Polychelates Based on Magnesium, Aluminum, Iron, Zirconium, and Vanadyl Acetylacetonates - Synthesis, Structure and Properties

The formation of polymeric acetylacetonates of magnesium, aluminum, iron, zirconium, and vanadyl under conditions of mechanochemical activation with subsequent condensation in boiling toluene has been investigated. The obtained compounds have been studied by the methods of gel chromatography, X-ray diffractometry, and positron annihilation and IR spectroscopy. Aluminum chelates have been studied by means of NMR spectroscopy. It has been demonstrated that the mechanochemical activation with subsequent boiling in toluene results in the formation of polymeric chelates, mostly those of iron, zirconium and, to a smaller degree, chelates of aluminum, magnesium, and vanadyl. The molecular weight of soluble high-molecular fractions is in the range 3000–5000 Da. The layered polymer structure has been revealed. Cross-section areas of polymer chains and volumes of coherent scattering regions have been calculated from the diffractometry data. The morphology of polymers consisting of spherical particles of sizes in the range 100–700 nm has been investigated. Based on the data of positron annihilation spectroscopy (PAS), density, and nitrogen low-temperature adsorption, the dependence of the chelate stability on the specific polarizing potential has been determined. A fractal structure of solid-state polychelates has been revealed.

Functional Polysilanes and their Optical, Chiroptical and Photoluminescence Properties

‘Polysilanes’ is an important class of inorganic polymers having Si-Si σ-conjugation along the backbone. They exhibit extraordinary electronic and photophysical properties and find suitable optoelectronics applications. They are typically synthesized by Wurtz coupling reaction of dichlorodialkylsilane or dichlorodiphenylsilane or dichloroalkylphenylsilane and their combinations under drastic reaction conditions by using sodium dispersion in boiling toluene. In such a drastic condition, no functional groups sustain with polysilane polymer. In order to achieve such functional materials, researchers have been interested in synthesizing functional polysilane with a different functional group like a chiral group, azobenzene containing chromophore and other heteroatoms in their main chain or side chain. Therefore, it is a very challenging task to synthesize polysilanes having effective functionality integrated with their structures. However, the modern technological demand of materials leads to efforts to obtain polymers having functional and multifunctional activity in a single material. In this review article, we cover the synthesis of polysilane with functional activity via pre-polymerization and post-polymerization with a functional group.

Regioselective Synthesis of 2-Acylbutadienes from β,γ-Unsaturated Ketones

2-Acylbuta-1,3-dienes have been synthesized regioselectively from aromatic and heteroaromatic β,γ-unsaturated ketones (readily accessible via base-catalyzed addition of ketones to acetylenes) and aldehydes. The reaction smoothly proceeds with piperidine (10 mol%)/acetic acid (10 mol%) catalytic pair in boiling toluene to provide synthetically attractive polyconjugated electron-deficient dienes in up to 94% yield.

Synthesis of New Hyperbranched Phosphorus-Containing Polyesters Starting from Boltorn H20

Upon gentle treatment with SOCl2, hyperbranched polyester Boltorn H20 afforded a mixture of terminal polychlorides. The latter react with an excess of triphenylphosphine in boiling toluene or with pyridine to give a mixture of polyesters with terminal triphenylphosphonium and pyridinium fragments, respectively.

Synthesis and Pharmacological Evaluation of a Novel Series of Cyclopentenone Derivatives

A novel series of cyclopent-2-enone derivatives have been synthesised by the reaction of 4-hydroxy-3,4-diphenylcyclopent-2-enone, cyclic secondary amines, phosphorus reagents, hexamethylphosphoramide and Lawesson's reagent in boiling toluene/THF. The chemical structures of new compounds were identified by 1H NMR, 13C NMR, 31P NMR and mass spectra. Furthermore, the structure of one of the synthesised compounds has been confirmed using single crystal X-ray diffraction. The pharmacological evaluation results of antilung and anticolon carcinoma cell line properties for the products are discussed.

Modified Synthesis of 2-Ethoxycarbonyl-3,4-Diethyl-Pyrrole and the Corresponding Octaethylporphyrin

In the synthesis of 2-ethoxycarbonyl-3, 4-diethyl-pyrrole (1) by the Barton-Zard reaction of 4-acetoxy-3-nitrohexane (1b) with ethyl isocyanoacetate, the organic base 1, 8-diazabicyclo [5.4.0] undec-7-ene (DBU) and the solvent tetrahydrofuran (THF) were replaced with K2CO3 and ethanol, respectively. Moreover, the preparation of the intermediate 1b from 1a by acetylation reaction was carried out by employing acetyl chloride in boiling toluene solution instead of acetic anhydride and the catalyst concentrated sulfuric acid. After treatment of 1 with excess LiAlH4 at low temperature, the crude product 1c (α-hydroxymethyl-3, 4-diethyl-pyrrole) was immediately reacted via a tetramerization in the presence of the catalyst BF3.OEt2 in crude CHCl3,followed by oxidation of 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) to provide the corresponding octaethylporphyrin 2. The results indicate that using BF3.OEt2 as catalyst instead of p-toluenesulphonic acid (p-TsOH)in the synthesis of 2 from 1c can obviously increase the yield of product 2 up to 80% from 69%.

