Influence of alkali substituents on the strength, properties, and nature of tetrel bond between TH 3 F and pyridine
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ORIGINAL PAPER
Influence of alkali substituents on the strength, properties, and nature of tetrel bond between TH3F and pyridine Xiulin An 1
&
Jianqu Han 2
Received: 27 May 2020 / Accepted: 3 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Ab initio calculations have been performed for the complexes of TH3F (T=C, Si, and Ge) with pyridine and its alkali derivatives to study the influence of an alkali substituent on the strength, properties, and nature of tetrel bond. The introduction of an alkali atom into the electron donor has a prominent enhancing effect on the strength of tetrel bond, which depends on the T atom as well as the alkali atom and its substitution position. The enhancing effect becomes larger in the C < Ge < Si, Li < Na < K, and para- < meta- < ortho- patterns. The interaction energy varies in a wide range from 2 to 40 kcal/mol. Both electrostatic and polarization including charge transfer are responsible for the enhancing effect of an alkali atom. The formation of a tetrel bond results in an elongation of F-T bond and a red shift of F-T stretch vibration, which is big enough to be detected with infrared spectroscopy. Electrostatic interaction is dominant in all complexes, while polarization is smaller or larger than dispersion in the complexes of CH3F or TH3F(T=Si and Ge). Keywords Tetrel bond . Alkali substituents . AIM . NBO
Introduction Tetrel bond (TB) is an attractive interaction between the group 14 element (tetrel) and an electron donor [1]. TB can be taken as a linker in crystal materials like hydrogen and halogen bonds [1]. In constructing these crystal materials, TB often coexists with other types of interactions, displaying cooperativity [2–4]. TB plays a stabilizing role in the preliminary stage of the SN2 reaction [5] as well as in its posterior stage [6]. More importantly, TB can stabilize the structures of some proteins and regulate their biological functions [7–9]. Because of these applications, lots of theoretical studies have been performed for the TBs [10–15]. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00894-020-04499-x) contains supplementary material, which is available to authorized users. * Xiulin An [email protected] 1
College of Life Science, Yantai University, Yantai 264005, People’s Republic of China
2
The Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Yantai University, Yantai 264005, China
People firstly focus on the mechanism of TB formation [5, 16, 17]. By means of analyzing electrostatic potentials of tetrel donor molecules, it is found that a positive electrostatic potential centers on the tetrel atom. This electrostatic potential locates at the T-R bond end in the sp3-hybridized tetrel donor molecule [16] or is vertical to the molecular plane in the sp2hybridized tetrel donor molecule [17]. The corresponding regions are called σ-hole and π-hole. Such hole means that TB is dominated by an electrostatic interaction in
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