Study on H-bond patterns in phosphoric triamides having a P(O)NHC(O) skeleton, a gauche orientation of P(O) vs C(O) in new compounds

Conformational flexibility in amidophosphoesters: a CSD analysis completed with two new crystal structures of (C6H5O)2P(O)X [X = NHC7H13 and N(CH2C6H5)2]

The crystal structures of diphenyl (cycloheptylamido)phosphate, C19H24NO3P or (C6H5O)2P(O)(NHC7H13), (I), and diphenyl (dibenzylamido)phosphate, C26H24NO3P or (C6H5O)2P(O)[N(CH2C6H5)2], (II), are reported. The NHC7H13 group in (I) provides two significant hydrogen-donor sites in N—H...O and C—H...O hydrogen bonds, needed for a one-dimensional hydrogen-bond pattern along [100] in the crystal, while (II), with a (C6H5CH2)2N moiety, lacks these hydrogen bonds, but its three-dimensional supramolecular structure is mediated by C—H...π interactions. The conformational behaviour of the phenyl rings in (I), (II) and analogous structures from the Cambridge Structural Database (CSD) were studied in terms of flexibility, volume of the other group attached to phosphorus and packing forces. From this study, synclinal (±sc), anticlinal (±ac) and antiperiplanar (±ap) conformations were found to occur. In the structure of (II), there is an intramolecular C ortho —H...O interaction that imposes a +sc conformation for the phenyl ring involved. For the structures from the CSD, the +sc and ±ap conformations appear to be mainly imposed by similar C ortho —H...O intramolecular interactions. The large contribution of the C...H/H...C contacts (32.3%) in the two-dimensional fingerprint plots of (II) is a result of the C—H...π interactions. The differential scanning calorimetry (DSC) analyses exhibit peak temperatures (T m) at 109 and 81 °C for (I) and (II), respectively, which agree with the strengths of the intermolecular contacts and the melting points.

Decorated single-enantiomer phosphoramide-based silica/magnetic nanocomposites for direct enantioseparation

The nano-composites Fe₃O₄@SiO₂@PTA(+) and Fe₃O₄@SiO₂@PTA(−) (PTA: phosphoric triamide) were prepared and used for the chiral separation of five racemic mixtures.

Newrac-XP(O)(OC6H5)(NHC6H4-p-CH3) [X= N(CH3)(cyclo-C6H11) and NH(C3H5)] andrac-(C6H5CH2NH)P(O)(OC6H5)(NH-cyclo-C6H11) mixed-amide phosphinates

The mixed-amide phosphinates,rac-phenyl (N-methylcyclohexylamido)(p-tolylamido)phosphinate, C20H27N2O2P, (I), andrac-phenyl (allylamido)(p-tolylamido)phosphinate, C16H19N2O2P, (II), were synthesized from the racemic phosphorus–chlorine compound (R,S)-(Cl)P(O)(OC6H5)(NHC6H4-p-CH3). Furthermore, the phosphorus–chlorine compound ClP(O)(OC6H5)(NH-cyclo-C6H11) was synthesized for the first time and used for the synthesis ofrac-phenyl (benzylamido)(cyclohexylamido)phosphinate, C19H25N2O2P, (III). The strategies for the synthesis of racemic mixed-amide phosphinates are discussed. The P atom in each compound is in a distorted tetrahedral (N1)P(=O)(O)(N2) environment. In (I) and (II), thep-tolylamido substituent makes a longer P—N bond than those involving theN-methylcyclohexylamido and allylamido substituents. In (III), the differences between the P—N bond lengths involving the cyclohexylamido and benzylamido substituents are not significant. In all three structures, the phosphoryl O atom takes part with the N—H unit in hydrogen-bonding interactions,viz.an N—H...O=P hydrogen bond for (I) and (N—H)(N—H)...O=P hydrogen bonds for (II) and (III), building linear arrangements along [001] for (I) and along [010] for (III), and a ladder arrangement along [100] for (II).

