Synthesis and structure of aryl-substituted phospha-alkenes

An improved synthesis of the two triarylsubstituted phospha-alkenes mesityl (diphenylmethylene)phosphine (la) and 2,6dimethylphenyl(diphenylmethylene)phosphine (lb) is described. Of several variants, the preferred route starts with the aryl bromides 4 which are converted to the corresponding Grignard reagents and to the arylphosphonous diamides 7 which with PCl₃, yield arylphosphonous amide chlorides 9 thence phosphinous amides 10 and to the phosphinous chlorides 11 which with DBU eliminate Hcl to furnish the title compounds in 60-85%, yield. The chemical and spectral data of 1a and 1b are discussed; they contain essentially localized P=C bonds and. are stabilized mainly by steric protection. These conclusions are confirmed by HFS-calculations on simple model compounds (17, 16', 18, 19 and 20) which identify the phosphorus lone pair as HOMO and the π-orbital as NHOMO; however, both orbitals are close in energy. Furthermore, the calculations reveal the importance of phosphorus d-orbitals in bonding, and the polarization in the P=C bond (P as positive pole) which had earlier been derived from chemical evidence. Finally, it is shown that interaction of the P=C bond with phenyl groups does not dramatically influence the bonding situation, but substitution by a heteroatom (nitrogen substituted on carbon; 20) does.Of particular interest in the crystal and molecular structure of la are the short P=C bond length (1.692(3)ÅA) and the Mes-P-C bond angle (107.5°); the latter is smaller than expected (and found) for purely sp²-hybridized atoms, but larger than the unsubstituted parent compound HP=CH₂ (16).³ It is also noteworthy that the structure of 1a is essentially unchanged on complexation to metal centres.     

Kadpolysperins A–N,lanostane triterpene acids possessing rich structure types from Kadsura polysperma

Fourteen new lanostane triterpene acids (1–14), and five known analogues (15–19) were isolated from the stems of Kadsura polysperma. Compound 1, with a rearranged tetracyclic skeleton, is an important biogenic precursor of longipedlactone skeleton. Compounds 2–6 are members of 18(13→12)-abeo-lanostane triterpene acids. The structures of new compounds were elucidated by spectroscopic evidence. Selected compounds were evaluated for their in vitro cytotoxicity against human tumor HL-60, SMMC-7721, A-549, MCF-7, and SW-480 cell lines.     

Computational investigation of the structure and antioxidant activity of some pyrazole and pyrazolone derivatives

Pyrazoles and pyrazolones constitute a group of organic compounds that have various medical applications such as antimicrobial, antipyretic, anti-inflammatory, antitumor and antioxidants. Pyrazolones can exist in different isomeric forms (CH, NH, OH) due to keto-enol, lactam-lactim and imine-enamine tautomerism. Determination of the most stable tautomeric form is thus important for understanding their biological roles at the molecular level. We performed a theoretical investigation of the structural and antioxidant properties of three synthetic pyrazolones (1–3), one synthetic pyrazole (4), one natural pyrazole (5) and two engineered hydroxyl derivatives of 1 (7, 8) and of 5 (9, 10) using the density functional theory at the B3LYP/6-311++G(d,p) level of theory in gas phase and in methanol (using the polarizable continuum model). It is found that substituents and solvents may influence the relative stability of pyrazolone isomers and that the CH tautomer is typically the least stable. Vertical ionization potentials, vertical electron affinities and X–H bond dissociation energies (X?=?C, N, O, S) are calculated for the global minimum structures and compared with those of the standard antioxidant flavonoid quercetin (6). Calculations predict that compounds 1 and 5 have antioxidant activity similar to 6 and that their mono and dihydroxyl derivatives (7–10) are more efficient antioxidants. Results also indicate that compounds 1–10 preferably interact with free radicals adopting the H atom transfer rather than the sequential electron transfer proton transfer mechanism. The study gives insight into the structural requirements for the design of highly efficient antioxidants.     

