The synergistic cooperation of NH⋯O and CH⋯O hydrogen bonds in the structures of three new phosphoric triamides

• Published in: Phosphorus, sulfur, and silicon and the related elements sulfur, and silicon and the related elements, 2018-04, Vol.193 (4), p.257-266
• Main Authors: Saneei, Anahid, Pourayoubi, Mehrdad, Jasinski, Jerry P., Jenny, Titus A., Crochet, Aurelien, Fromm, Katharina M., Keeley, Amanda C.
• Format: Article
• Language: English
• Subjects: 2D NMR spectroscopy; Hirshfeld surface analysis; hydrogen bond; Phosphoric triamide; supramolecular assembly
• ISSN: 1042-6507; 1563-5325
• DOI: 10.1080/10426507.2017.1399128

The supramolecular assemblies of three new phosphoric triamides, {(C 6 H 5 CH 2 )(CH 3 )N} 2 (4-CH 3 -C 6 H 4 C(O)NH)P(O) (1), {(C 6 H 11 )(CH 3 )N} 2 (4-CH 3 -C 6 H 4 C(O)NH)P(O) (2) and {(C 2 H 5 ) 2 N} 2 (4-CH 3 -C 6 H 4 C(O)NH)P(O) (3) were studied by single crystal X-ray diffraction as well as by Hirshfeld surface analysis. It was found that a synergistic cooperation of NH⋯O and CH⋯O hydrogen bonds occurs in all three structures, but forming unique supramolecular architectures individually. Along with the presence of centrosymmetric dimers in 1, 2 and 3, based on a classical NH⋯O hydrogen bond, the presence of weak CH⋯O interactions play an additional and vital role in crystal architecture and construction of the final assemblies, collectively identified as a centrosymmetric dimer (0D), a 1-D array and a 3-D network, respectively. These differences in superstructures are related to the effect of aromatic, bulk and flexible groups used in the molecules designed, with a similar C(O)NHP(O) backbone. The NH⋯O contacts in 1, 2 and 3 are of the "resonance-assisted hydrogen bond" types and also the anti-cooperativity effect can be considered in the multi-acceptor sites P═O in 1 and 2 and C═O in 3. All three compounds were further studied by 1D NMR experiments, 2D NMR techniques (HMQC and HMBC (H-C correlation)), high resolution ESI-MS, EI-MS spectrometry and IR spectroscopy methods.