Three new [XC(O)NH]P(O)[N(CH2C6H5)2]2phosphoric triamides (X= CClF2, 3-F-C6H4and 3,5-F2-C6H3): a database analysis of tertiary N-atom geometry in compounds with a C(O)NHP(O)[N]2core

In the phosphoric triamidesN,N,N′,N′-tetrabenzyl-N′′-(2-chloro-2,2-difluoroacetyl)phosphoric triamide, C30H29ClF2N3O2P, (I),N,N,N′,N′-tetrabenzyl-N′′-(3-fluorobenzoyl)phosphoric triamide, C35H33FN3O2P, (II), andN,N,N′,N′-tetrabenzyl-N′′-(3,5-difluorobenzoyl)phosphoric triamide, C35H32F2N3O2P, (III), the tertiary N atoms of the dibenzylamido groups havesp2character with minimal deviation from planarity. The sums of the three bond angles about the N atoms in (I)–(III) deviate by less than 8° from the planar value of 360°. The geometries of the tertiary N atoms in all phosphoric triamides with C(O)NHP(O)[N]2skeletons deposited in the Cambridge Structural Database [CSD; Allen (2002).Acta Cryst.B58, 380–388] have been examined and the bond-angle sums at the two tertiary N atoms (SUM1 and SUM2) and the parameter ΔSUM (= SUM1 − SUM2) considered. It was found that in compounds with a considerable ΔSUM value, the more pyramidal N atoms are usually oriented so that the corresponding lone electron pair isantiwith respect to the P=O group. In (I), (II) and (III), the phosphoryl and carbonyl groups, separated by an N atom, areantiwith respect to each other. In the C(O)NHP(O) fragment of (I)–(III), the P—N bond is longer and the O—P—N angle is contracted compared with the other two P—N bonds and the O—P—N angles in the molecules. These effects are also seen in analogous compounds deposited in the CSD. Compounds with [C(O)NH]P(O)[N]X(X≠ N), such as compounds with a [C(O)NH]P(O)[N][O] skeleton, have not been considered here. Also, compounds with a [C(O)NH]2P(O)[N] fragment have not been reported to date. In the crystal structures of all three title compounds, adjacent molecules are linkedviapairs of P=O...H—N hydrogen bonds, forming dimers withCisymmetry.

The double H-atom acceptability of the P=O group in new XP(O)(NHCH2C6H4-2-Cl)2 phosphoramidates [X = C6H5O- and CF3C(O)NH-]: a database analysis of compounds having a P(O)(NHR) group

In the hydrogen-bond patterns of phenyl bis(2-chlorobenzylamido)phosphinate, C(20)H(19)Cl(2)N(2)O(2)P, (I), and N,N'-bis(2-chlorobenzyl)-N''-(2,2,2-trifluoroacetyl)phosphoric triamide, C(16)H(15)Cl(2)F(3)N(3)O(2)P, (II), the O atoms of the related phosphoryl groups act as double H-atom acceptors, so that the P=O···(H-N)(2) hydrogen bond in (I) and the P=O···(H-N(amide))(2) and C=O···H-N(C(O)NHP(O)) hydrogen bonds in (II) are responsible for the aggregation of the molecules in the crystal packing. The presence of a double H-atom acceptor centre is a result of the involvement of a greater number of H-atom donor sites with a smaller number of H-atom acceptor sites in the hydrogen-bonding interactions. This article also reviews structures having a P(O)NH group, with the aim of finding similar three-centre hydrogen bonds in the packing of phosphoramidate compounds. This analysis shows that the factors affecting the preference of the above-mentioned O atom to act as a double H-atom acceptor are: (i) a higher number of H-atom donor sites relative to H-atom acceptor centres in molecules with P(=O)(NH)(3), (N)P(=O)(NH)(2), C(=O)NHP(=O)(NH)(2) and (NH)(2)P(=O)OP(=O)(NH)(2) groups, and (ii) the remarkable H-atom acceptability of this atom relative to the other acceptor centre(s) in molecules containing an OP(=O)(NH)(2) group, with the explanation that the N atom bound to the P atom in almost all of the structures found does not take part in hydrogen bonding as an acceptor. Moreover, the differences in the H-atom acceptability of the phosphoryl O atom relative to the O atom of the alkoxy or phenoxy groups in amidophosphoric acid esters may be illustrated by considering the molecular packing of compounds having (O)(2)P(=O)(NH) and (O)P(=O)(NH)(N)groups, in which the unique N-H unit in the above-mentioned molecules almost always selects the phosphoryl O atom as a partner in forming hydrogen-bond interactions. The P atoms in (I) and (II) are in tetrahedral coordination environments, and the phosphoryl and carbonyl groups in (II) are anti with respect to each other (the P and C groups are separated by one N atom). In the crystal structures of (I) and (II), adjacent molecules are linked via the above-mentioned hydrogen bonds into a linear arrangement parallel to [100] in both cases, in (I) by forming R(2)(2)(8) rings and in (II) through a combination of R(2)(2)(10) and R(2)(1)(6) rings.