Diphenylantimony(III) diphenylphosphinate and diphenylmonothiophosphinate: synthesis,spectra and crystal structure

Infrared data suggest that in diphenylantimony(III) diphenylphosphinate and diphenylthiophosphinate, Ph₂Sb[OP(X)Ph₂], where X = O (1 or S (2), the ligands are symmetrically bonded, either as chelating or bridging groups, and the presence of the latter has been confirmed by X-ray diffraction. Ph₂SbO₂PPh₂ (1) is orthorhombic, space group P2₁2₁2₁, with a 9.185(4), b 11.075(4), c 21.099(7) Å and Z 4. Ph₂SbOSPPh₂ (2) is monoclinic, space group P2₁/n with, a 9.842(4), b 10.561(4), c 21.182(7) Å, β 93.19(4)° and Z 4. In both compounds diphenylantimony(III) groups are linked into chains by bridging phosphinate or thiophosphinate groups and antimony achieves pseudotrigonal bipyramidal coordination with the two phenyl groups in equatorial positions. The axial positions are occupied by oxygen and sulphur atoms of the ligands. The independent SbO and PO bond lengths in 1 are very similar (2.23, 2.29 and 1.49, 1.51 Å), while in 2 the PO and PS distances, 1.503 and 2.010 Å respectively, also point to symmetrical coordination. Stereochemical activity of the lone pair is considered.     

New fluorochromatouranylates of alkali metals: Synthesis and structure

Four new fluorochromatouranylates, namely, K[UO₂(CrO₄)F] · 1.5H₂O (I), Rb[UO₂(CrO₄)F] · 1.5H₂O (II), Rb[UO₂(CrO₄)F] · 0.5H₂O (III), and Cs[UO₂(CrO₄)F] · 0.5H₂O (IV), have been synthesized, and their crystallographic characteristics have been determined. All the compounds crystallize in monoclinic system, space group P2₁/c, with the unit cell parameters a = 13.1744(5) Å, b = 9.4598(3) Å, c = 13.0710(4) Å, β = 103.746(1)°, Z = 4, R = 0.0235 (I); a = 13.5902(7) Å, b = 9.5022(4) Å, c = 13.2271(6) Å, β = 102.914(2)°, Z = 4, R = 0.0247 (II); a = 24.7724(8) Å, b = 12.6671(4) Å, c = 9.4464(3) Å, β = 97.661(1)°, Z = 8, R = 0.0448 (III); a = 25.725(1) Å, b = 12.8261(5) Å, c = 9.4929(4) β = 97.208(1)°, Z = 8 (IV). The pairs of compounds I and II and compounds III and IV are isostructural. Crystals of compounds I–III have been subjected to complete X-ray diffraction study. It has been established that the structures of compounds I–III are built of [UO₂(CrO₄)F] _n ^n? layers, which are parallel to the (100) plane and linked into a framework by alkali-metal cations located between layers, together with water molecules. The effect of topological and geometric isomerism on the structural features of 34 known uranyl compounds of the AT³M² crystallochemical group, to which the studied compounds I–III also belong, is discussed.     

Synthesis of novel P-stereogenic phenylphosphonamides and their application to Lewis base-catalyzed asymmetric allylation of benzaldehyde

The synthesis of novel P-stereogenic phenylphosphonamides 3 and 11 via an intramolecular nucleophilic substitution of P-stereogenic phosphoramide 8 is described. These compounds were used as chiral Lewis basic catalysts for the asymmetric allylation of benzaldehyde, providing the corresponding homoallylic alcohol derivatives in up to 54% ee.     

The synthesis,X-ray crystal structure and optical properties of novel 1,3,5-triaryl pyrazoline derivatives

A series of novel 1,3,5-triaryl pyrazoline derivatives has been synthesized by the reaction of chalcone and 3-chloro-6-hydrazinylpyridazine in 47–82% yields. The structures of compounds obtained were determined by IR, ¹H NMR and HRMS spectra. Representatively, the spatial structure of compound 3d was determined by using X-ray diffraction analysis. Absorption and fluorescence spectral characteristics of the compounds were investigated in CHCl₃ by UV–vis absorption and emission spectra. The results showed that the absorption maxima of the compounds vary from 332 to 342 nm depending on the group bonded to benzene rings. The maximum emission spectra of compounds in CHCl₃ are dependent on groups in benzene ring in which a strong electron-donating group in benzene ring such as methoxyl group on C3 position of pyrazoline made the emission wavelength of 3e, 3f and 3g red shifted than that of compounds 3b, 3c and 3d with chlorine group. The intensity of absorption and fluorescence was also correlated with substituent on two aryl rings. In addition, the absorption spectra of these compounds change very little with increasing solvent polarity.     

