Neutron Diffraction and Spectroscopic Studies of Intramolecular Tetrel Bonds in Three Fluorinated Zinc Complexes: Significant Redshift in the sp 3 C–H Stretch Confirmed by Experiments and Theory

作者：Norman Lu, Gurumallappa Gurumallappa, Pin-Yu Liu, Ka Long Chan, Yucheng Huang, Yu‐Ching Lin, Yun-Ting Hsieh, Pan Zeng, Yashwanth Gowda, Meng‐Hsun Tsai, Eskedar Tessema, Huan‐Cheng Chang, Joseph S. Francisco · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.5c15040 · 被引用次数：3 · 研究领域：Inorganic Fluorides and Related Compounds、Crystallography and molecular interactions、Fluorine in Organic Chemistry

High Resolution Image Download MS PowerPoint Slide Three fluorinated Zn complexes were synthesized and characterized. Their single crystals were grown and studied via X-ray and neutron diffraction methods. These fluorinated metal complexes tend to form two special noncovalent interactions: an intramolecular tetrel bond (TB) and an intramolecular blueshifting hydrogen bond (HB). In 4FH-ZnCl 2 [2,6-(HCF 2 CF 2 CH 2 OCH 2 ) 2 -py-ZnCl 2 ], an intramolecular TB induces significant elongation of a C–H bond in a methylene group, H1A–C1–H1B, to 1.108(2) Å, whereas the intramolecular C1–H1A···F2 blueshifting HB shortens the C1–H1A bond to 1.092(1) Å. Thus, C1–H1B is longer than C1–H1A by 16(2) mÅ such that either one of the C1–H1 stretches becomes a methine-like stretch with a peak appearing at 3020 or 2688 cm –1 . A peak corresponding to a lengthened sp 3 C1–H1B bond is greatly redshifted and appears at 2688 cm –1 . When this 2688 cm –1 peak is compared with its other methylene C–H peak (3020 cm –1 ), their C–H vibrational stretches then differ by 332 cm –1, which is likely the largest ever sp 3 C–H bond stretching difference reported between two methylene C–H bonds. Additionally, two C–D bonds of deuterated 4FH-ZnCl 2, which has an intramolecular C···F TB that induces very different lengths of the two C–D bonds in a D–C–D group, become a local mode, as proven by Hooke’s law. Thus, Badge’s rule has been extended by using both neutron and spectroscopic studies.