N,N'-Dibenzyl-N''-(2,4-difluoro-benzo-yl)-N,N'-dimethyl-phospho-ric triamide

In the title mol-ecule, C(23)H(24)F(2)N(3)O(2)P, the P atom is in a distorted tetra-hedral P(=O)(N)(N)(2) environment, with the bond angles around the P atom in the range 106.78 (11)-114.10 (13)°. The phosphoryl and carbonyl groups, which are separated by an N atom, adopt an anti orientation relative to each other. In the C(=O)NHP(=O) fragment, the P-N bond is longer [1.683 (2) Å] and the O-P-N angle is smaller [106.78 (11)°] than the other P-N bonds [1.613 (2) and 1.632 (2) Å] and O-P-N bond angles [114.10 (13) and 110.83 (12)°], respectively. The N atoms have sp(2) character. In the crystal, pairs of P=O⋯H-N hydrogen bonds form inversion dimers with R(2) (2)(8) ring motifs.

N,N'-Dicyclo-hexyl-N''-(3-fluoro-benzo-yl)-N,N'-dimethyl-phospho-ric triamide

In the title compound, C₂₁H₃₃FN₃O₂P, the P atom has a distorted tetra­hedral environment and the N atoms display geometries consistent with a model of sp² hybridization (with bond-angle sums for the tertiary N atoms of 357.8 and 358.7°). The phosphoryl and carbonyl groups are anti with respect to each other. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R₂²(8) loops.

N,N'-Dibenzyl-N,N'-dimethyl-N''-(2-phenyl-acet-yl)phospho-ric triamide

The P atom in the title mol­ecule, C₂₄H₂₈N₃O₂P, is in a distorted tetra­hedral P(=O)(N)(N)₂ environment. The phosphoryl group and the NH unit adopt a syn orientation with respect to each other and the N atoms have sp² character. The P—N bonds in the P(O)[N(CH₃)(CH₂C₆H₅)]₂ unit are shorter than the P—N bond in the C(=O)NHP(=O) fragment. An intra­molecular C—H⋯O hydrogen bond occurs. In the crystal, pairs of P=O⋯H—N hydrogen bonds form centrosymmetric dimers. C—H⋯O contacts are also observed. Four C atoms of two benzene rings are disordered over two alternative sites with an occupancy ratio of 0.523 (12):0.427 (12).

O-Phenyl (tert-butyl-amido)(p-tolyl-amido)-phosphinate

In the title mol­ecule, C₁₇H₂₃N₂O₂P, the P atom has a distorted tetra­hedral environment. The P—N bond to the tolyl­amido fragment is 1.642 (4) Å while that to the butyl­amido fragment is 1.629 (3) Å. The dihedral angle between the two benzene rings is 82.3 (2)°. In the crystal, adjacent mol­ecules are linked via weak N—H⋯(O)P and N—H⋯N hydrogen-bonding inter­actions into an extended chain parallel to the b axis. The three methyl groups of the tert-butyl­amido substituent are disordered over two sets of sites with equal occupancies. The crystal studied was found to be a non-merohedral twin with the minor twin component = 23.1 (1)%.

N,N'-Dibenzyl-N,N'-dimethyl-N''-(p-tol-yl)phospho-ric triamide

The asymmetric unit of the title compound, C(23)H(28)N(3)OP, contains two independent mol-ecules with significant conformational differences. For example, the torsion angles N-C-C-C involving the N-benzyl moieties are 57.3 (7) and 11.6 (8)° in one mol-ecule and 76.5 (7) and 97.4 (7)° in the other. In each mol-ecule, the P atom exhibits a distorted tetra-hedral conformation [the bond angles at P are in the ranges 104.7 (2)-115.2 (2) and 105.1 (2)-115.1 (2)° in the two molecules], and the phosphoryl group and the N-H group adopt an anti orientation with respect to one another. In the crystal, mol-ecules are linked via N-H⋯O(P) hydrogen bonds, forming a chain parallel to the a axis.

