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

Abstract

Different orientations of P(O) versus C(O) in P(O)NHC(O) skeleton have been discussed in two new phosphorus(V)-nitrogen compounds with formula XP(O)Y and XP(O)Z 2 where X = NHC(O)C 6 H 4 (4-F) and Y = NHCH 2 C(CH 3 ) 2 CH 2 NH (1), Z = NHC 6 H 4 (4-CH 3 ) (2). Compound 1 is the first example of an aliphatic diazaphosphorinane with a gauche orientation which has been studied by X-ray crystallography; the P=O bond is in the equatorial position of the ring. Both compounds show n J(F,C) and m J(F,H) coupling constants (n = 1, 2, 3 and 4; m = 3 and 4) and 3 J(P,C) [ 2 J(P,C). Quantum chemical calculations were performed with HF and Density Functional Theory (DFT) methods using 6-31?G(d,p) basis set. A tentative assignment of the observed vibrational bands for these molecules is discussed. Compound 1 shows a deshielded C atom of the carbonyl moiety (in 13 C NMR spectrum) relative to that of 2, which is supported by IR spectroscopy in which the considerably lower C=O frequency is observed for 1. Comparing the X-ray crystallography and IR spectra of 1 and 2 shows that the acyclic compound 2, containing P=O and C=O bonds in an anti position, are involving in a stronger N-HÁÁÁO=P hydrogen bond in crystal network. This leads to a weaker P=O and N C(O)NHP(O) -H bonds and stronger NÁÁÁO interaction. The N amide -H is involved in an intramolecular N-HÁÁÁO hydrogen bond.

Hirshfeld surface analysis of new phosphoramidates

“…In the 1,3,2-diazaphosphinane ring part of heterocyclic compound (2), the P O bond is placed in an equatorial position relative to the ring, attributed to the endo anomeric effect (Bentrude et al, 1991), and the P-N C(O)NHP(O) bond is in an axial position. In agreement with the previous studies (Tarahhomi et al, 2011), the P-N bonds for (1) and (2) are shorter than the related P-N C(O)NHP(O) bond (Table S1 of (Table S1) are comparable to those in similar compounds (Sabbaghi et al, 2011;Pourayoubi, Nečas & Negari, 2012). For (5) and (6) the P O, P-O and P-N bond lengths and the P-O-P angles are within the expected values for analogous compounds with a P(O)OP(O) fragment (Pourayoubi, Views of the crystal packing diagrams for molecules (a) (1), showing R 2 4 ð16Þ, R 4 4 ð22Þ, R 4 4 ð30Þ and R 2 2 ð8Þ rings [the C-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds are marked as: the C27-H27AÁ Á ÁO1 iv (marked a), C19-H19Á Á ÁO2 i (marked b), N4-H4NÁ Á ÁO2 (marked c), N1-H1NÁ Á ÁO4 (marked d) and C4-H4Á Á ÁO4 ii (marked e)]; (b) (2), with R 2 2 ð10Þ, R 3 3 ð10Þ and R 3 3 ð12Þ rings parallel to [100]; (c) (6), including R 2 2 ð12Þ rings parallel to [001] [the 4-CH 3 -C 6 H 4 substituents are shown as balls (bigger balls) for clarity], via the HÁ Á ÁO interactions in (a), the N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds in (b) and the N-HÁ Á ÁO hydrogen bonds in (c), shown as dashed lines.…”

“…In all compounds the P atoms display a distorted tetrahedral environment and the P O bond lengths are standard for the phosphoramidates . In the C(O)NHP(O) segment of (1), the phosphoryl and carbonyl groups adopt an anti orientation with respect to one another and in (2), similar to the previously reported C(O)NHP(O)-based 1,3,2diazaphosphinanes (Tarahhomi et al, 2011;Pourayoubi et al, 2013), they are in a gauche situation. In the 1,3,2-diazaphosphinane ring part of heterocyclic compound (2), the P O bond is placed in an equatorial position relative to the ring, attributed to the endo anomeric effect (Bentrude et al, 1991), and the P-N C(O)NHP(O) bond is in an axial position.…”

“…The crystallographic data and details of the X-ray analysis of (1)-(6) are given in Table 1. 1 The Hirshfeld surface three-dimensional maps of (1)-(6) and also of the two previously reported structures, 7 Tarahhomi et al, 2011) and (8) (a monoclinic polymorph of (6), Pourayoubi, Fadaei et al, 2012), are given in Figs. 2 and 3 with the color coded for the figures [for (2), the HS of only the phosphoric triamide molecule is generated].…”

Different cyclic motifs in phosphoric triamides containing a C(O)NHP(O)(NH)2skeleton and anR22(10) graph set in three new compounds: a database analysis of hydrogen-bond strengths based on motifs

“…A search for phosphoric triamides with a C(O)NHP(O) skeleton in the CSD and recently published papers (Pourayoubi, Tarahhomi et al, 2010aTarahhomi et al, ,b, 2011Pourayoubi, Rostami Chaijan et al, 2011a,b;Pourayoubi & Saneei, 2011;Raissi Shabari et al, 2011;Tarahhomi et al, 2011;Toghraee et al, 2011) shows that the strongest N-HÁ Á ÁO hydrogen bonds are found for P OÁ Á ÁH-N C(O)NHP(O) hydrogen bonds, especially in the R 2 2 (8) rings of some molecules [in the case of a syn orientation of P O versus N-H which allows the building of the cyclic motif through a pair of P OÁ Á ÁH-N C(O)NHP(O) hydrogen bonds]. A histogram of the NÁ Á ÁO distances in these N-HÁ Á ÁO hydrogen bonds is given in Fig.…”

Interplay of thermochemistry and Structural Chemistry, the Journal (volume 22, 2011, issues 1–3) and the discipline

“…The issue continues with the study by Tarahhomi et al [62] in which orientation of O-atoms P(O)NHC(O) moiety of N-carbonyl phosphoramidates has been studied on the examples of two newly synthesized compounds XP(O)Y and XP(O)Z 2 (X = NHC(O)C 6 H 4 (4-F); Y = NHCH 2 C (CH 3 ) 2 CH 2 NH; Z = NHC 6 H 4 (4-CH 3 ). The synthesized compounds have been characterized by DFT, NMR spectroscopy.…”