Evaluation of N–H···O hydrogen bond interactions in two new phosphoric triamides with a P(O)[NHCH(CH3)2]2 segment by means of topological (AIM) calculations, Hirshfeld surface analysis and 3D energy framework approach

International audienceTwo new phosphoric triamides having a common part XP(O)[NHCH(CH3)(2)](2), with X=[2,3,6-F-3-C6H2C(O) NH] (1) and [C6H11(CH3)N](2), were prepared and characterized by spectroscopic techniques (FT-IR and H-1-, C-13-, P-31-NMR) and single crystal X-ray diffraction. The asymmetric unit of 1 is composed of one molecule, whereas for 2 it consists of six symmetry independent molecules. In all molecules, the P atoms are in a distorted tetrahedral environment of one oxygen and three nitrogen atoms. The latter have mainly sp(2) character and a nearly planar environment. The crystal structures are stabilized via N-H center dot center dot center dot O hydrogen bond interactions, forming a linear arrangement for 1 and three independent parallel linear chains for 2, along the b and a axis, respectively. The intermolecular interactions in the molecular packing were analyzed using the Hirshfeld surface methodology, two-dimensional (2D) fingerprint plots and enrichment ratios (E). The prevalent interactions revealed by Hirshfeld surfaces are O center dot center dot center dot H type interactions for both structures land 2, additionally C center dot center dot center dot O for 1 and H center dot center dot center dot H interactions for 2. The most favored contacts responsible for the molecular packing are C center dot center dot center dot F, N center dot center dot center dot H and O center dot center dot center dot H for 1 confirmed by E values greater than 1.30, whereas for 2, O center dot center dot center dot H and N center dot center dot center dot H intermolecular interactions with E values about 1.04 representing the favored contacts. Thus, the N-H center dot center dot center dot O hydrogen bond interactions are the dominant interactions in both compounds. For more details, a topological AIM analysis of N-H center dot center dot center dot O hydrogen bond interactions was performed: N-CP -H center dot center dot center dot O=C hydrogen bond (the N-CP is referred to the nitrogen atom within the C(O)NHP(O) segment) interactions in 1 are stronger than N H center dot center dot center dot O=P interactions in both 1 and 2. Furthermore, a 3D topology of the molecular packing via the energy framework approach showed that the N-H center dot center dot center dot O hydrogen bond interactions in C(O)NHP(O)-based phosphoric triamide are predominantly electrostatic based, while they are electrostaticdispersion based for other phosphoric triamides with a [N] P(O)[NH](2) skeleton