Synthesis and structural studies of hexafluorophosphate-based organic salts: A combined experimental and computational analysis

Abstract The neutral ligands 2-(N-2,6-dimethylphenylformimino)furan (L1), 2-(N-2,6-diisopropylphenylformimino)furan (L2), 2-(N-2,6-dimethylphenylformimino) thiophene (L3) and 2-(N-2,6-diisopropylphenylformimino)thiophene (L4) were reacted with half equivalent of bis(allyl)di-μ-chloroodipalladium in the presence of thallium hexafluorophosphate, in dichloromethane, affording the corresponding iminium salts [(N-allyl) (L^L′)][PF6] (L^L’ = L1 (1), L2 (2), L3 (3) or L4 (4)) containing one allyl group linked to the ligand through the imine nitrogen. All new organic salts 1 (C13H13NO)[PF6], 2 (C17H21NO)[PF6], 3 (C13H13NS)[PF6], and 4 (C17H21NS)[PF6] have been characterized by elemental analysis and 1H, 19F, 31P NMR spectroscopy. Structural features in the solid state of compounds 2 and 3 were further discussed by means of X-ray crystallography, Hirshfeld surfaces HS analysis and Non-Covalent Interactions NCI-RDG topological approach. Both crystalline structures are internally stabilized via C–H⋯N1 H-bonds. Supramolecular assemblies are insured by non-conventional C–H⋯F (inter) hydrogen bonds, Cg … Cg (π … π) stacking and C–H … Cg(π) intercontacts, as well as by van der Waals interactions and steric repulsions. Additionally, conceptual DFT global reactivity indicators, calculated at the wB97X-D/cc-pVDZ level, show that studied systems are considered strong electrophiles and marginal nucleophiles.