OsH reacts with Ph3C+BF4 - in CH2C12 to give a mixture of Cp*(CO)2OsFBF3 and [Cp*(CO)2Os(ClCH2Cl)]+BF4 -. The kinetics of these hydride transfer reactions were monitored by stopped-flow methods, leading to the second-order rate law -d[Ph3C+ BF4 - ]/dt = k[Ph3C+BF4 -] [MH]. The temperature dependence of the rate constants was determined for the iron hydride, the osmium hydride, and the osmium deuteride Cp*(CO)2OsD. Activation parameters for hydride transfer from Cp*(CO)2FeH are ΔH = 2.6 ± 0.1 kcal mol-1 and ΔS = -22.1 ± 0.4 cal K-1 mol-1; for Cp*(CO)2OsH the activation parameters are ΔH = 4.9 ± 0.1 kcal mol-1 and ΔS = -16.8 ± 0.5 cal K-1 mol-1. A kinetic isotope effect (kH/kD = 1.6 at 0 °C) was found for the reaction of Cp*(CO)2OsD. The order of kinetic hydricity is HRu > HFe > HOs. Second-order rate constants (extrapolated to 25 °C from data collected at lower temperatures) are k = 3.2 ± 105 M-1 s-1 for Cp*(CO)2OsH and k = 1.1 × 106 M-1 s-1 for Cp*(CO)2FeH; for Cp*(CO)2RuH, k > 5 × 106 M-1 s -1 is estimated at 25 °C. Rate constants were also determined for hydride transfer to Ph2(p-MeOC6H4)C+ at 25 °C: k = 1.5 × 105 M-1 s-1 for Cp*(CO)2RuH, k = 4.1 × 104 M-1 s-1 for Cp*(CO)2FeH, and k = 3.2 × 103 M-1 s-1 for Cp*(CO)2OsH.

Original languageEnglish
Pages (from-to)2325-2331
Number of pages7
JournalOrganometallics
Volume21
Issue number11
DOIs
Publication statusPublished - May 27 2002

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Carbon Monoxide
Hydrides
hydrides
Cations
Metals
cations
Kinetics
kinetics
products
metals
osmium
Osmium
activation
deuterides
Rate constants
metal hydrides
Hydrogen
isotope effect
ruthenium
Chemical activation

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

Cite this

@article{f3ca7ed1b60746b78bf0d4bea2150809,
title = "Hydride transfer from (η5-C5Me5)(CO)2MH (M = Fe, Ru, Os) to trityl cation: Different products from different metals and the kinetics of hydride transfer",
abstract = "Reactions of the metal hydride complexes Cp*(CO)2MH (M = Fe, Ru, Os) with Ph3C+BF4 - in CH2C12 were studied. Hydride transfer from Cp*(CO)2FeH to Ph3C+BF4 - gives Cp*(CO)2FeFBF3. Hydride transfer from the ruthenium hydride Cp*(CO)2RuH to Ph3C+ BF4 - produces the bridging hydride complex {[Cp*(CO)2Ru]2(μ-H)}+BF4 -, indicating that Cp*(CO)2RuH exhibits significant nucleophilicity in addition to hydridic reactivity of the Ru-H bond. The osmium hydride Cp*(CO)2OsH reacts with Ph3C+BF4 - in CH2C12 to give a mixture of Cp*(CO)2OsFBF3 and [Cp*(CO)2Os(ClCH2Cl)]+BF4 -. The kinetics of these hydride transfer reactions were monitored by stopped-flow methods, leading to the second-order rate law -d[Ph3C+ BF4 - ]/dt = k[Ph3C+BF4 -] [MH]. The temperature dependence of the rate constants was determined for the iron hydride, the osmium hydride, and the osmium deuteride Cp*(CO)2OsD. Activation parameters for hydride transfer from Cp*(CO)2FeH are ΔH‡ = 2.6 ± 0.1 kcal mol-1 and ΔS‡ = -22.1 ± 0.4 cal K-1 mol-1; for Cp*(CO)2OsH the activation parameters are ΔH‡ = 4.9 ± 0.1 kcal mol-1 and ΔS‡ = -16.8 ± 0.5 cal K-1 mol-1. A kinetic isotope effect (kH/kD = 1.6 at 0 °C) was found for the reaction of Cp*(CO)2OsD. The order of kinetic hydricity is HRu > HFe > HOs. Second-order rate constants (extrapolated to 25 °C from data collected at lower temperatures) are k = 3.2 ± 105 M-1 s-1 for Cp*(CO)2OsH and k = 1.1 × 106 M-1 s-1 for Cp*(CO)2FeH; for Cp*(CO)2RuH, k > 5 × 106 M-1 s -1 is estimated at 25 °C. Rate constants were also determined for hydride transfer to Ph2(p-MeOC6H4)C+ at 25 °C: k = 1.5 × 105 M-1 s-1 for Cp*(CO)2RuH, k = 4.1 × 104 M-1 s-1 for Cp*(CO)2FeH, and k = 3.2 × 103 M-1 s-1 for Cp*(CO)2OsH.",
author = "Cheng, {Tan Yun} and Bullock, {R. Morris}",
year = "2002",
month = "5",
day = "27",
doi = "10.1021/om020012o",
language = "English",
volume = "21",
pages = "2325--2331",
journal = "Organometallics",
issn = "0276-7333",
publisher = "American Chemical Society",
number = "11",

