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NMR and theoretical analyses of electronic effects in N-BH3 adducts of (1,3,5-dithiazin-2-yl)silanes and stannanes. Intramolecular interactions of chemically identical S···S atoms

2022; Elsevier BV; Volume: 1270; Linguagem: Inglês

10.1016/j.molstruc.2022.133938

1872-8014

Angelina Flores‐Parra, Pedro Montes‐Tolentino, Germán Rodrı́guez-López, I. Ramos-Garcia, Tayde Osvaldo Villaseñor-Granados,

N-Heterocyclic Carbenes in Organic and Inorganic Chemistry

• N-BH 3 adducts of (5-methyl-1,3,5-dithiazin-2-yl)silanes and stannanes; • Long-distance electronic effects detected by NMR spectroscopy; • Theoretical analysis of weak intramolecular interactions; • Through-the-space S•••S, S•••Si and S•••Sn intramolecular interactions; • Intramolecular interactions in chemically identical sulphur-sulphur atoms. The electronic effects produced by BH 3 coordination to SiMe 2 Dtz 2 , SiMeDtz 3 , SiPhDtz 3 , SnMeDtz 3 and SnPhDtz 3 (Dtz = 5-methyl-1,3,5-dithiazinan-2-yl group) have been studied by 1 H, 13 C, 11 B, 29 Si and 119 Sn NMR spectroscopy. It has been found that these effects are transmitted until seven bonds away. The X-ray diffraction analyses of SiMe 2 Dtz 2 and its diborane adduct SiMe 2 (DtzBH 3 ) 2 showed for the latter an unexpected, folded conformation that facilitates intramolecular chemically identical sulphur-sulphur interactions. The existence of S•••S, S•••Si and S•••Sn stabilising weak interactions was confirmed by ab-initio calculations, especially by the reduced gradient and the electrostatic potential of the electronic density maps. The electronic withdrawal effect of the N→BH 3 groups drastically modifies the NBO charges of the sulphur atoms and their intramolecular interactions. It has concluded that the sulphur lone pairs interactions through-the-space explain the molecules conformation and the long-distance electronic effects.