Synthesis and structure of tetra- and triphenylantimony salicylaldoximates

Tetraphenylantimony salicylaldoximate (I) was synthesized by reactions of pentaphenylantimony with salicylaldoxime or triphenylantimony disalicylaldoximate in toluene. Triphenylantimony bis(salicylaldoximate) (II) was synthesized by the reaction between triphenylantimony, hydrogen peroxide, and salicyl- aldoxime. The structures of compounds I and II were determined by X-ray crystallography. The coordination of Sb atoms in I and II is a distorted trigonal bipyramid. For compounds I and II, Sb-C bond lengths are 2.1132(13)?C2.1760(14) ? and 2.1026(15)?C2.112(2) ?, the Sb-O distances are 2.1771(11) ? and 2.0768(11) ?, and the Sb??N intermolecular contacts are equal to 2.945(2) ? and 2.882(2) ?, respectively.     

Crystal and molecular structure of two new Schiff bases: Paeonol-ethylenediamine and paeonol-1,3-propylenediamine

Two new Schiff bases were prepared by the condensation reaction of paeonol with ethylenediamine (for compound 1) and 1,3-propylenediamine (for compound 2). The compounds were studied with single crystal X-ray diffraction method. Compound 1 is monoclinic, space group P2₁/c, a = 10.956(15) Å, b = 6.767(10) Å, c = 12.494(18) Å; β = 104.66(2)°, V = 896(2) ų, Z = 2. Compound 2 is triclinic, space group P-1, a = 6.878(2) Å, b = 12.141(4) Å, c = 12.414(4) Å; α = 101.023(6)°, β = 103.415(6)°, γ = 102.337(6)°, V = 952.8(6) ų, Z = 2. The molecular structures of 1 and 2 are similar; the molecule being centrosymmetric in 1 but asymmetric in 2.     

Electronic structure and conformational equilibria of phenyl-propylcarbocations

Modified CNDO calculations were performed on different conformations of various phenyl propyl cations and related compounds. Molecular energies and electronic structures are presented and discussed. A substituted secondary benzyl cation, the 1-phenyl-1-propyl carbocation (12) is found to be the most stable isomer. The open chain 1-phenyl-2-propyl carbocation (11b) has a lower energy than the propylene benzenium cation (11d). In contrary, previous calculations of 2-phenyl-1-ethyl cation lead to the result that in this case the ethylene benzenium cation is the most stable structure. Rotational barriers for different substituted 1-propyl and 2-propyl cations were calculated. The results are explained by hyperconjugative stabilization.     

Structural and fluorescence properties of phenolphthalein bridged cyclotriphosphazatrienes

This study dealt with the reactions of hexachlorocyclotriphosphazatriene, N₃P₃Cl₆ (trimer) (1) with phenolphthalein (2) to give the phenolphthalein bridged compounds 3, 4 and 5. The phenolphthalein bridged cyclotriphosphazatriene derivatives are reported for the first time. The new compounds (3–5) are characterized by elemental analysis, mass spectrometry, UV–vis, FT-IR, ¹H, ³¹P NMR and fluorescence spectroscopy. The more bridged phenolphthalein groups show the higher intensity of the absorption bands in the UV–vis spectra. Fluorescence spectrum of compound 3 shows a small band in the lower spectral range, while the spectra of compounds 4 and 5 show more intense and a band in higher spectral range.     

