The standard enthalpies of hydrogenation of 29 unsaturated hydrocarbon compounds were calculated in the gas phase by M06-2X theory with the 6-31g(d) and cc-pVXZ, where X = DZ, TZ, QZ, as well as by complete basis set extrapolated level. Geometries of compounds were optimized at the M06-2X/6-31g(d) level. These M06-2X geometries were used in the M06-2X, and extrapolation calculations with cc-pVXZ basis sets. Comparison of calculation and experimental results shows that the mean absolute deviations between the calculated and experimental enthalpies of hydrogenation range from 25.1 to 5.1 kJ mol−1 at M06-2X calculations, and when using cc-pV(DT)Z extrapolated level, the mean absolute deviations have decreased to 2.7. The results of some calculations showed that the deviations from experimental values are located inside the “chemical accuracy” (±1 kcal mol−1≈±4.2 kJ mol−1). Very good linear correlations between experimental and calculated enthalpies of hydrogenation have been obtained at M06-2X/cc-pVTZ and cc-pV(DT)Z extrapolated levels (standard deviation = 3.2 and 3.4 kJ mol−1, respectively).

中文翻译：

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通过 M06-2X/CBS 外推水平在气相中计算烃的加氢焓

29种不饱和烃化合物在气相中的标准加氢焓是通过M06-2X理论用6-31g(d)和cc-pVXZ计算的，其中X = DZ、TZ、QZ，以及完全基组外推水平。在 M06-2X/6-31g(d) 水平优化化合物的几何结构。这些 M06-2X 几何形状用于 M06-2X，以及使用 cc-pVXZ 基组的外推计算。计算和实验结果的比较表明，在 M06-2X 计算中，计算和实验加氢焓的平均绝对偏差范围为 25.1 至 5.1 kJ mol-1，当使用 cc-pV(DT)Z 外推水平时，平均值绝对偏差已降至 2.7。一些计算的结果表明，与实验值的偏差位于“化学精度”范围内（±1 kcal mol-1≈±4.2 kJ mol-1）。在 M06-2X/cc-pVTZ 和 cc-pV(DT)Z 外推水平（标准偏差分别为 3.2 和 3.4 kJ mol-1）下，实验和计算的氢化焓之间获得了非常好的线性相关性。