N-(3-Fluorobenzoyl)-N′,N′′-bis(4-methylphenyl)phosphoric triamide

In the title compound, C₂₁H₂₁FN₃O₂P, the NH and P(=O) groups of the C(=O)NHP(=O) fragment are in a syn arrangement with respect to each other, as are the two amide H atoms of the two CH₃–4-C₆H₄–NH moieties. In the crystal, mol­ecules are linked through N—H⋯O(=P) and N—H⋯O(=C) hydrogen bonds, forming R₂²(8) and R₂²(12) rings, which are arranged in chains parallel to [010].

N,N'-Dicyclo-hexyl-N''-(2,6-difluoro-benzo-yl)-N,N'-dimethyl-phospho-ric triamide

In the title mol-ecule, C(21)H(32)F(2)N(3)O(2)P, the P=O and N-H groups are syn with respect to each other, and the P atom is bonded in a distorted tetra-hedral environment. The phosphoryl group adopts an anti orientation with respect to the carbonyl group. The angles at the tertiary N atoms (with bond-angle sums of 358.4 and 357.0°) confirm their sp(2) character. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds generate R(2) (2)(8) loops.

N,N'-Bis(2-methyl-phen-yl)-N''-(2,2,2-trichloro-acet-yl)phospho-ric triamide

In the title compound, C₁₆H₁₇Cl₃N₃O₂P, the P—N bonds in the P(O)[NH(2—CH₃)C₆H₄]₂ unit [1.623 (4) and 1.637 (3) Å] are shorter than the P—N bond in the C(O)NHP(O) fragment [1.704 (3) Å]. The phosphoryl and carbonyl groups are anti with respect to each other and the P atom has a distorted tetra­hedral configuration. In the crystal, adjacent mol­ecules are linked via N—H⋯O(P) and N—H⋯O(C) hydrogen bonds into an extended chain parallel to [101].

Diphenyl [(S)-1-phenylpropanamido]-phosphate

The title compound, C₂₁H₂₂NO₃P, was synthesized from the reaction of (C₆H₅O)₂P(O)(Cl) and S-1-phenyl­propyl­amine (1:2 mole ratio) at 273 K, followed by removal of the S-1-phenyl­propyl­amine hydro­chloride by-product by dissolving in H₂O. The P atom is located in a distorted tetra­hedral environment. The bond angles at the P atom vary from 99.51 (12) to 116.68 (12)°. The sp² character of the N atom is reflected by the C—N—P angle [120.9 (2)°]. The P=O group and the N—H unit adopt an anti orientation with respect to one another. In the crystal, adjacent mol­ecules are linked via N—H⋯O(P) hydrogen bonds into a one-dimensional arrangement running parallel to the a axis.

N-(2,6-Difluoro-benzo-yl)-P,P-bis-(pyrrolidin-1-yl)phosphinic amide

The phosphoryl and carbonyl groups in the title compound, C₁₅H₂₀F₂N₃O₂P, are anti with respect to each other (but the P- and C-groups are separated by another atom) and the P atom is in a tetra­hedral coordination environment. Two C atoms in one of the pyrrolidinyl fragments are disordered over two sets of sites with occupancies of 0.746 (8) and 0.254 (8). The environments of the pyrrolidinyl N atoms show a slight deviation from planarity and none of the three N atoms is involved in any hydrogen bond as an acceptor. In the crystal, pairs of inter­molecular N—H⋯O hydrogen bonds form inversion dimers.

N,N'-Dibenzyl-N''-(2-chloro-acet-yl)-N,N'-dimethyl-phospho-ric triamide

In the title mol­ecule, C₁₈H₂₃ClN₃O₂P, the P atom is bonded in a distorted tetra­hedral environment. The P=O and N—H groups are syn with respect to each other. The angles at the tertiary N atoms confirm their sp² character. In the crystal, pairs of inter­molecular P=O⋯H—N hydrogen bonds form centrosymmetric dimers.