The first C(O)NHP(O)-based phosphoric triamide structure with an N‒H···π hydrogen bonding: A combination of X-ray crystallography and theoretical study to evaluate the strength of hydrogen bonds

GRAPHICAL ABSTRACT

ABSTRACT

The hydrogen bond pattern of N-(4-methoxybenzoyl)-N′,N″-bis(4-methylbenzyl)-phosphoric triamide, C₂₄H₂₈N₃O₃P, (I), was investigated. In the crystal structure, the molecules are aggregated through N_CP―H···O═P and N_P―H···O═C hydrogen bonds in a one-dimensional arrangement parallel to the c axis (N_CP is the nitrogen atom in the C(O)NHP(O) segment and N_P stands for the two other nitrogen atoms bonded to the P atom). There is also a novel N_P‒H···π hydrogen bond in the crystal which extends the aggregation of the molecules to a two-dimensional array parallel to the bc plane. A Cambridge Structural Database (CSD, version 5.37, Feb 2016) analysis shows that the N―H···π hydrogen bond was not observed in any of 156 [RC(O)NH]P(O)[NR¹R²]₂ (R¹ ≠ H, R² = H or ≠ H) phosphoric triamide structures reported so far. The theoretical calculations at the B3LYP/6-311G^** level of theory (DFT, AIM, and NBO) were performed to evaluate the strengths of N_CP―H···O═P, N_P―H···O═C and N_P―H···π hydrogen bonds, considering two-aggregate molecular assemblies containing these hydrogen bonds. The calculations on the title compound suggest that the intermolecular N_CP―H···O═P hydrogen bond is stronger than N_P―H···O═C and N_P―H···π interactions. The hydrogen bond strength was investigated by NBO, topological analysis, geometry calculation, Hirshfeld surface analysis and experimental spectroscopic results, which are in agreement with each other.

KEYWORDS:

• Phosphoric triamide
• X-ray diffraction
• N‒H···O hydrogen bond
• N‒H···π hydrogen bond
• DFT calculation
• Hirshfeld surface analysis

Acknowledgments

MT and MP acknowledge Ferdowsi University of Mashhad for laboratories and spectroscopic measurements facilities. We acknowledge the CF X-ray diffraction and Bio-SAXS supported by the CIISB research infrastructure (LM2015043 funded by MEYS CR) for their support with obtaining scientific data presented in this paper.

Funding

This research has been financially supported by the Ministry of Education, Youth and Sports of the Czech Republic under the project CEITEC 2020 (LQ1601). MT and MP thank the financial support of part of this work by Ferdowsi University of Mashhad (Project No. 3/28383).