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

GRAPHICAL ABSTRACT

ABSTRACT

The supramolecular assemblies of three new phosphoric triamides, {(C₆H₅CH₂)(CH₃)N}₂(4-CH₃-C₆H₄C(O)NH)P(O) (1), {(C₆H₁₁)(CH₃)N}₂(4-CH₃-C₆H₄C(O)NH)P(O) (2) and {(C₂H₅)₂N}₂(4-CH₃-C₆H₄C(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.

KEYWORDS:

• Phosphoric triamide
• hydrogen bond
• supramolecular assembly
• Hirshfeld surface analysis
• 2D NMR spectroscopy

Acknowledgments

Support of this investigation by Ferdowsi University of Mashhad (Project No. 3/28386) is gratefully acknowledged. Jerry P. Jasinski acknowledges the NSF-MRI program (grant No. CHE-1039027) for funds to purchase the X-ray diffractometer to perform the crystallography experiments of structures 1 and 2. For structure 3, the X-ray crystallography experiment was supported by FriMat, University of Fribourg.

Supplementary data

CCDC 1045700, 1030528 and 1030678 contain the supplementary crystallographic data for 1, 2 and 3. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: [phone], or e-mail: [email protected].