Controlling the preferred nitrogen site in 1,2,3-triazine to bind with stannylenes

In the present quantum chemical study, the preferential σ -complexation pattern was established for a set of 10 model stannylenes (SnX 2 ) attached through a Sn ← N bond with 1,2,3-triazine ligand in a 1:1 fashion. Two non-equivalent σ -donor N -atoms in the ring of 1,2,3-triazine were considered as the binding sites for the electron-deficient metal center of SnX 2. Despite the higher nucleophilic character of the N atom at position 2 in the 1,2,3-triazine ring (N2), the N1 site turned out to be the preferred binding site for SnF 2, SnCl 2, SnI 2, Sn(CH 3 )Cl and Sn(NH 2 ) 2. Both binding sites led to similar energetic stability of σ -complexes with such stannylenes as Sn(C 2 H 5 ) 2 and cyclic SnC 4 H 8. Finally, Sn(SiH 3 ) 2 presented a slight preference for binding with the N2 site. This picture of σ -complexation was elucidated using both orbital-space and real-space approaches to the analysis of interactions occurring in molecular systems. The orbital-space perspective revealed that the electrostatic- and orbital-based factors act in accord for the five aforementioned stannylenes bound with the N1 site, hence the preference of this site. The real-space perspective indicated that stabilizing interactions between the X groups of SnX 2 and the ligand occur for the σ -complexation involving the N1 site but not necessarily for the Sn ← N2 σ -complexation.