Polarity and Conformations of Phosphazacompounds in Solution

Abstract

A series of iminophosphoranes o-X-C₆H₄-N=PPh₃, where X=H(I),Me (II),Et (III),OMe(IV),OEt(V) were investigated by means of dipole moments method. Because of an orientation of aromatic fragment determines intramolecular interactions in the system (benzene ring - double N=P bond), the problem of internal rotation of N-C_ar bond is important. DM (exp.) of molecules (I-V), determined in dioxane are 4.30(I), 4.34(II), 4.53(III), 4.75(IV), 4.79 D(V), respectively.     

The Reactions of Hydrophosphoranes with Cyclopentadienones

Abstract

Phencyclone reacts with trialkylphosphites regiospecifically to give the adduct (I) containing the bond phosphorus-C² atom of cyclone. In the presence of carboxylic acids the reaction products were phosphate (II), β-ketophosphonate (III) and dihydrophencyclone (IV).     

Syntheses,crystal structures and magnetic properties of two cyano-bridged copper(I)–copper(II) mixed-valence complexes

Two cyano-bridged copper(II)–copper(I) mixed-valence assemblies, Cu(EAM)₂[Cu(CN)₂]₂ 1 (EAM?=?ethanolamine) and Cu(DETA)[Cu(CN)₂]₂·0.5H₂O 2 (DETA?=?diethylenetriamine), have been prepared and structurally and magnetically characterized. IR spectra indicate the presence of bridging cyano groups in both 1 and 2, confirmed by structure analyses; Cu(I)–CN–Cu(II), Cu(I)–CN–Cu(I) and Cu(I)–Cu(I) metal bond linkages are evident. In the lattice, a 3D network is formed by two [Cu(CN)₂]?^? units and one [Cu(EAM)₂]²⁺unit for 1. Variable temperature magnetic susceptibilities, measured in the 5–300?K range, indicate weak antiferromagnetic exchange interactions in complex 1.     

The Nature of the Phosphorus Tellurium Bond in Tellurophosphoranes and their Derivatives

Abstract

Tellurophosphoranes, which may be considered as phosphane chalkogenides (I) or as phosphane stabilized tellurium atoms (II), form coordination compounds III and IV. The nature of both the phosphorus tellurium and the phosphorus element bond is discussed from chemical and spectroscopic properties.     

Synthesis of Naturally Occurring Helminthic Phosphodiesters and Related Analogues

Abstract

Our preliminary findings in the use of 1,3,2-oxazaphospholidin-2-ones (III) as useful synthons in the synthesis of naturally occurring helminthic (worm) phosphodiesters [i.e. Opheline(II, R=Me) and serine ethanolamine phosphate (I, R=NH₂(CO₂H)CHCH₂,R′=H)] and of related compounds are reported. The 1,3,2-oxazaphospholidin-2-ones can be synthesised by routes A and B; once formed these can be ring-opened by acid treatment which causes exclusive N-P bond fission yielding the phosphodiesters (I). Guanidinated phosphodiesters (II) have been made by reacting the corresponding phosphodiesters (I,R′=H) with O-methylisourea.     

Dynamic Stereochemistry of Phosphaalkenes

Abstract

The degenerative Z,E-isomerization at the P=C bond in phos-phaalkenes I and II has been studied by dynamic NMR spectroscopy. The complete bandshape analysis was used to evaluate the activation parameters for intramolecular dynamic process.     

Rhodium-catalyzed synthesis of 1-alkynylphosphine oxides from 1-alkynes and tetraphenylbiphosphine

A rhodium complex RhH(PPh₃)₄ catalyzes the C-P bond forming reaction of 1-alkynes and tetraphenylbiphosphine in the presence of 2,4-dimethylnitrobenzene giving 1-alkynylphosphines and its oxides.     

ELECTRON SPIN RESONANCE OR Pd(I). III: The Nature of the Metal-ligand Bonds in Square Planar Complexes of Palladium(I)

Abstract

ESR spectra for a variety of palladium(I) complexes produced in the powders and the frozen solutions of palladium(II) complexes by γ -ray irradiation have been interpreted in terms of the nature of the metal-ligand bonds. It has been found that the covalency for the palladium-ligand σ-bond increases in the order of Pd[sbnd]O, Pd[sbnd]Cl < Pd[sbnd]N < Pd[sbnd]S, Pd[sbnd]C, and that the nature of the metal-ligand bond in palladium(I) complexes is very similar to that in copper(II) complexes. The ratio of the magnitude of the ligand field splitting for palladium(I) complex to that for the copper(II) complex with the same ligand has been estimated from the comparison of their g values.     