SYNTHESIS OF SOME FLAVONES AND 4-THIOFLAVONES AS POTENT ANTIBACTERIAL AGENTS

A series of flavones and thioflavones were synthesized via the chalcone pathway, in which 2'-hydroxyacetophenone is condensed with benzaldehyde derivatives in the medium of potassium hydroxide - methanol at room temperature. The obtained chalcones were treated by iodine in refluxed dimethyl sulfoxide turning into the corresponding flavones. Reaction of flavones and Lawesson's reagent in boiling toluene gave the 4-thioflavones with high yields from 53-76%. All the synthetic compounds were purified by column chromatography and recorded their UV, IR and 'H-NMR spectra.

Von Ketazinen zu 1,2-Diaza-3-phospha-cyclopent-5-enen, -penta-3,5-dienen, 1,5-Diaza-2,6-diphospha-bicyclo[3.3.0]octa-3,7-dien und einem Cyclohexaphosphan / From Ketazines to 1,2-Diaza-3-phospha-cyclopent-5-enes, -penta-3,5-dienes, 1,5-Diaza-2,6-diphospha-bicyclo[3.3.0]octa-3,7-dien, and Cyclohexaphosphane

The dilithium salt of di(tert-butyl-methyl)ketazine 1 reacts with the bimolar amount of ClSiMe3 to give the di(tert-butyl-trimethylsilylmethylen)ketazine, 2. In the reaction of lithiated 2 and F2PN(iPr)2 the 1,2-diaza-3-phosphacyclopent-5-ene (3) is formed. The dichlorophosphanes Cl2PC6H5 and Cl2PCMe3 react with 1 in boiling toluene to give the 1,2-diaza-3-phosphacyclopentenes 4 and 5. The oxygen of the air oxidizes 5 to the 1,2-diaza-3-phosphacyclopent-5-ene 6. Equivalent amounts of H2O cleave the ring skeleton of 5, the tert-butyl-methyl-(tert-butyl-(tert-butylphosphino)methylketazine 7 being formed. The 1,2-diaza-3-phosphacyclopenta-3,5-diene 8 and the 1,5-diaza-2,6-diphospha- bicyclo[3.3.0]octa-3,7-diene 9 are the reaction products of 1 and PCl3 in toluene. 1 forms with HCl the hydrochloride 10. The 5-tert-butyl-1,2-diaza-3-phospha-cyclopenta-3,5-diene 11 is isolated from the reaction of 9 and MeLi. 11 is also obtained from PCl3 and tert-butyl-methyl-hydrazone in good yields. The cyclohexaphosphane 12 was formed in the reaction of 9 with Na/K alloy. The results of the crystal structure analyses of 2, 3, 6, 10, and 12 are reported.

Preparation, spectroscopic characterization, and deprotonation reactions of Si(NHR)4 (R = i-Pr, t-Bu, p-tolyl) — EPR identification of persistent radicals formed by oxidation of polyimidosilicates

Treatment of Cl2Si(NH-t-Bu)2 (6a) with t-BuNH2 in boiling toluene yields trisamino(chloro)silane ClSi(NH-t-Bu)3 (7); formation of the tetraaminosilane Si(NH-t-Bu)4 is not observed. The reaction of SiCl4 with 4 equiv. of LiNHR produces the corresponding tetraaminosilanes Si(NHR)4 (2a, R = i-Pr; 2b, R = t-Bu; 2c, R = p-tol) in good yields. When the sterically demanding adamantyl derivative LiHNAd is employed, only disubstitution occurs to form Cl2Si(NHAd)2 (6b). Oxidation of the dimeric imidosilicates {Li3[Si(NR)3(NHR)]·THF}2 (3a, R = i-Pr; 3b, R = t-Bu) with 1 mol of iodine produces the persistent radicals {Li2[Si(NR)3(NHR)]·LiI·3THF}·, which, on the basis of EPR spectra, exist as SiN3Li3I cubes in solution. The spirocyclic tetraimidosilicate monoanion radical {[(THF)2Li(µ-Nnaph)2Si(µ-Nnaph)2Li(THF)2]}–· (10) is formed upon oxidation of the tetralithiated species {Li4[Si(Nnaph)4]·4Et2O} (1) and {[Li(12-crown-4)]2[(Et2O)2Li(µ-Nnaph)2Si(µ-Nnaph)2Li(Et2O)2]} (8) with iodine. The spectroscopic characterization of hexa(amino)disiloxane (t-BuNH)3SiOSi(NH-t-Bu)3 (14) formed from the reaction of Cl3SiOSiCl3 with 6 equiv. of LiNH-t-Bu is discussed. Key words: imido ligands, silicate, radicals, EPR spectra, lithium.

Trioxorhenium(VII) Complexes with Imidazolin-2-iminato Ligands

The Staudinger reaction of the N-heterocyclic carbenes 1,3-di-tert-butylimidazolin-2-ylidene (1a), 1,3-dimesitylimidazolin-2-ylidene (1b) and 1,3-diisopropyl-4,5-dimethylimidazolin-2- ylidene (1c) with trimethylsilyl azide in boiling toluene furnishes the corresponding 2- (trimethylsilylimino)imidazolines 2a - c. Treatment of Re2O7 with a twofold excess of these N-silylated imines results in the formation of the imidazolin-2-iminato trioxorhenium(VII) complexes 3a - c and hexamethyldisiloxane, Me3SiOSiMe3. The molecular structures of 2a, 3a and 3b are reported. In addition, the X-ray crystal structure determination of complex 3c · H2O is presented, which has formed by hydrolysis and cleavage of the metal-nitrogen bond in 3c. 3c · H2O consists of 2-aminoimidazolium cations and tetraoxorhenate(VII) anions, which are linked by N-H-O hydrogen bonds.