N → Sn coordination in the complexes of tin halides with pyridine: A comparison between Sn(II) and Sn(IV)

Abstract

The experimentally well‐known complexation of tin(II) and tin(IV) halides with pyridine (py) leads to structures showing N → Sn coordination. In the present work, the complexes SnXn·mpy (where X = F, Cl, Br, I; n = 2, 4; m = 1, 2) possessing this kind of coordination were studied using a computational quantum chemical approach. Various aspects in the theoretical picture of these complexes were examined to find similarities and differences in their N → Sn coordination. The aspects included, among others, the physical nature of intermolecular interactions, and their role in establishing the structure and energetic stabilization of the complexes. In this context, the effect of tin valency was inspected in great detail. As proven by several theoretical methods, a largely ionic character with a certain covalent component can be attributed to the studied N → Sn coordination, irrespective of tin valency. All complexes are destabilized by py‐py and three‐body interactions, but the Sn(II) complexes experience it to a greater extent. Marked differences are observed in the structural behavior of N → Sn and SnXn during complex formation. This affects the energetics of complexation and, in consequence, the penta‐coordinated Sn(IV) center shows a higher propensity to expand its coordination number, compared with the tri‐coordinated Sn(II) center. The present study supplements the experimental characterization of SnXn·mpy and, in general, it sheds light on the coordination of heteroaromatic nitrogen to tin. The survey of the Cambridge Structural Database revealed that such coordination occurred in a number of crystal structures.

Tuning the metal–ligand bond in theσ‐complexes of stannylenes and azabenzenes

“…The importance of electrostatics in 1a-l is in agreement with further theoretical studies on the nature of stannylene-N-donor ligand interactions. 40,44,45 The SAPT(DFT) method predicts somewhat larger ratios of electrostatic components in 1b-c in comparison to the results obtained by LMO-EDA. 45 The exchange repulsion in 1a-l cannot be compensated solely by E elst , and the addition of E ind to the E elst and E exch components is essential to stabilize 1a-l.…”

“…40,44,45 The SAPT(DFT) method predicts somewhat larger ratios of electrostatic components in 1b-c in comparison to the results obtained by LMO-EDA. 45 The exchange repulsion in 1a-l cannot be compensated solely by E elst , and the addition of E ind to the E elst and E exch components is essential to stabilize 1a-l. The E ind component is responsible for approximately 30% of the total attraction in 1a-l.…”

“…2 The aforementioned bond length range is indicative of a metal-ligand bond of the studied σ-complexes featuring a pronounced Sn N character. 45 It is instructive to compare the range of the Sn N bond length for 1a-l with…”

“…44 A broader range of tin dihalides complexed by one and two pyridine molecules were investigated using several quantum chemistry methods in our recent work. 45 The Sn N metal-ligand bond in the resulting coordination compounds featured a dominate ionic character with a minor covalent contribution. This is in agreement with the NBO prediction of the nature of the Sn N bond between the fluorinated benzeneselenolate of Sn(II) and pyridine.…”

Generalized Kohn‐Sham energy decomposition analysis and its applications

“…Metal‐ligand interactions play important roles in nanocrystals, molecular recognition, drug design, metalloprotein chemistry, and so on. Both GKS‐EDA and LMO‐EDA have been employed in the interpretations of various metal‐ligand interactions, which are not trivial tasks due to the inherent complexity of the arrangement of electrons in d‐ and f‐metal‐atom orbitals coupled with the various ligands.…”