Analysis of N—H...O hydrogen bonds in new C(O)—NH—P(O)-based phosphoric triamides and analogous structures deposited in the Cambridge Structural Database

Abstract

Five new compounds belonging to the phosphoric triamide family have been synthesized: two of them with the formula XC(O)NHP(O)Y [X = CF3 (1) and CClF2 (2), Y = NHCH2C(CH3)2CH2NH] involving a 1,3-diazaphosphorinane ring part, and three 2,6-Cl2C6H3C(O)NHP(O)Z2 phosphoric triamides [Z = NHC(CH3)3 (3), N(CH3)(C6H11) (4) and N(CH3)(CH2C6H5) (5)]. The characterization was performed by 31P{1H}, 1H, 13C NMR, IR spectroscopy besides 19F NMR for fluorine containing compounds (1) and (2), and X-ray single-crystal structure analysis for (1), (3), (4) and (5). In each molecule the P atom has a distorted tetrahedral environment. The N atoms bonded to P atom have mainly sp2 character with a very slight tendency to a pyramidal coordination for some amido groups. Different types of N—H⋯O hydrogen bonds have been analyzed for (1), (3), (4) and (5) and 118 other structures (including 194 hydrogen bonds) deposited in the Cambridge Structural Database, containing either C(O)—NH—P(O)[N(C)(C)]2 or C(O)—NH—P(O)[NH(C)]2. The participation of NCP—H⋯O=P [NCP = the nitrogen atom of the C(O)—NH—P(O) fragment], N—H⋯O=P, N—H⋯O=C and NCP—H⋯O=C hydrogen bonds in different hydrogen-bonded motifs are discussed. Moreover, the involvement of the O atoms of C=O or P=O in the [NCP—H][N—H]⋯O=P, [N—H]2⋯O=P, [N—H]2⋯O=C and [N—H]3⋯O=C groups are considered. A histogram of N⋯O distances, the distribution of N—H⋯O angles and the scatterplot of N—H⋯O angles versus N⋯O distances are studied.