Thermodynamics for the hydrogenation of dimanganese decacarbonyl
Thermodynamics for the hydrogenation of dimanganese decacarbonyl
复制标题
十羰基二锰加氢的热力学
DOI：
10.1021/ic00031a021
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发表时间：
1992
影响因子：
4.6
通讯作者：
J. W. Rathke
中科院分区：
文献类型：
--
作者：
R. J. Klingler;J. W. Rathke
Mn{sub 2}(CO){sub 10}在超临界二氧化碳中氢化的平衡常数已在一氧化碳和氢气下、总系统压力为142-300 atm下通过原位{sup 55}Mn和{sup 1}H NMR光谱在165-220C的温度范围内测量。通过向体系中添加Co{sub 2}(CO){sub 8}，可以有效促进Mn{sub 2}(CO){sub 10}的氢化。添加1当量的Co{sub 2}(CO){sub 8}后，100℃下HMn(CO){sub 5}的生成速率提高了2个数量级。这种促进作用的强度已将温度范围扩大到 80°C，在该温度范围内可以确定 Mn{sub 2}(CO){sub 10} 氢化的平衡常数。发现在存在和不存在 Co{sub 2}(CO){sub 8} 促进剂的情况下 Mn{sub 2}(CO){sub 10} 氢化的 Van't Hoff 图产生了标准的焓和熵变化，这些变化符合平衡常数测量的统计误差限度内。对组合数据集的最终分析得出 Mn{sub 2}(CO){sub 10} 氢化的 {Delta}H{ Degree} = 8.7 {plus minus} 0.3 kcal/mol 和 {Delta}S{ Degree} = 8.5 {plus minus} 0.8 cal/(K{center dot}mol)。在混合金属体系内，异双金属二聚体 Mn(CO){sub 5}-Co(CO){sub 4} 在 {sup 55}Mn 和 {sup 59}Co NMR 谱中作为附加反应产物被观察到。从同核二聚体 Mn{sub 2}(CO){sub 10} 和 Co{sub 2}(CO){sub 8} 产生 2 当量 MnCo(CO){sub 9} 的再分配反应的热力学几乎是热中性的，表现出 {Delta}H{ Degree} = 0.8 {plus minus} 0.3 kcal/mol 和 {Delta}S{ Degree} = 0.7 {plus分别为减去} 0.8 cal/(K{center dot}mol)。« 更少
The equilibrium constant for the hydrogenation of Mn{sub 2}(CO){sub 10} in supercritical carbon dioxide has been measured under carbon monoxide and hydrogen at total system pressures of 142-300 atm by in situ {sup 55}Mn and {sup 1}H NMR spectroscopy over the temperature range 165-220C. The hydrogenation of Mn{sub 2}(CO){sub 10} is efficiently promoted by the addition of Co{sub 2}(CO){sub 8} to the system. The rate of HMn(CO){sub 5} production at 100C is increased by 2 orders of magnitude with the addition of 1 equiv of Co{sub 2}(CO){sub 8}. The magnitude of this promotional effect has extended the range of temperatures down to 80C over which it is feasible to determine the equilibrium constant for Mn{sub 2}(CO){sub 10} hydrogenation. Van't Hoff plots for the hydrogenation of Mn{sub 2}(CO){sub 10} in the presence and absence of the Co{sub 2}(CO){sub 8} promoter were found to yield standard enthalpy and entropy changes that agree to within the statistical error limit of the equilibrium constant measurements. The resultant analysis for the combined data set yields {Delta}H{degree} = 8.7 {plus minus} 0.3 kcal/mol and {Delta}S{degree} = 8.5 {plus minus} 0.8 cal/(K{center dot}mol) for the hydrogenation of Mn{sub 2}(CO){sub 10}. The heterobimetallic dimer Mn(CO){sub 5}-Co(CO){sub 4} ismore » observed as an additional reaction product in both the {sup 55}Mn and the {sup 59}Co NMR spectra, within the mixed-metal system. The thermodynamics for the redistribution reaction yielding 2 equiv of MnCo(CO){sub 9} from the homonuclear dimers, Mn{sub 2}(CO){sub 10} and Co{sub 2}(CO){sub 8} was found to be nearly thermal neutral exhibiting {Delta}H{degree} = 0.8 {plus minus} 0.3 kcal/mol and {Delta}S{degree} = 0.7 {plus minus} 0.8 cal/(K{center dot}mol), respectively.« less