Synthesis and structural study of five new phosphoric triamides: interplay between classical and non-classical intermolecular interactions

Phosphoric triamides are attractive to investigate because of their extensive applications in various fields, especially in medicine. Five new phosphoric triamides with the main parts [N]P(O)[NH]2 and [C(O)NH]P(O)[N]2 have been structurally analyzed by single crystal MoKα/synchrotron-based X-ray diffraction and characterized by spectroscopic methods (FT-IR and 1H, 13C, 31P NMR). Compounds crystallize in orthorhombic (1 with space group Pnma) and monoclinic (2 (P21/a), 3 (C2/c), 4 (P21/n) and 5 (P21/c)) crystal systems. The asymmetric unit of all structures consists of one phosphoric triamide molecule, except for 1 with one half of molecule. X-ray crystallography data reveal that the molecular architectures constructed by classical N—H … O hydrogen bonds are as 1D linear (building the R 2 1 ( 6 ) ${R}\_{2}^{1}(6)$ , C(4) and R 2 2 ( 10 ) / R 2 1 ( 6 ) ${R}\_{2}^{2}(10)/{R}\_{2}^{1}(6)$ motifs, respectively, for 1–3) or dimeric (the R 2 2 ( 8 ) ${R}\_{2}^{2}(8)$ ring motif for 4 and 5). A detailed investigation of the intermolecular interactions using Hirshfeld surface (HS) analysis illustrates that the H … H, O … H/H … O and C … H/H … C contacts for all compounds, and Cl … H/H … Cl and F … H/H … F contacts for 3–5, are the most significant contributors to the crystal packing. Moreover, based on the calculated enrichment ratios (E), the O … H/H … O contacts including the classical N—H … O hydrogen bonds for all structures are considered as favoured contacts.

HMPA-Free Generation of Trialkylsilyllithium Reagents and Its Applications to the Synthesis of Silylboronic Esters

Trialkylsilyllithium species have turned out to be facilely generated by treating hexaalkyldisilanes with methyllithium in the presence of tris(N,N-tetramethylene)phosphoric triamide (TPPA) as an activator, which can be trapped by boron electrophiles to afford silylboronic esters including long-awaited Me3Si–B(pin).

HMPA-Free Generation of Trialkylsilyl Lithium Reagents and Its Application to Synthesis of Silylboronic Esters

Trialkylsilyl lithium species have turned out to be facilely generated by treating hexaalkyl disilanes with methyl lithium in the presence of tris(<i>N,N</i>-tetramethylene)phosphoric triamide (TPPA) as an activator, which can be trapped by boron electrophiles to afford silylboronic esters including long-awaited Me₃Si–B(pin).

HMPA-Free Generation of Trialkylsilyl Lithium Reagents and Its Application to Synthesis of Silylboronic Esters

Trialkylsilyl lithium species have turned out to be facilely generated by treating hexaalkyl disilanes with methyl lithium in the presence of tris(<i>N,N</i>-tetramethylene)phosphoric triamide (TPPA) as an activator, which can be trapped by boron electrophiles to afford silylboronic esters including long-awaited Me₃Si–B(pin).

Structural differences/similarities of diastereotopic groups in three new chiral phosphoramides

The crystal structures of two single-enantiomer amidophosphoesters with an (O)2P(O)(N) skeleton and one single-enantiomer phosphoric triamide with an (N)2P(O)(N) skeleton were studied. The compounds are diphenyl [(R)-(+)-α-4-dimethylbenzylamido]phosphate, (I), and diphenyl [(S)-(−)-α-4-dimethylbenzylamido]phosphate, (II), both C21H22NO3P, and N-(2,6-difluorobenzoyl)-N′,N′′-bis[(R)-(+)-α-ethylbenzyl]phosphoric triamide, C25H28F2N3O2P, (III). The asymmetric units contain two amidophosphoester molecules for (I) and (II), and one phosphoric triamide molecule for (III). In the crystal structures of (I) and (II), molecules are assembled in a similar one-dimensional chiral ribbon architecture, but with almost a mirror-image relationship with respect to each other through N—H...O(P) and C—H...O(P) hydrogen bonds along [010]. In the crystal structure of (III), the chiral tape architecture along [100] is mediated by N—H...O(P) and N—H...O(C) hydrogen bonds, and the tapes are connected into slabs by C—H...O interactions (along the ab plane). The differences/similarities of the two diastereotopic phenoxy groups in (I)/(II) and the two chiral amine fragments in (III) were studied on the grounds of geometry, conformation and contribution to the crystal packing, as well as 1H and 13C signals in a solution NMR study.