A selective chemosensor for detection of Ag(I) and Cu(I) based on an acenaphthoquinone derivative and its complexes

A new Schiff base, acenaphthoquinone bis(diphenylmethlenehydrazone) (L), was synthesized and employed as a chemosensor for detecting Ag(I) and Cu(I). Experimental results showed that the chemosensor exhibited high selectivity and sensitivity. The sensitivity of the chemosensor for Ag(I) or Cu(I) was not affected by other metal ions, such as Ni(II), Nd(III), Zn(II), Fe(III), Cu(II), Na(I), La(III), K(I), and Co(II). Complexes 1 and 2 were synthesized by coordination of L with Ag(I) and Cu(I), respectively. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. They had the same space group P2₁/c. Based on theoretical calculation, mechanism of the chemosensor detecting Ag(I) and Cu(I) was suggested.     

HYDROBORATION OF UNSATURATED AMINES X. HYDROBORATION-HALOGENATION OF ALLYL PHOSPHORAMIDATES ROUTE TO γ-HALOGENOPROPYL PHOSPHORAMIDATES AND γ-HALOGENATED AMINES

Abstract

This paper describes the synthesis of γ-halogenopropyl phosphoramidates I by hydroboration-halogenation reaction of N-phosphorylated allylamines II (phosphoramidates and phosphoramides). Only the use of allyl phosphoramidates leads to a good regioselectivity of the addition of boron atom on the terminal carbon atom of the allyl structure (compounds III).

The absence of N→B complex formation permits a good reactivity of the trialkylboranes III and IV. The breaking of the P[sbnd]N bond, in acidic medium of the compounds I gives corresponding γ-halogenated amines V.     

Metal-Loaded Sorbents for Selective On-Line Sample Handling and Trace Enrichment in Liquid Chromatography

Abstract

Three different commercially available stationary phases containing a thiol, an 8-hydroxyquinoline (oxine), and a 2-amino-1-cyclopentene-1-dithiocarboxylic acid (ACDA) functional group, were loaded with mercury (Hg(II)), platinum (Pt(IV)) and silver (Ag(I)) ions. The phases were packed in small precolumns and evaluated for their potential towards the selective on-line sample handling and trace enrichment of three model systems in liquid chromatography. The thiol 2-mercaptobenzimidazole was used to study trace enrichment on Hg(II)-loaded phases; the herbicide buturon, which contains an ethynic bond, was selected to study trace enrichment on Ag(I)-loaded phases. The on-line filter effect of Pt(IV)-loaded phases was investigated with 4-chloroaniline as a model compound.

The results indicate that the Hg(II)-ACDA phase should be preferred for the trace enrichment of thiols, a Pt(IV)-ACDA or a Pt(IV)-thiol phase for the anilines and the Ag(I)-oxine phase for the trace enrichment of ethynic compounds.

As environmental application, the selective on-line trace enrichment of buturon from river water samples, on a precolumn packed with Ag(I)-oxine, is shown.     

Synthesis and Solid-State Molecular Structure of Bi(silacyclohexyls) C5H10SiX-XSiC5H10 with X = H,PH, F,CL, BR,and I

The synthesis and purification of novel bi(silacyclohexyls) C₅H₁₀SiX-XSiC₅H₁₀ with X = H (1), Ph (2), F (3), Cl (4), Br (5), and I (6), which are composed of two silacyclohexyl rings connected by a silicon–silicon single bond, is described. Molecular structures for 2, 4, 5, and 6 were determined employing X-ray crystallography. Surprisingly, the SiSi bond lengths increase in the order I < Br < Cl, contrary to what is observed for methylated disilanes Me₂XSiSiXMe₂. The bond lengthening can be traced back to 1, 3 nonbonded interactions between the halogen atoms and the axial hydrogen atoms in the SiC₅ ring, which also cause a decrease of the SiSiX bond angles with increasing size of the halogen atom. Both rings substitute each other in the equatorial position for 4, 5, and 6, but in the axial position for 2.     

An X‐ray crystallographic and density functional theory study of (3Z)‐4‐(5‐ethylsulfonyl‐2‐hydroxyanilino)pent‐3‐en‐2‐one and (3Z)‐4‐(5‐tert‐butyl‐2‐hydroxyanilino)pent‐3‐en‐2‐one

