Abstract
Enthalpies of reaction with sodium amalgam, sodium benzophenone ketyl, and metal carbonyl anions of organometallic complexes in THF solution have been measured. Relative to reduction with Na metal, the following enthalpies of reduction (kcal mol-1) are reported: benzophenone = -38.5, Cr(CO)2(PEt3)C5H5 = -54.3, Cr(CO)2(PPh3)C5H5 = -59.8, 1/2[Mo(CO)3C5Me5]2 = -59.9, 1/2[W(CO)3C5H5]2 = -61.7, 1/2[Mo(CO)3C5H5]2 = -63.5, Cr(CO)2(P(OMe)3)C5H5 = -64.4, 1/2[C5H5(CO)3Mo-Cr(CO)3C5H5] = -66.1, 1/2[Cr(CO)3C5H5]2 = -68.2, Cr(CO)3C5Me5 = -72.3, Cr(CO)3C5H5 = -75.6, 1/2Co2(CO)8 = -77.9. The value for the enthalpy of reduction of benzophenone is 14.5 kcal mol-1 more exothermic than recent literature data. The enthalpies of electron transfer and proton transfer between NaCr(CO)2C5H5 and other chromium radicals and hydrides have been measured and span about 20 kcal mol-1. These measurements are used in thermochemical cycles to calculate enthalpies of H atom transfer. The role of substituents in determining enthalpies of reaction relevant to electrochemical and pKa measurement enthalpies of reaction is discussed. The heat of hydrogenation of Mn2(CO)10 has been determined using calorimetrically determined enthalpies of H atom transfer. The heat of hydrogenation, +4 kcal mol-1 in THF, allows estimation of the MnH bond strength = 68 kcal mol-1.
| Original language | English |
|---|---|
| Pages (from-to) | 285-292 |
| Number of pages | 8 |
| Journal | Inorganica Chimica Acta |
| Volume | 227 |
| Issue number | 2 |
| DOIs | |
| State | Published - Dec 15 1994 |
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Keywords
- Calorimetry
- Electron transfer reactions
- Enthalpy
- Metal hydrides
- Metal-metal bond energies
- Proton transfer reactions
ASJC Scopus subject areas
- Biochemistry
- Inorganic Chemistry
- Physical and Theoretical Chemistry
- Materials Chemistry
Cite this
Direct solution calorimetric measurements of enthalpies of proton and electron transfer reactions for transition metal complexes. Thermochemical study of metal-hydride and metal-metal bond energies. / Kiss, Gabor; Nolan, Steven P.; Hoff, Carl.
In: Inorganica Chimica Acta, Vol. 227, No. 2, 15.12.1994, p. 285-292.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Direct solution calorimetric measurements of enthalpies of proton and electron transfer reactions for transition metal complexes. Thermochemical study of metal-hydride and metal-metal bond energies
AU - Kiss, Gabor
AU - Nolan, Steven P.
AU - Hoff, Carl
PY - 1994/12/15
Y1 - 1994/12/15
N2 - Enthalpies of reaction with sodium amalgam, sodium benzophenone ketyl, and metal carbonyl anions of organometallic complexes in THF solution have been measured. Relative to reduction with Na metal, the following enthalpies of reduction (kcal mol-1) are reported: benzophenone = -38.5, Cr(CO)2(PEt3)C5H5 = -54.3, Cr(CO)2(PPh3)C5H5 = -59.8, 1/2[Mo(CO)3C5Me5]2 = -59.9, 1/2[W(CO)3C5H5]2 = -61.7, 1/2[Mo(CO)3C5H5]2 = -63.5, Cr(CO)2(P(OMe)3)C5H5 = -64.4, 1/2[C5H5(CO)3Mo-Cr(CO)3C5H5] = -66.1, 1/2[Cr(CO)3C5H5]2 = -68.2, Cr(CO)3C5Me5 = -72.3, Cr(CO)3C5H5 = -75.6, 1/2Co2(CO)8 = -77.9. The value for the enthalpy of reduction of benzophenone is 14.5 kcal mol-1 more exothermic than recent literature data. The enthalpies of electron transfer and proton transfer between NaCr(CO)2C5H5 and other chromium radicals and hydrides have been measured and span about 20 kcal mol-1. These measurements are used in thermochemical cycles to calculate enthalpies of H atom transfer. The role of substituents in determining enthalpies of reaction relevant to electrochemical and pKa measurement enthalpies of reaction is discussed. The heat of hydrogenation of Mn2(CO)10 has been determined using calorimetrically determined enthalpies of H atom transfer. The heat of hydrogenation, +4 kcal mol-1 in THF, allows estimation of the MnH bond strength = 68 kcal mol-1.
AB - Enthalpies of reaction with sodium amalgam, sodium benzophenone ketyl, and metal carbonyl anions of organometallic complexes in THF solution have been measured. Relative to reduction with Na metal, the following enthalpies of reduction (kcal mol-1) are reported: benzophenone = -38.5, Cr(CO)2(PEt3)C5H5 = -54.3, Cr(CO)2(PPh3)C5H5 = -59.8, 1/2[Mo(CO)3C5Me5]2 = -59.9, 1/2[W(CO)3C5H5]2 = -61.7, 1/2[Mo(CO)3C5H5]2 = -63.5, Cr(CO)2(P(OMe)3)C5H5 = -64.4, 1/2[C5H5(CO)3Mo-Cr(CO)3C5H5] = -66.1, 1/2[Cr(CO)3C5H5]2 = -68.2, Cr(CO)3C5Me5 = -72.3, Cr(CO)3C5H5 = -75.6, 1/2Co2(CO)8 = -77.9. The value for the enthalpy of reduction of benzophenone is 14.5 kcal mol-1 more exothermic than recent literature data. The enthalpies of electron transfer and proton transfer between NaCr(CO)2C5H5 and other chromium radicals and hydrides have been measured and span about 20 kcal mol-1. These measurements are used in thermochemical cycles to calculate enthalpies of H atom transfer. The role of substituents in determining enthalpies of reaction relevant to electrochemical and pKa measurement enthalpies of reaction is discussed. The heat of hydrogenation of Mn2(CO)10 has been determined using calorimetrically determined enthalpies of H atom transfer. The heat of hydrogenation, +4 kcal mol-1 in THF, allows estimation of the MnH bond strength = 68 kcal mol-1.
KW - Calorimetry
KW - Electron transfer reactions
KW - Enthalpy
KW - Metal hydrides
KW - Metal-metal bond energies
KW - Proton transfer reactions
UR - http://www.scopus.com/inward/record.url?scp=0006345267&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0006345267&partnerID=8YFLogxK
U2 - 10.1016/0020-1693(94)04218-7
DO - 10.1016/0020-1693(94)04218-7
M3 - Article
AN - SCOPUS:0006345267
VL - 227
SP - 285
EP - 292
JO - Inorganica Chimica Acta
JF - Inorganica Chimica Acta
SN - 0020-1693
IS - 2
ER -