Bankiewicz B, Kupfer S, Matczak P. Tuning the metal-ligand bond in the σ-complexes of stannylenes and azabenzenes.
J Comput Chem 2021;
42:2103-2115. [PMID:
34420225 DOI:
10.1002/jcc.26741]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/01/2021] [Accepted: 07/26/2021] [Indexed: 11/10/2022]
Abstract
The metal-ligand bond in a set of 60 σ-complexes has been investigated by electronic structure computations. These σ-complexes originate from the unique combination of 12 stannylenes (SnX2 ) with five azabenzene ligands (pyridine, pyrazine, pyrimidine, pyridazine, and s-triazine), where the nitrogen center of the ligand acts as σ-donor and the tin(II) center as σ-acceptor in a 1:1 fashion. The Sn ← N bond and the total interaction between the stannylene and azabenzene moieties of the σ-complexes are characterized in depth to relate the Sn ← N strength to the substitution pattern at SnX2 and to the number and the positioning of N atoms in the azabenzenes. Such X substituents as (iso)cyano and trifluoromethyl groups enhance the interaction strength, while the presence of alkyl, phenyl, and silyl substituents in SnX2 diminishes the stability of σ-complexes. A gradual weakening of the total interaction is associated with the growing number of N atoms in the azabenzenes, while the N-atom positioning in pyridazine is particularly effective in strengthening the interaction with stannylenes. Variations in the Sn ← N bond strength usually follow those in the total interaction between the moieties but the interacting quantum atoms picture of Sn ← N reveals certain intriguing exceptions.
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