Synthesis,crystal structure and optical properties of A3Zr2P5S18 (A=Rb,Cs): the first quaternary zirconium thiophosphates

The first quaternary zirconium thiophosphates Rb₃Zr₂P₅S₁₈ (1) and Cs₃Zr₂P₅S₁₈ (2) were synthesized by reacting ZrS₂ with an in situ formed melt of A₂S₃ (A=Rb, Cs), P₂S₅ and S. The compounds are isostructural and crystallize in the monoclinic space group Cc with Z=4. Compound 1 has cell parameters a=9.248(2) Å, b=9.860(2) Å, c=33.622(7) Å and β=94.73(3)° and compound 2 a=9.288(2) Å, b=9.956(2) Å, c=34.061(7) Å and β=94.26(3)°. The structures are composed of a two-dimensional anionic layer [Zr₂P₅S₁₈]³⁻ and intervening alkali cations. Each of the two independent Zr atoms is surrounded by seven S atoms yielding a distorted pentagonal bipyramid. The ZrS₇ polyhedra are interconnected into the final layered anion by [P₂S₇] groups which act in an unusual edge- and corner-sharing mode and by edge-sharing [PS₄] tetrahedra. Compound 2 was characterized with MIR and UV/vis diffuse reflectance spectroscopy.     

Cabralea eichleriana dc. (meliaceae)—I structure and stereochemistry of wood extractives

From Cabralea eichleriana DC. (Meliaceae) nine compounds having a dammarane skeleton have been isolated and identified. They are cabraleone 2, ocotillone 3, cabraleadiol 4a, cabralealactone 5, cabraleahydroxylactone 6a, eichlerianic acid 7a, shoreic acid 8a, dammarenolic acid 9a and eichlerialactone 10a. The only limonoid present is fissinolide1. Compounds 7a and 10a are hereby reported for the first time as occurring in Nature. Configurations of ocotillone and cabraleone are revised and have been assigned 20S, 24S and 20S, 24R respectively.     

Synthesis, crystal structure and photoluminescence of 2,6-dimethylanthracene and its pseudo-triptycene derivatives

A simple one-step synthesis of 2,6-dimethylanthracene, 1, in high yield is reported utilizing the easily accessible benzyl alcohol as the starting material. Based on 2,6-dimethylanthracene, two pseudo-triptycene compounds, cis-2,6-dimethyl-9,10-dihydroanthracene-9,10-endo-α,β-succinic anhydride, 2, and cis-2,6-dimethyl-9,10-dihydroanthracene-9,10-endo-α,β-succinyl amine, 3, are firstly synthesized in high yield and they are characterized by single crystal X-ray diffraction. Compound 2 crystallizes in triclinic space group and compound 3 crystallizes in monoclinic P2₁/c space group. Both compound 2 and 3 exhibit cis-configurations and endo-conformations. Compound 1 exhibits very intense photoluminescence property due to the delocalized electron in the whole molecule, whereas fluorescence quench happens to some extents due to the destruction of the conjugated structure in compound 2.     

Synthesis and structure of diethylenetriammonium tetrachloroaurates(III)

The (DienH₃)[AuCl₄]₃ · H₂O (I) and (DienH₃)₂[AuCl₄]Cl₅ (II) compounds were obtained by the reaction of HAuCl₄ with diethylenetriamine trihydrochloride (DienH₃Cl₃) in hydrochloric acid. The compounds were characterized by elemental analysis, X-ray diffraction, thermogravimetry, and IR spectroscopy. Crystals of I and II are monoclinic with space group P2₁/n. For I, a = 12.2314(3) Å, b = 14.6077(5) Å, c = 13.2680(5) Å, β = 106.7350(10)°, V = 2270.22(13) ų, Z = 8. For II, a = 6.62990(10) Å, b = 17.9026(5) Å, c = 10.3661(3) Å, β = 101.9230(10)°, V = 1203.83(5) ų, Z = 2. Both structures are ionic. The gold atoms in I and II have a 4 + 2 coordination environment. The Au-Cl bond lengths are within 2.276–2.294 Å, and the axial Au…Cl contacts are within 3.315–3.405 Å. The diethylenetriammonium cation in I and II has different conformations.     

