Through space spin-spin coupling constant transmission pathways in 2-(trifluoromethyl)thiophenol: formation of unusual stabilizing bifurcated CF HS and CF SH interactions

• Published in: Physical chemistry chemical physics : PCCP Vol. 23; no. 15; pp. 98 - 988
• Main Authors: Port, Vinícius C, Zeoly, Lucas A, Coelho, Fernando, Cormanich, Rodrigo A
• Format: Journal Article
• Published: 22.04.2021
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d0cp05887d

Given its importance and the possibility of organic F to participate in hydrogen bonds (H-bonds), the understanding of its behavior as a H-bond acceptor with different donors is crucial. The interest in organofluorine compounds and the works related to the study of the participation of this atom in non-covalent interactions is constantly growing. Following recent studies in this subject, we evaluated the existence of two bifurcated intramolecular interactions, a bifurcated CF HS H-bond in the cis conformer of 2-trifluoromethylthiophenol and an unusual, bifurcated CF SH interaction in the trans conformer. The J FH spin-spin coupling constant (SSCC) was evaluated for 2-trifluoromethylthiophenol both experimentally by 1 H and 19 F NMR and theoretically using the natural bond orbitals (NBO), the quantum theory of atoms in molecules (QTAIM) and the non-covalent interactions (NCI) framework. Although both interactions are crucial for the stabilization of the conformer geometries, the observed positive J FH spin-spin coupling constant (SSCC) is mainly resultant from the trans conformer, which has a large calculated positive SSCC, and is transmitted through steric interactions involving the F lone pairs and the σ SH bonding orbital. Experimental and theoretical evidences of formation of unusual bifurcated CF HS hydrogen bonds and CF SH stabilizing interactions and their implications to the observed through space J FH spin spin coupling in 2-(trifluoromethyl)thiophenol.