Search

1-Arylthio-2-naphthols are obtained as an unexpected result of the nucleophilic aromatic substitution reaction of β-naphthyl triflates with thiophenols.

The new iridium complex is found to be an efficient catalyst to produce various α-substituted ketones with high enantioselectivity.

The structures of group 14 C-metalated 6-amino-1-azafulvene dimers have been investigated in solution and in the solid state by NMR spectroscopy. For one of these compounds, 5,10-bis(dimethylamino)-3,8-bis(trimethylstannyl)-5H,10H-dipyrrolo[1,2-a: 1',2'-d]-pyrazine (2c), the molecular structure in the solid state has been determined by X-ray diffractometry. The two tin centers have a distorted-trigonal-bipyramidal co-ordination geometry with the more electronegative N ligand at a pseudoaxial position, resulting in one of the longest known Sn - N interactions: 3.101 (5) A°. Moreover, the temperature-dependent 13C CP-MAS NMR spectrum of this compound shows an appreciable narrowing of the Me3Sn signal between 296 and 333 K. By comparison with nonmetalated analogs or with isomer 5c, the nonreactivity of compound 2c toward hydrolytic decomposition into corresponding 5-(trimethylstannyl)-pyrrole-2-carbaldehyde (3c) may be the result of stabilization of the dimeric form 2c by a double Sn - N interaction. In silicon and germanium analogs (2a, 2b) the Si(Ge) - N interaction is weaker.

Reaction of the chlorophosphite Cl[graphic omitted] 1 with cyclohexylamine gave the expected product (C6H11NH)[graphic omitted] 3 whereas the corresponding chloroarsenite 2 led to the bridged compound 12. When the reaction was performed in the presence of water, 1 gave the expected product H(O)[graphic omitted] 11 whereas 2 gave the oxo-bridged compound ([graphic omitted])2O 13. The amino phosphite 3 underwent hydrolysis to afford the ring cleaved product 18 whereas the phenoxy phosphite 21 led to the ring preserved compound 11. In contrast, the corresponding phenoxy arsenite (PhO)[graphic omitted] 25 gave the oxo-bridged compound 13. Addition of perchloro-o-benzoquinone to the phosphite 23 was highly exothermic and afforded the phosphorane 29; however the corresponding arsenonate 27 reacted very sluggishly at room temperature and when heated gave an uncharacterizable mixture of products.The identity of the title oxy-bridged compounds 13 and 15 obtained here has been confirmed by X-ray structure determination; the six-membered rings in 13 have a ‘chair’ conformation and the eight-membered rings in 15 have a ‘symmetrical anti’ conformation.

Nanocomposite containing a homogeneous dispersion of NdAlO3 crystallites in an Al2O3 matrix has been obtained from the chemical vapour deposition of the mixed-metal precursor [Nd{Al(OPri)4}3(PriOH)].

Nanostructured ZnFe2O4 and zinc oxide−iron oxide composites were obtained by sol−gel processing of a hetero-bimetallic alkoxide. For this purpose the novel molecular precursors Fe2Zn(OR)8 (R = tBu, iPr), fully characterized by spectroscopic and single-crystal diffraction techniques, have been synthesized and their applications in the sol−gel procedure were investigated. The obtained xerogels were annealed at very low temperatures (down to 200 °C) yielding crystalline phases with very small crystallite grain sizes. The phase compositions of the material strongly depend on the polarity of the solvents used in the hydrolysis reaction. When the hydrolysis was performed in the polar propan-2-ol, the spinel ZnFe2O4 (franklinite) formed at annealing temperature of 200 °C with a mean crystallite grain size Dvol of 2.24 nm. However, when using the less polar toluene as solvent in the sol−gel process, iron oxide and zinc oxide are formed together with the franklinite phase. This mixture of phases transforms to the ...

Iron(III) tert-butoxide, [Fe(O t Bu) 3 ] 2 , was used as a single source for iron and oxygen to obtain nanocrystalline hematite (Fe 2 O 3 ) or magnetite (Fe 3 O 4 ) films by low-pressure (LP) CVD. The decomposition profile of the molecular precursor and the crystallization temperature of iron oxide were derived from thermogravimetry/differential thermal analysis (TG/DTA). The substrate temperature was found to markedly influence the morphology and Fe/O stoichiometry in the deposited films. The morphological features and phase identification of the grown films were obtained by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The compositional identity of the phases was determined by the X-ray photoelectron spectroscopy (XPS) of the CVD deposits. Annealing the films ex-situ under reducing or oxidizing conditions allows selective interconversion (Fe 2 O 3 ↔ Fe 3 O 4 ) among the deposited phases with no particle size variation. The interplay between the rate of precursor delivery and substrate temperature controlled the mean particle size in the films. Magnetite film with a mean particle size of 10 nm was obtained on silicon at 450 °C. Formation of larger grains and grain clusters was observed at higher temperatures. High coercivity (4000 Oe) and small saturation magnetization (0.3 emu g -1 ) of the Fe 3 O 4 film confirmed superparamagnetic behavior due to small particle size. Absorption spectra of magnetite and hematite films deposited on glass show them to be transparent to the visible light. The sheet resistance of nanocrystalline Fe 3 O 4 and Fe 2 O 3 films was found to be 2.4 kΩ and 2 MΩ, respectively.

The reaction of Me2Si(N-t-Bu)2ECl (E = Sb, Bi) with NaM(CO)nCp (M = Fe, Mo, W; Cp = ?5-C5H5) affords metallastibanes and bismuthanes, Cp(CO)nME(N-t-Bu)2SiMe2 (4a-c, 5a-c). The structures of 4c (E = Sb, M = W) and 5c (E = Bi, M = W) have been determined by X-ray crystallography. Both compounds are isotypic and isostructural and crystallize in the triclinic space group with a = 7.030 (9) A°, b = 10.51 (1) A°, c = 16.22 (2) A°, a = 94.1 (1)°, s = 90.4 (1)°, ? = 104.9 (1)°, Z = 2 for 4c and a = 7.014 (9) A°, b = 10.57 (1) A°, c = 16.25 (2) A°, a = 94.1 (1)°, s= 90.1 (1)°, ? = 104.6 (1)°, Z = 2 for 5c. The E-W s-bond lengths are 3.010 (1) A° for E = Sb and 3.082 (1) A° for E = Bi. The reaction of the antimony derivatives with Fe2(CO)9 yields [Fe(CO)4]Cp(CO)nMSb(N-t-Bu)2SiMe2 (6a-c) as a result of the complexation of the antimony lone pair. The crystal structures of 6a (M = Fe) and 6b (M = Mo) have been determined. 6a crystallizes in the monoclinic space group with a = 10.399 (9) A°, b = 16.76 (2) A°, c = 15.74 (1) A°, s = 94.16 (6)°, and Z = 4. Both Sb-Fe bond lengths are almost similar: 2.547 (1) A° for the covalent bond and 2.530 (1) A° for the dative bond. 6b crystallizes in the monoclinic space group with a = 12.305 (7) A°, b = 13.812 (7) A°, c = 16.75 (1) A°, s = 99.03 (5)°, and Z = 4. The Sb-Mo covalent bond length is 2.871 (1) A° and the Sb-Fe dative bond 2.539 (1) A°.