The first naphthodiazaphosphorinane in the solid phase; syntheses, spectroscopic studies and X-ray crystallography of some new 1,3,2-diheterophosphorus compounds

Abstract

New heterocyclic compounds of diazaphosphorinanes, diazaphospholes, and oxazaphospholes were synthesized and characterized by 1 H, 13 C, 31 P, NMR, IR spectroscopy, and CHN elemental analysis. The 3D structure of compound (5) was determined by X-ray crystallography. Since benzo-or naphthodiazaphospholes/diazaphosphorinanes containing aromatic rings are usually unstable in the solution state, their single crystal structures are rarely reported and, to the best of our knowledge, this structure is the first occasion of naphthodiazaphosphorinanes obtained here. It is noticeable that the P=O and C=O bonds are closer to syn than anti configuration and the P=O bond is placed in a pseudoequatorial position. This structure produced a 3D polymeric chain via strong hydrogen bonds and electrostatic short contacts. Due to the ring strain of five-membered rings, for all diazaphospholes great 2 J(PNH endocyclic ) coupling constants (about 18.0 Hz), as well as high 2,3 J(P,C) coupling constants for the aromatic carbon atoms connected to the five-membered ring (about 14.5, 13.5 Hz, respectively) were measured. Replacement of one NH group in a diazaphosphole ring by an oxygen atom caused exceedingly decreased ring strain and hence highly diminished 2 J(PNH endocyclic ) coupling constant.Furthermore, 31 P NMR spectra of oxazaphospholes, like the spectra of diazaphosphorinanes, indicated highly shielded phosphorus atoms relative to those of their diazaphospholes analogs.

Polymorphism for a novel phosphoramidate; NMR and X-ray crystallography

“…Similar results were obtained for the nitrogen atoms of structure 2b that confirm the sp 2 hybridization for the N atoms, although due to the repulsion and steric interactions, some angles are greater, and others are smaller than 120°. This observation suggests the existence of partial multiple bond character between phosphorus and nitrogen atoms that has always been confirmed by the crystallographic data of our previously reported similar compounds [29][30][31][32][33][34].…”

Different orientations of C=O versus P=O in P(O)NHC(O) skeleton: the first study on an aliphatic diazaphosphorinane with a gauche orientation

“…Considering the Karplus equation [25] and the torsion angles of about ±70°for P-N-C-H axial and ±170°for P-N-C-H equatorial obtained from X-ray crystallography, the value of 26.3 Hz is assigned to 3 J(PNCH equatorial ). This is larger than the 3 J(PNCH) values for acyclic phosphoramidates, for example in compound CCl 3 2 3 J(P,H) = 10.2 and 9.1 Hz for CH 3 and CH 2 units [10]. The phosphorus-H axial coupling is not observed.…”

“…The study on O atoms' orientation in P(O)NHC(O) moiety of N-carbonyl phosphoramidates is important because of the structural features, hydrogen bonding patterns, and binding manner to metal cations [1][2][3][4][5]. The anti orientation is preferred for the C=O versus P=O unit [6,7].…”

“…Some researchers have employed the anionic form [P(O)NC(O)] -to obtain compounds with a non-anti orientation [8] and better donority properties [9]. Despite the numerous structures reported in this series [10][11][12][13][14][15][16][17][18][19], there are a few neutral structures with synclinal orientation [2,5,[13][14][15][16][17]19]. Here, we study on two new compounds with different orientations of C=O versus P=O.…”

“…The phosphorus atoms have a distorted tetrahedral configuration with the bond angles in the range of 101.29(12)The phosphoryl and carbonyl groups adopt an anti position in 2, whereas they are in a gauche situation in 1. Many phosphoric triamides of the type RC(O)NHP(O)[NR 1 R 2 ] 2 have been investigated structurally[1, 2, 5-7, 10, 11, 13-19, 27-55]; however, the nonanti orientation has been observed for a few molecules[2,5,[13][14][15][16][17][18][19]. In Tables S1 and S2 (Supplementary material), some structural parameters of selected molecules with different conformations are gathered.…”