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摘要
Ab initio calculations have been performed for the complexes of formamidine (FA) with TH3F (T=C, Si, Ge, and Sn) as well as the complexes of FA derivatives including CH3, NH2, OH, OCH3, CH2CH3, CH2CH2CH3, CH(CH3)(2), CF3, and F with SiH3F. 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 sigma-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 SiH3F with an interaction energy of approximate to 60kJ/mol. Four electron-donating groups give rise to the opposite effect on the strength of the tetrel bond: a weakening effect for OH and OCH3 but an enhancement for CH3 and NH2; the largest interaction energy occurs in CH3-(Z)-FA-SiH3F, amounting to a magnitude of 80kJ/mol. Two electron-withdrawing groups have a larger weakening effect than OH and OCH3. The effect of the larger alkyl group is dependent on the type of complex. The weak complexes of CH3F are driven by electrostatic and dispersion interactions, while the strong complexes of TH3F (T=Si, Ge, and Sn) are dominated by electrostatic and polarization interactions, as well as orbital interactions.
- 出版日期2018-3-14
- 单位烟台大学
