Structural analysis of bis-amidines and bis-nitriles in solid-state by combining NMR spectroscopy and molecular modeling

The paper presents the analysis of the structures of four novel sulfonamide-based bis-amidines, and four novel interesting intermediates leading to them, named bis-nitriles, in solid-state based on C-13 CP/MAS NMR spectroscopy and theoretical calculations of shielding constants at DFT level of theory. We have observed double C-13 resonances in solid-state spectra as compared with solution spectra. The considerations of experimental chemical shifts followed by shielding computations allowed us to define essential geometric details regarding the most probable conformations in solid-state. All compounds have one independent molecule in the asymmetric unit, and a main reason of splittings of NMR signals in solid-state is different orientation of alkoxy fragments (methyl groups and linker) with reference to benzene rings. (c) 2009 Elsevier B.V. All rights reserved.