}

TY - JOUR

T1 - Hydride transfer from (η5-C5Me5)(CO)2MH (M = Fe, Ru, Os) to trityl cation

T2 - Different products from different metals and the kinetics of hydride transfer

AU - Cheng, Tan Yun

AU - Bullock, R. Morris

PY - 2002/5/27

Y1 - 2002/5/27

N2 - Reactions of the metal hydride complexes Cp*(CO)2MH (M = Fe, Ru, Os) with Ph3C+BF4 - in CH2C12 were studied. Hydride transfer from Cp*(CO)2FeH to Ph3C+BF4 - gives Cp*(CO)2FeFBF3. Hydride transfer from the ruthenium hydride Cp*(CO)2RuH to Ph3C+ BF4 - produces the bridging hydride complex {[Cp*(CO)2Ru]2(μ-H)}+BF4 -, indicating that Cp*(CO)2RuH exhibits significant nucleophilicity in addition to hydridic reactivity of the Ru-H bond. The osmium hydride Cp*(CO)2OsH reacts with Ph3C+BF4 - in CH2C12 to give a mixture of Cp*(CO)2OsFBF3 and [Cp*(CO)2Os(ClCH2Cl)]+BF4 -. The kinetics of these hydride transfer reactions were monitored by stopped-flow methods, leading to the second-order rate law -d[Ph3C+ BF4 - ]/dt = k[Ph3C+BF4 -] [MH]. The temperature dependence of the rate constants was determined for the iron hydride, the osmium hydride, and the osmium deuteride Cp*(CO)2OsD. Activation parameters for hydride transfer from Cp*(CO)2FeH are ΔH‡ = 2.6 ± 0.1 kcal mol-1 and ΔS‡ = -22.1 ± 0.4 cal K-1 mol-1; for Cp*(CO)2OsH the activation parameters are ΔH‡ = 4.9 ± 0.1 kcal mol-1 and ΔS‡ = -16.8 ± 0.5 cal K-1 mol-1. A kinetic isotope effect (kH/kD = 1.6 at 0 °C) was found for the reaction of Cp*(CO)2OsD. The order of kinetic hydricity is HRu > HFe > HOs. Second-order rate constants (extrapolated to 25 °C from data collected at lower temperatures) are k = 3.2 ± 105 M-1 s-1 for Cp*(CO)2OsH and k = 1.1 × 106 M-1 s-1 for Cp*(CO)2FeH; for Cp*(CO)2RuH, k > 5 × 106 M-1 s -1 is estimated at 25 °C. Rate constants were also determined for hydride transfer to Ph2(p-MeOC6H4)C+ at 25 °C: k = 1.5 × 105 M-1 s-1 for Cp*(CO)2RuH, k = 4.1 × 104 M-1 s-1 for Cp*(CO)2FeH, and k = 3.2 × 103 M-1 s-1 for Cp*(CO)2OsH.

AB - Reactions of the metal hydride complexes Cp*(CO)2MH (M = Fe, Ru, Os) with Ph3C+BF4 - in CH2C12 were studied. Hydride transfer from Cp*(CO)2FeH to Ph3C+BF4 - gives Cp*(CO)2FeFBF3. Hydride transfer from the ruthenium hydride Cp*(CO)2RuH to Ph3C+ BF4 - produces the bridging hydride complex {[Cp*(CO)2Ru]2(μ-H)}+BF4 -, indicating that Cp*(CO)2RuH exhibits significant nucleophilicity in addition to hydridic reactivity of the Ru-H bond. The osmium hydride Cp*(CO)2OsH reacts with Ph3C+BF4 - in CH2C12 to give a mixture of Cp*(CO)2OsFBF3 and [Cp*(CO)2Os(ClCH2Cl)]+BF4 -. The kinetics of these hydride transfer reactions were monitored by stopped-flow methods, leading to the second-order rate law -d[Ph3C+ BF4 - ]/dt = k[Ph3C+BF4 -] [MH]. The temperature dependence of the rate constants was determined for the iron hydride, the osmium hydride, and the osmium deuteride Cp*(CO)2OsD. Activation parameters for hydride transfer from Cp*(CO)2FeH are ΔH‡ = 2.6 ± 0.1 kcal mol-1 and ΔS‡ = -22.1 ± 0.4 cal K-1 mol-1; for Cp*(CO)2OsH the activation parameters are ΔH‡ = 4.9 ± 0.1 kcal mol-1 and ΔS‡ = -16.8 ± 0.5 cal K-1 mol-1. A kinetic isotope effect (kH/kD = 1.6 at 0 °C) was found for the reaction of Cp*(CO)2OsD. The order of kinetic hydricity is HRu > HFe > HOs. Second-order rate constants (extrapolated to 25 °C from data collected at lower temperatures) are k = 3.2 ± 105 M-1 s-1 for Cp*(CO)2OsH and k = 1.1 × 106 M-1 s-1 for Cp*(CO)2FeH; for Cp*(CO)2RuH, k > 5 × 106 M-1 s -1 is estimated at 25 °C. Rate constants were also determined for hydride transfer to Ph2(p-MeOC6H4)C+ at 25 °C: k = 1.5 × 105 M-1 s-1 for Cp*(CO)2RuH, k = 4.1 × 104 M-1 s-1 for Cp*(CO)2FeH, and k = 3.2 × 103 M-1 s-1 for Cp*(CO)2OsH.

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DO - 10.1021/om020012o

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