Conformational analysis of two new organotin(IV) structures completed with a CSD survey

The conformational flexibilities are studied in two new organotin(IV) complexes, namely, trans-dichloridodimethylbis[N,N′,N′′-tris(2-chlorobenzyl)phosphoric triamide]tin(IV), [Sn(CH3)2(C21H21Cl3N3OP)2Cl2] or Sn(CH3)2Cl2{OP[NHCH2C6H4(2-Cl)]3}2, (I), and bis(dipropylammonium) tetrachloridodimethylstannate(IV), [(CH3CH2CH2)2NH2]2[Sn(CH3)2Cl4], (II), and their analogous structures from the Cambridge Structural Database (CSD). The conformations are considered based on the N—P=O—Sn torsion angles for (I) and the C—C—C—N, C—C—N—C, C—N—C—C and N—C—C—C torsion angles for the two symmetry-independent [CH3CH2CH2NH2CH2CH2CH3]+ cations in (II), and the ±ac±sp±ac (ac = anticlinal and sp = synperiplanar) and ±ap±ap±ap±ap (ap = antiperiplanar) conformations are observed, respectively. In both structures, the four atoms in the corners of the square-planar segment of the octahedral shape around the Sn atom participate in normal hydrogen-bonding interactions as acceptors, which include two O and two Cl atoms for (I), and four Cl atoms for (II). However, the phosphoric triamide ligands block the environment around the Sn atom and limit the hydrogen-bond pattern to form a supramolecular ribbon assembly, while in the presence of small organic cations in (II), a two-dimensional hydrogen-bonded architecture is achieved. The weak interactions π–π, C—H...π and C—Cl...π in (I), and C—H...Cl in (II) do not change the dimensionality of the hydrogen-bond pattern. The 62 CSD structures analogous to (I), i.e. with an SnOPN3 segment (including 83 entries) fall into four categories of conformations based on the N—P=O—Sn torsion angles. The 132 [(CH3CH2CH2)2NH2]+ cations from 85 CSD structures are classified into seven groups based on the torsion angles noted for (II). Most of the CSD structures adopt the same associated conformations noted for (I) and (II). 15 [Sn(CH3)2Cl4]2− anions extracted from the CSD are compared with the structure of (II).

Coordination versus hydrogen bonds in the structures of different tris(pyridin-2-yl)phosphoric triamide derivatives

Tris(pyridin-2-yl)phosphoric triamide, as a metal complex and purely organic pseudopolymorphs, and the role of solvent/hydrate and substituent in the formation of the crystal packing features, along with an improved model of the MOF structure of Cu(ii)O6 are investigated.

Epoxy Resins and their Zinc Composites as Novel Anti-Corrosive Materials for Copper in 3% Sodium Chloride Solution: Experimental and Computational Studies

The evaluation the anticorrosive performance of two macromolecular aromatic epoxy resins (ERs), namely, tetra glycidyl of ethylene dianiline (TGEDA), hexaglycidyl Tris (p-Ethylene Dianiline) Phosphoric Triamide (HGEDPAT), and their polymer composite reinforced with Zinc for copper corrosion in 3% NaCl by means of computational and experimental analyses. Anticorrosive property of the standards and composites was demonstrated using experimental and computational methods. Electrochemical results showed that HGEDAPT cured with methylene dianiline (MDA) showed better protection efficiency with optimum corrosion current density (icorr) value of 2.0 µcm-2 and the polarization resistance (Rp) value of 17,00 kΩ.cm2 than that of TGEDA-MDA having icorr value of 2.4 µcm-2 and the Rp value of 15.24 kΩ.cm2. The anticorrosive effect of TGEDA-MDA and HGEDAPT-MDA was evaluated in the presence of 5% zinc (Zn). Experimental results demonstrate that the presence of 5% of zinc in TGEDA-MDA and HGEDAPT-MDA formulations significantly enhanced their protection ability. The anticorrosive effect of different formulations followed the order: ER1 (TGEDA-MDA) (potentiodynamic polarization (PDP); 90% and electrochemical impedance spectroscopy (EIS) 92%) < ER2 (HGEDAPT-MDA) (PDP; 92% and EIS 93%) < ER3 (TGEDA-MDA-5%Zn) (PDP; 96% and EIS 97%) < ER4 (HGEDAPT-MDA-5%Zn) (PDP; 97% and EIS 98.5%). Density Functional Theory (DFT) study revealed that ER1 and ER2 interact with the metallic surface using donor-acceptor interactions in which electron-rich centers acted as the most favorable sites for the interactions. Molecular dynamics (MD) simulations studies suggest that ER1 and ER2 acquire flat or horizontal orientations, and their orientations on the metallic surface are largely influenced by the presence of zinc. Different experimental and computational studies are in good agreement.