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Abnormal Tetrel Bonds between Formamidine and TH 3 F: Substituent Effects
Author(s) -
Xu Huili,
Cheng Jianbo,
Yu Xuefang,
Li Qingzhong
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201800025
Subject(s) - substituent , chemistry , alkyl , crystallography , atom (system on chip) , stereochemistry , medicinal chemistry , organic chemistry , computer science , embedded system
Ab initio calculations have been performed for the complexes of formamidine (FA) with TH 3 F (T=C, Si, Ge, and Sn) as well as the complexes of FA derivatives including CH 3 , NH 2 , OH, OCH 3 , CH 2 CH 3 , CH 2 CH 2 CH 3 , CH(CH 3 ) 2 , CF 3 , and F with SiH 3 F. In general, each complex is stabilized by both a main tetrel bond and a secondary interaction. The stability of the complex increases in the order T=C < Ge < Si < Sn, inconsistent with the magnitude of the σ‐hole on the tetrel atom. The (Z)‐FA complex is more stable than the (E)‐FA analogue. The imino nitrogen atom of FA is a better tetrel acceptor than most nitrogenated bases; it shows a particularly strong affinity for SiH 3 F with an interaction energy of ∼60 kJ/mol. Four electron‐donating groups give rise to the opposite effect on the strength of the tetrel bond: a weakening effect for OH and OCH 3 but an enhancement for CH 3 and NH 2 ; the largest interaction energy occurs in CH 3 ‐(Z)‐FA‐SiH 3 F, amounting to a magnitude of 80 kJ/mol. Two electron‐withdrawing groups have a larger weakening effect than OH and OCH 3 . The effect of the larger alkyl group is dependent on the type of complex. The weak complexes of CH 3 F are driven by electrostatic and dispersion interactions, while the strong complexes of TH 3 F (T=Si, Ge, and Sn) are dominated by electrostatic and polarization interactions, as well as orbital interactions.