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.
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: (+44) 1223-336-033, or e-mail: [email protected].