Tuning the Competition between Hydrogen and Tetrel Bonds by a Magnesium Bond

Abstract

Abstract A computational study of the complexes formed by TF 3 OH (T=C, Si, Ge) with three nitrogen‐containing bases NCH, NH 3 , and imidazole (IM) is carried out at the MP2/aug‐cc‐pVTZ level. TF 3 OH can participate in two different types of noncovalent interactions: a hydrogen bond (HB) involving the hydroxyl proton and a tetrel bond (TB) with the tetel atom T. The strength of the HB is largely unaffected by the identity of T while the TB is enhanced as T grows larger. The HB is preferred over the TB for most systems, with the exception of GeF 3 OH with either NH 3 or IM. MgCl 2 engages in a Mg⋅⋅⋅O Magnesium bond (Mg‐bond) with the TF 3 OH O atom, which cooperatively enhances both the HB and TB. The HB strengthening is particularly large for the NH 3 or IM bases, and especially for CF 3 OH, but is slowly reduced as the T atom grows larger. The TB enhancement, on the other hand, behaves in the opposite fashion, accelerating for the larger T atoms. As a bottom line, the Mg‐bond generally reinforces and accentuates the preference for the HB or TB that is already present in the dimer. The Mg‐bond is also responsible for a proton transfer in the HB configurations with NH 3 and IM.