The Schiff base enaminones (3Z)‐4‐(5‐ethylsulfonyl‐2‐hydroxyanilino)pent‐3‐en‐2‐one, C₁₃H₁₇NO₄S, (I), and (3Z)‐4‐(5‐tert‐butyl‐2‐hydroxyanilino)pent‐3‐en‐2‐one, C₁₅H₂₁NO₂, (II), were studied by X‐ray crystallography and density functional theory (DFT). Although the keto tautomer of these compounds is dominant, the O=C—C=C—N bond lengths are consistent with some electron delocalization and partial enol character. Both (I) and (II) are nonplanar, with the amino–phenol group canted relative to the rest of the molecule; the twist about the N(enamine)—C(aryl) bond leads to dihedral angles of 40.5 (2) and −116.7 (1)° for (I) and (II), respectively. Compound (I) has a bifurcated intramolecular hydrogen bond between the N—H group and the flanking carbonyl and hydroxy O atoms, as well as an intermolecular hydrogen bond, leading to an infinite one‐dimensional hydrogen‐bonded chain. Compound (II) has one intramolecular hydrogen bond and one intermolecular C=O...H—O hydrogen bond, and consequently also forms a one‐dimensional hydrogen‐bonded chain. The DFT‐calculated structures [in vacuo, B3LYP/6‐311G(d,p) level] for the keto tautomers compare favourably with the X‐ray crystal structures of (I) and (II), confirming the dominance of the keto tautomer. The simulations indicate that the keto tautomers are 20.55 and 18.86 kJ mol⁻¹ lower in energy than the enol tautomers for (I) and (II), respectively.     

Molecular orbital study of some heterocycles containing nitrogen and sulphur

A systematic study of 1, 2, 5-Thiadiazole (I), 2, 1, 3-Benzothiadiazole (II) and the recently synthesised Naphtho[2, 3-c]-1, 2, 5 thiadiazole (III) has been made using the Hückel molecular orbital theory (HMO). Stability and reactivity of these molecules as predicted by HMO calculations are in agreement with experimental observations. For (I) and (II) bond lengths are known and excellent agreement with theory has been shown. Spin densities calculated for the radical anion of (II) are in good agreement with experimental data. Bond lengths in (III) and its reactivity as well as the spin densities for its radical anion are predicted.

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Zusammenfassung Es wurde eine systematische HMO-Studie von 1, 2, 5-Thiadiazol (I), 2, 1, 3-Benzothiadiazol (II) und dem kürzlich synthetisierten Naphto-[2, 3-c]-1, 2, 5-thiadiazol (III) durchgeführt. Die HMO -Berechnung der Stabilität und Reaktivität ist in Übereinstimmung mit den experimentellen Ergebnissen. Theoretische Bindungslängen für (I) und (II) und Spindichten für (II) sind ebenfalls in Übereinstimmung mit den Experimenten, Bindungslängen und Spindichten für (III) werden vorausgesagt.

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Résumé Utilisant la méthode des orbitales moléculaires de Hückel (HMO) nous avons étudié systématiquement les 1, 2, 5-thiadiazole (I), 2, 1, 3-benzothiadiazole (II) et le naphto [2, 3-c] 1, 2, 5 thiadiazole (III) récemment synthétisé. La stabilité et la réactivité de ces molécules, telles que la théorie les prédit, sont en bon accord avec les données expérimentales. Les longueurs des liaisons de (I) et (II) sont connues et sont en bon accord avec la théorie. Les densités de spin calculées pour l'anion radicalaire de (II) sont en bon accord avec l'expérience. On prédit les longueurs de liaison et la réactivité de (III) ainsi que les densités de spin de son anion radicalaire.

     

Cytotoxicity activity,in silico molecular docking,protein- and DNA-binding study of a new Ni(II) Schiff base complex

Abstract

One new nickel(II) complex, [Ni(L)] (1), was synthesized from the Schiff base ligand derived from pyrrole-2-carboxaldehyde and 1,3-diaminopropane. Complex 1 was characterized by elemental analysis, IR, UV-Vis and ESI mass spectroscopy, cyclic voltammetry, and single-crystal X-ray structure analysis. Crystallographic results show that two Ni(II) monomeric moieties are present with similar structural features but with slightly different bond lengths and bond angles. The geometry around the Ni(II) center is distorted square planar. DNA-binding properties of complex 1 were well explored by employing UV-Vis and fluorescence spectral methods, cyclic voltammetry, and by viscosity measurements. Similarly the protein-binding study was studied by multispectroscopic techniques using both BSA and HSA. The cytotoxicity study of the compound has also been evaluated. Notably, the in vitro cytotoxicity of complex 1 on two cancer cell lines (AGS and A549) demonstrates that complex 1 has very good anticancer activity. MTT assay, cell-cycle analysis, and annexin-V assay have been performed to know the extent of effect of complex 1 as anticancer agent. Further, in silico molecular docking study revealed that the nickel(II) complex fits into the minor groove of duplex DNA by hydrophobic interaction with functional groups of B-DNA.     

