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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >G2 Theory and Experiment in Concert: Enthalphy of Formation of CH_3O-C=O~+ and Its Isomers Revisited
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G2 Theory and Experiment in Concert: Enthalphy of Formation of CH_3O-C=O~+ and Its Isomers Revisited

机译：G2理论与实验相一致：CH_ 3 O-C = O〜+及其异构体的形成焓

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摘要

Ab initio molecular orbital calculations at the Gaussian-2 level of theory on a set of isodesmic, atomization, and substitution type reactions have been used to deduced the enthalpy of formation of the methoxy carbonyl ion as #DELTA#H_F~(298) (CH_3O-C=O~+) = 130 +- 2 kcal/mol. From the G2 computed ionization energy (IE_a = 7.32 eV) and #DELTA#H_f~(298)(-40 kcal/mol) of the parent radical CH_3O-C=O, we arrive at 129 kcal/mol for its ionic counterpart. Combining these theoretical findings with a reevaluation of existing experimental data (appearance energy measurements) yields 129 +- 2 kcal/mol as our recommended value for #DELTA#H_F~(298) (CH_3O-C=O~+), a large upward revision of the current literature value of 120 kcal/mol. By use of the new value as the anchor point, G2 derived #DELTA#H_F~(298) values for the isomers H_2C-O-C(H)OH~+, HOCH_2-C=~+, ~+ CH_2-H...O=C=O, ~+CH(OH)-C(=O)H, ~+CH_2-O-C(=O)H, CH_2-O-C(H)-O~+, and ~+CH_2O-C-OH have been calculated as 147, 131, 157, 144, 144, 140, and 177 kcal/mol, respectively.
机译：在高斯2级理论上对一组等渗，原子化和取代型反应进行了从头算的分子轨道计算，以推导出形成＃DELTA＃H_F〜（298）（CH_3O）的甲氧基羰基离子的焓-C ＝ O〜+）＝ 130±2kcal / mol。从G2计算的母离子CH_3O-C = O的电离能（IE_a = 7.32 eV）和＃DELTA＃H_f〜（298）（-40 kcal / mol），我们得出其离子对应物为129 kcal / mol。将这些理论发现与对现有实验数据的重新评估（外观能量测量）相结合，得出的129 +-2 kcal / mol作为我们对＃DELTA＃H_F〜（298）（CH_3O-C = O〜+）的推荐值修订目前的文献值为120 kcal / mol。通过使用新值作为锚点，G2得出了异构体H_2C-OC（H）OH〜+，HOCH_2-C =〜+，〜+ CH_2-H ...的＃DELTA＃H_F〜（298）值... O = C = O，〜+ CH（OH）-C（= O）H，〜+ CH_2-OC（= O）H，CH_2-OC（H）-O〜+和〜+ CH_2O-C-OH分别计算为147、131、157、144、144、140和177 kcal / mol。

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