We suggest a scale of dispersion energy donors (DEDs) that allows for direct comparisons with steric effects. This scale is based on the classic A-values and allows groups to reorient to minimize strain, thereby providing an advantage over raw group polarizabilities. The A-value can no longer be considered purely a steric factor. Even for groups that do not participate in charge transfer or electrostatic interactions, the A-value includes Pauli repulsion (steric hindrance) and attractive London dispersion (LD) interactions. Although the common assumption is that, at the distances found in monosubstituted cyclohexanes, steric demands are the key factors influencing conformer preferences, we show in this computational study that there is a non-negligible LD part. We use this system to build a DED scale and a complementary steric scale. These scales are quantitatively comparable, as they are based on the same system, and allow for comparison of the two competing interactions in experimentally relevant settings. In addition, we show that LD interactions can be used to explain puzzling data regarding relative group sizes.

中文翻译：

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伦敦分散有助于改进空间 A 值：分散能量供体量表

我们建议了一个允许与空间效应直接比较的色散能量供体 (DED) 规模。该量表基于经典的 A 值，允许组重新定向以最小化应变，从而提供优于原始组极化率的优势。A 值不能再被视为纯粹的空间因素。即使对于不参与电荷转移或静电相互作用的基团，A 值也包括泡利斥力（空间位阻）和有吸引力的伦敦色散 (LD) 相互作用。尽管普遍的假设是，在单取代环己烷中发现的距离，空间需求是影响构象偏好的关键因素，但我们在这项计算研究中表明存在不可忽略的 LD 部分。我们使用这个系统来构建一个 DED 量表和一个互补的空间量表。这些量表在数量上具有可比性，因为它们基于相同的系统，并允许在实验相关设置中比较两种相互竞争的相互作用。此外，我们表明 LD 交互可用于解释有关相对组大小的令人费解的数据。