Synthesis and NMR Characterization of Two Novel Anthracene-Derived BIS-Aminophosphonates. Basic Hydrolysis of Some Aminophosphonate Derivatives

Abstract

The synthesis of two novel bis-aminophosphonates bearing anthracene rings – bis[N- methyl(diethoxyphosphonyl)-1-(9-anthryl)]benzidine (3) and 4,4′-bis[N-methyl(diethoxy-phosphonyl)-1-(9-anthryl)]diaminodiphenylmethane (4) – via the Kabachnik–Fields reaction is reported. The compounds have been characterized by elemental analysis, TLC, IR, NMR (¹H, ¹³C, ³¹P) and fluorescent spectra. The reaction leads to a mixture of the two possible forms (meso and racemic), with predominant formation of one of the diastereomers. The recrystallized compounds 3 and 4 consist of only one diastereomer. A racemization at the chiral centers and a cleavage of the C-P bond are observed in the alkaline hydrolysis of the new compound 4 and three previously described aminophosphonate derivatives 5–7.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Efficient one-pot synthesis of β-hydroxyphosphonates: regioselective nucleophilic ring opening reaction of epoxides with triethyl phosphite catalyzed by Al(OTf)3

A variety of β-hydroxyphosphonates were produced in high yields by ring opening reaction of different types of epoxides with di/trialkyl phosphite esters catalyzed by Al(OTf)₃. The reactions proceeded with complete chemo- and regioselectivity to give the title compounds. This method is new, simple and efficient for the one-pot synthesis of β-hydroxyphosphonates via direct C-P bond formation.     

FCl:PCX complexes: old and new types of halogen bonds

MP2/aug'-cc-pVTZ calculations have been performed to investigate the halogen-bonded complexes FCl:PCX, for X = NC, CN, F, H, CCH, CCF, CH(3), Li, and Na. Although stable complexes with a F-Cl···P halogen bond exist that form through the lone pair at P (configuration I), except for FCl:PCCN, the more stable complexes are those in which FCl interacts with the C≡P triple bond through a perturbed π system (configuration II). In complexes I, the nature of the halogen bond changes from traditional to chlorine-shared and the interaction energies increase, as the electron-donating ability of X increases. The anionic complex FCl:PC(-) has a chlorine-transferred halogen bond. SAPT analyses indicate that configuration I complexes with traditional halogen bonds are stabilized primarily by the dispersion interaction. The electrostatic interaction is the most important for configuration I complexes with chlorine-shared halogen bonds and for configuration II complexes except for FCl:PCNa for which the induction term is most important. The F-Cl stretching frequency is red-shifted upon complexation. EOM-CCSD/(qzp,qz2p) spin-spin coupling constants have been obtained for all FCl:PCX complexes with configuration I. (1)J(F-Cl) decreases upon complexation. (2X)J(F-P) values are quadratically dependent upon the F-P distance and are very sensitive to halogen-bond type. (1X)J(Cl-P) tends to increase as the Cl-P distance decreases but then decreases dramatically in the chlorine-transferred complex FCl:PC(-) as the Cl-P interaction approaches that of a covalent Cl-P bond. Values of (1)J(F-Cl) for configuration II are reduced relative to configuration I, reflecting the longer F-Cl distances in II compared to those of the neutral complexes of I. Although the F-P and Cl-P distances in configuration II complexes are shorter than these distances in the corresponding configuration I complexes, (2X)J(F-P) and (1X)J(Cl-P) values are significantly reduced, indicating that coupling through the perturbed C-P π bond is less efficient. The nature of F-P coupling for configuration II is also significantly different, as evidenced by the relative importance of PSO, FC, and SD components.     

Influence of metal complex formation on the antimicrobial activity of nifuroxazide: spectroscopic,electrochemical, and DFT studies

[M(HL)₂] complexes (M = Co(II) (1), Ni(II) (2), and Cu(II) (3); H₂L = 4-hydroxybenzoic[(5-nitro-2-furanyl)methylene]hydrazide acid, nifuroxazide) were synthesized, characterized (by elemental analysis, TG, IR, UV–vis., EPR, magnetic, and conductance measurements) and tested for their antimicrobial activities. H₂L is a mono-negative bidentate ligand via hydrazone N and C–O^? forming intermediate complexes between tetrahedral and square-planar geometries (“flattened” tetrahedron, D_2d symmetry) for 1 and 2, as well as square-planar for Cu(II) complex 3. Natural bond orbital analysis revealed that the interaction of oxygen with metal ion is the main factor which determines the stability of 1–3 as the binding energy decreases with an increase in the M–O bond length. Time-dependent density functional theory calculations were carried out to understand the electronic transitions in related experimental observations. The reduction potential values of the nitro group are affected by the metal center. Ni(II) complex 2 displayed the highest activity among the tested complexes against Escherichia coli with a MIC₅₀ value of 0.098 μmol mL^?1 compared with 0.131 (1) and 0.117 μmol mL^?1 (3).     

Synthesis and Biological Activities of Phosphonothrixin

A novel herbicidal compound phosphonothrixin possessing a C-P bond, was isolated from the fermentation broth of Saccharothrix sp. ST-888. The biological activity against various weeds and total synthesis of phosphonothrixin are described herein.