Two non-centrosymmetric cubic seleno-germanates related to CsCl-type structure: Synthesis, structure, magnetic and optical properties

Two related non-centrosymmetric, cubic, quaternary chalcogenides, containing europium have been synthesized employing the molten flux method and by the reaction of europium halides with the ternary seleno-germanate, Na₆Ge₂Se₆. The reactions of Eu, Ge and Se were accomplished in a molten Na₂Se₂ flux at 800 °C for 150 h in an evacuated fused silica ampoule and yielded Na₂EuGeSe₄ (I). Similarly, Na_0.75Eu_1.625GeSe₄ (II), could be synthesized at slightly lower temperature (750 °C) with a different starting ratio of Eu, Ge, Se and Na₂Se₂. A reaction between EuCl₃ and Na₆Ge₂Se₆ in 1:2 ratio at 650 °C for 96 h in an evacuated fused silica ampoule yielded Na₂EuGeSe₄ (I), while the reaction between EuI₂ and Na₆Ge₂Se₆ in 1:1 ratio under similar conditions yielded Na_0.75Eu_1.625GeSe₄ (II). Crystal data for these compounds are as follows: I, cubic, space group I4¯3m (no. 217), a=7.3466(3), Z=2; II, cubic, space group I4¯3d (no. 220), a=14.7065(8), Z=16. The crystal structures of I and II are closely related and can be compared to a CsCl-type and its ordered superstructure, respectively. These compounds are semiconductors with optical band gaps around 2 eV. The temperature dependence of the magnetic susceptibility indicated that both compounds are paramagnetic with μ_eff.=7.6 and 7.73 μ_B, for I and II, respectively, close to the theoretical value of 7.94 μ_B for Eu²⁺. Raman spectroscopic characterization of the compounds is also reported.     

A new molecular building blocks: Synthesis,crystal structure,magnetic and spectroscopic properties of Cu(II) and Ni(II) macrocyclic complexes

New higly unsaturated macrocyclic building blocks [CuLSCN]·ClO₄ (1) (L = N-dl-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) and [NiL(SCN)₂] (2) (L = N-dl-5,12-dimethyl-7,14-diisopropyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) were synthesized and the crystal structures of both compounds were determined. Both complexes crystallizes in monoclinic, space group P2₁/n (1) and P2₁/c (2). Their magnetic properties were studied over the temperature range 1.8–300 K using a Quantum Design SQUID magnetometer (MPMSXL-5-type). The results indicate that both compounds behave as weakly interacting paramagnetic centers in the crystal lattice. The effects of hydrogen bond mediating the magnetic exchange interactions on the spin density have been evidenced by DFT calculations. The NIR–Vis–UV diffuse-reflectance electronic spectra confirm the square pyramidal and octahedral geometry around Cu²⁺ and Ni²⁺ metal ions.     

Cryptates—XI: Complexes macrobicycliques,formation, structure,proprietes

The macrobicyclic compounds 1–7 form inclusion complexes with alkali and alkaline-earth metal cations. In these complexes, termed cryptates, the metal cation is contained in the intramolecular cavity of the bicyclic system. The formation, the physical and spectroscopic properties and the structure of these complexes are described and discussed in detail. The formation of some complexes with the macrocyclic ligands 8a–e is also reported.     

The structure determination of two new acylphloroglucinols from Myrtus communis L.

Structures for two new acylpholorglucinols, myrtucommulone A (1) and myrtucommulone B (2) have been deduced from a detailed study of the NMR, IR and mass spectra of these substances, and their simple derivatives and degradation products. The compounds contain phloroglucinol and syncarpic acid (1,1,3,3, tetramethyl-cyclohexa-2,4,6-trione) residues, and are closely related chemically to fern constituents such as filixic acid, as well as to kosins and uliginosins isolated from higher plants. Compounds 1 and 2 are unique in having an isobutyl bridge connecting the rings. Compound 1 exhibits strong antibacterial activity against gram positive bacteria.     

Phosphorus heterocycle synthesis by RPX2 · ALX3 addition to [1,n]dienes—IX : The synthesis and structure of several oxaphosphabicyclic compounds

Several oxaphosphabicyclic compounds were synthesized by the reaction of methyl dihalophosphane under various conditions with 1,6-diketones and βγ-unsaturated ketones. The structure of one of the new compounds (11) was established by X-ray diffraction analysis. The ¹H- and ¹³C-NMR spectra of the new compounds, which, except for 11, served for their structure elucidation, are discussed.