Abstract
Direct measurement of the enthalpy of decomposition of HCr(CO)3C5H5 to [Cr(CO)3C5H5]2 and H2 was made by differential scanning calorimetry. The heat of hydrogenation of 1,3-cyclohexadiene by HM(CO)3C5H5 for M = Cr, Mo, and W was measured by solution calorimetry. The enthalpies of iodination of [M(CO)3C5H5]2 and HM(CO)3C5H5 were measured for M = Mo and W. These data have been used to calculate the heats of hydrogenation for each of the metal-metal bonded dimers, [M(CO)3C5H5]2 (M = Cr, Mo, and W). C5H5(CO)3M-M(CO)3C5H5(s) + H2(g) → 2HM(CO)3C5H5(s). Addition of hydrogen has been found to be exothermic for M = Cr, W (-3.3 kcal/mol and -1.5 kcal/mole, respectively) but endothermic for M = Mo (+6.3 kcal/mol). These results are consistent with the trend of increasing MH bond strengths upon descending Group VI. Addition of H2 to [Cr(CO)3C5H5]2 is favored by the unusually weak chromium-chromium bond.
| Original language | English |
|---|---|
| Pages (from-to) | 215-224 |
| Number of pages | 10 |
| Journal | Journal of Organometallic Chemistry |
| Volume | 282 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 5 1985 |
Fingerprint
ASJC Scopus subject areas
- Biochemistry
- Chemical Engineering (miscellaneous)
- Inorganic Chemistry
- Organic Chemistry
- Physical and Theoretical Chemistry
- Materials Science (miscellaneous)
- Materials Chemistry
Cite this
The heats of hydrogenation of the metal-metal bonded complexes [M(CO)3C5H5]2 (M = Cr, Mo, W). / Landrum, John T.; Hoff, Carl.
In: Journal of Organometallic Chemistry, Vol. 282, No. 2, 05.03.1985, p. 215-224.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The heats of hydrogenation of the metal-metal bonded complexes [M(CO)3C5H5]2 (M = Cr, Mo, W)
AU - Landrum, John T.
AU - Hoff, Carl
PY - 1985/3/5
Y1 - 1985/3/5
N2 - Direct measurement of the enthalpy of decomposition of HCr(CO)3C5H5 to [Cr(CO)3C5H5]2 and H2 was made by differential scanning calorimetry. The heat of hydrogenation of 1,3-cyclohexadiene by HM(CO)3C5H5 for M = Cr, Mo, and W was measured by solution calorimetry. The enthalpies of iodination of [M(CO)3C5H5]2 and HM(CO)3C5H5 were measured for M = Mo and W. These data have been used to calculate the heats of hydrogenation for each of the metal-metal bonded dimers, [M(CO)3C5H5]2 (M = Cr, Mo, and W). C5H5(CO)3M-M(CO)3C5H5(s) + H2(g) → 2HM(CO)3C5H5(s). Addition of hydrogen has been found to be exothermic for M = Cr, W (-3.3 kcal/mol and -1.5 kcal/mole, respectively) but endothermic for M = Mo (+6.3 kcal/mol). These results are consistent with the trend of increasing MH bond strengths upon descending Group VI. Addition of H2 to [Cr(CO)3C5H5]2 is favored by the unusually weak chromium-chromium bond.
AB - Direct measurement of the enthalpy of decomposition of HCr(CO)3C5H5 to [Cr(CO)3C5H5]2 and H2 was made by differential scanning calorimetry. The heat of hydrogenation of 1,3-cyclohexadiene by HM(CO)3C5H5 for M = Cr, Mo, and W was measured by solution calorimetry. The enthalpies of iodination of [M(CO)3C5H5]2 and HM(CO)3C5H5 were measured for M = Mo and W. These data have been used to calculate the heats of hydrogenation for each of the metal-metal bonded dimers, [M(CO)3C5H5]2 (M = Cr, Mo, and W). C5H5(CO)3M-M(CO)3C5H5(s) + H2(g) → 2HM(CO)3C5H5(s). Addition of hydrogen has been found to be exothermic for M = Cr, W (-3.3 kcal/mol and -1.5 kcal/mole, respectively) but endothermic for M = Mo (+6.3 kcal/mol). These results are consistent with the trend of increasing MH bond strengths upon descending Group VI. Addition of H2 to [Cr(CO)3C5H5]2 is favored by the unusually weak chromium-chromium bond.
UR - http://www.scopus.com/inward/record.url?scp=0039191216&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0039191216&partnerID=8YFLogxK
U2 - 10.1016/0022-328X(85)87171-0
DO - 10.1016/0022-328X(85)87171-0
M3 - Article
AN - SCOPUS:0039191216
VL - 282
SP - 215
EP - 224
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
SN - 0022-328X
IS - 2
ER -