ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Different molecular assemblies in two new phosphoric triamides with the same C(O)NHP(O)(NH)₂ skeleton: crystallographic study and Hirshfeld surface analysis

Anahid Saneei, Mehrdad Pourayoubi, Titus A. Jenny, Aurelien Crochet, Katharina M. Fromm, and Ekaterina S. Shchegravina

Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran

E-mail: pourayoubi@um.ac.ir

Abstract: Different molecular assemblies were compared in two new structures [4-CH₃-C₆H₄C(O)NH]P(O)[NH]₂(CH₂)₃, 1, and [4-CH₃-C₆H₄C(O)NH]P(O)[NHC₆H₃(3,4-CH₃)₂]₂, 2, belonging to the families of “cyclic phosphoric triamide” and “phosphoric triamide”, respectively. The differences in the hydrogen bond motifs were discussed (by single crystal X-ray diffraction) as a result of three factors: (1) action of two N atoms with a non-planar environment in 1 as an H-bond acceptor, (2) different orientations of three N–H bond vectors in two molecules and (3) different conformations of C=O and P=O groups. These differences lead to more complicated hydrogen bond pattern of 1, with respect to that of 2, as structure 1 may be considered as a model of four-acceptor–three-donor versus a two-acceptor–three-donor system in 2. The main discrepancies of 1 and 2, monitored by the Hirshfeld surface analysis, are related to the contribution portions of O···H/H···O contacts, in which compound 1 not only involves the greater existence of classical hydrogen bonds but also contains the further C–H···O weak interactions in its crystal packing with respect to compound 2. Instead, in 2, the shortage of O···H/H···O contacts has been partially compensated by the C···H/H···C interactions, due to the presence of more unsaturated carbon acceptors. The differences in assemblies are also reflected in the solid-state IR spectra, especially for the N–H vibration frequencies. The new compounds were further studied by 1D NMR experiments (¹H, ¹³C, ³¹P), 2D NMR techniques [HMQC and HMBC (H–C correlation), HSQC (N–H correlation)], high-resolution ESI–MS, EI–MS spectrometry and IR spectroscopy.

Keywords: Phosphoric triamide; Molecular assembly; Hydrogen bonding pattern; Hirshfeld surface analysis; NMR spectroscopy

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-017-0168-x

Chemical Papers 71 (10) 1809–1823 (2017)