A DFT‐based computational study is carried out to delve into the interplay between hyperconjugation and rehybridization effects underlying the formation of blue‐ or red‐shifting H‐bonds (HBs) in 1:1 complexes of cyclic ethers (HB acceptor) of varying ring‐size with haloforms, CHF3 and CHCl3 (HB donor). The calculations reveal that with decreasing angular strain (increasing ring‐size) of the cyclic ethers, the extent of blue‐shift increases for 1:1 complexes with CHF3, while a reverse sequence is observed with CHCl3, eventually leading to a red‐shifting HB in the oxepane:CHCl3 complex. It is noted that the trend in the shift of C‐H stretching fundamental is not mirrored by the C‐H bond length or interaction energies for both the systems studied, that is, the low sensitivity of the changes on the strain on the O‐atom of HB acceptor (cyclic ethers) is to be emphasized.

中文翻译：

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环醚与卤仿的蓝移和红移 C-H×××O 氢键：环尺寸的影响以及与本特规则的一致性

基于 DFT 的计算研究旨在深入研究不同环的 1:1 环醚（HB 受体）复合物中蓝移或红移氢键 (HBs) 形成的超共轭和再杂化效应之间的相互作用‐卤仿、CHF3 和 CHCl3（HB 供体）的尺寸。计算表明，随着环醚角应变的减小（环尺寸的增加），与 CHF3 的 1:1 配合物的蓝移程度增加，而用 CHCl3 观察到相反的顺序，最终导致红移氧杂环庚烷：CHCl3 络合物中的 HB。值得注意的是，C-H 拉伸基本位移的趋势并未通过所研究的两个系统的 C-H 键长或相互作用能反映出来，即 O- 应变变化的敏感性较低。需要强调的是HB受体（环醚）的原子。