13597-20-1Relevant articles and documents
Polar [NbOCl3]2n and [NbOX4 -]n (X = Cl, Br) chains in the structures of NbOCl 3 and the thallium-halogenooxoniobates Tl[NbOCl4] and Tl[NbOBr4] - Synthesis, crystal structures and optical second harmonic generation
Beck, Johannes,Bordinhao, Jairo
, p. 1261 - 1266 (2005)
The reactions of thallium(I)halides TlCl and TlBr with Nb2O 5 and NbCl5, and NbBr5, respectively, under the conditions for chemical vapour transport in closed evacuated ampoules in a temperature gradient from 350°C to 300°C give yellow Tl[NbOCl 4] and red Tl[NbOBr4] in 50 % yield. The crystal structures (Tl[NbOCl4]: orthorhombic. Pbca, a = 1259.9(1), b = 791.9(1), c = 1506.9(1) pm; Tl[NbOBr4]: monoclinic, C2, a = 1304.9(3), b = 402.7(3), c = 770.6(3) pm, β = 108.150(3)) are built of linear chains of associated [NbOX4-]n (X = Cl, Br) ions and of Tl+ ions located between the chains. The individual square-pyramidal [NbOX4-] ions are linked by asymmetric O...Nb-O bridges. The Tl+ ions are coordinated by halogen atoms in form of strongly distorted square antiprisms for X = Cl, and in form of cubes for X = Br. The two structures are not isotypic even though they are made up of analogous building units. The centrosymmetry of the Tl[NbOCl4] structure causes the polar chains to run in opposite directions. The structure of Tl[NbOBr4] is acentric and the polar [NbOBr4 -]n chains all point into the same direction. An optical second harmonic generation experiment confirmed the recently performed redetermination of the structure of NbOCl3 (Stroebele, Meyer 2002). NbOCl3 crystallizes acentric with analogously polar [Nb 2O2Cl6]n chains.
SOME PHOSPHINE OXIDE AND SULPHOXIDE COMPLEXES OF Nb(V), Mo(V) AND W(VI) OXOCHLORIDES.
Behzadi,Baghlaf,Thompson
, p. 103 - 110 (1978)
The new complexes MoOCl//3 multiplied by (times) 2Ph//2SO and WOCl//4 multiplied by (times) Ph//3PO have been prepared by the reaction of MoCl//5 and WOCl//4 with the appropriate ligand. These complexes have been characterized by analysis, infrared and Ra
Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes
Bortoluzzi, Marco,Ferretti, Eleonora,Marchetti, Fabio,Pampaloni, Guido,Pinzino, Calogero,Zacchini, Stefano
, p. 4173 - 4182 (2016)
The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems.
Oxido- and sulfidoniobium(V) N,N-diethylcarbamates: Synthesis, characterization and DFT study
Bortoluzzi, Marco,Ghini, Franco,Hayatifar, Mohammad,Marchetti, Fabio,Pampaloni, Guido,Zacchini, Stefano
, p. 3112 - 3118 (2013)
N,N-Diethylcarbamates [NbE(O2CNEt2)3] (E = O, S) have been prepared in high yields by treating NbOCl3 or [NbSCl3(CH3CN)2] with CO2/NHEt 2 in toluene at approximately -10 °C. The products were characterized by spectroscopic techniques, elemental analysis and X-ray diffractometry in the case of [NbO(O2CNEt2)3]. The molecular structure of the latter consists of a niobium centre coordinated to the oxido moiety and six O atoms belonging to bridging and bidentate carbamates, in a slightly distorted pentagonal-bipyramidal arrangement. The structures of both [NbE(O2CNEt2)3] compounds were reproduced by DFT calculations, which show substantial similarity despite the different nature of the chalcogen atoms. N,N-Diethylcarbamates [NbE(O 2CNEt2)3] (E = O, S) have been prepared from NbECl3 and fully characterized. The structures of both products have been optimized by DFT calculations.
Electronic Absorption Spectra of Reduction Products of Pentavelent Niobium and Tantalum in Different Alkali Chloride and Oxychloride Melts
Bachtler, M.,Rockenberger, J.,Freyland, W.,Rosenkilde, Chr.,Ostvold, T.
, p. 742 - 747 (1994)
We have studied the elctronic absorption spectra of niobium chloride and oxychloride compounds in different oxidation states and of the reduction products of pentavalent niobium and tantalum in various alkali chloride melts at different temperatures up to
Fragmentation of oxygen-containing molecules via C-O bond cleavage promoted by coordination to niobium and tantalum pentahalides
Marchetti, Fabio,Pampaloni, Guido,Zacchini, Stefano
, p. 6759 - 6772 (2009)
The novel μ-oxo complexes NbOX3[κ2-O(Me) CH2CO2Me]NbX5 (X = Cl, 3a; X = Br, 3b), NbOCl3[κ2-(MeO2C)CHCH(CO 2Me)]NbCl5 (7) and NbOCl3[κ
Revised crystal structure of NbOCl3
Stroebele, Markus,Meyer, Hans-Juergen
, p. 488 - 491 (2002)
NbOCl3 was obtained from a reaction of NbCl5 and Nb2O5 at 260°C. Contrary to the literature data, NbOCl3 crystallizes in the non-centrosymmetric space group P421m as determined by single-crystal and powder X-ray diffraction data (crystal: a = b = 1089.59(6) pm, c = 394.79(2) pm, Z = 4, R1 = 0.0229, wR2 = 0.0459, powder: a = b = 1086.36(6) pm, c = 393.65(2) pm). The niobium atoms are surrounded by distorted octahedra built of four chlorine atoms and two oxygen atoms in trans positions. Two such octahedra are edge-bridged through shared chlorine atoms, forming dimers. These units are linked to each other by apical oxygen atoms forming one-dimensional Nb2Cl6O2 chains parallel [001]. Contrary to the literature data two different Nb-O distances are obtained.
Niobium-93 Nuclear Magnetic Resonance Studies of the Solvolysis of NbCl5 by Alcohols
Lee, G. Robert,Crayston, Joe A.
, p. 3073 - 3076 (1991)
Niobium-93 and 1H-NMR spectroscopy have been used to identify the substitution products NbCl5-x(OMe)x formed by the stepwise substitution of NbCl5 by MeOH in non-co-ordinating solvents.This reveals evidence for all of the possible su
Formation and thermochemical properties of oxychlorides of niobium (Nb) and tantalum (Ta): Towards the gas-phase investigation of dubnium (Db) oxychloride
Chiera, Nadine M.,Sato, Tetsuya K.,Tomitsuka, Tomohiro,Asai, Masato,Suzuki, Hayato,Tokoi, Katsuyuki,Toyoshima, Atsushi,Tsukada, Kazuaki,Nagame, Yuichiro
, p. 361 - 366 (2019)
The formation of NbOCl3 and TaOCl3 and their adsorption behavior on quartz surfaces was explored by applying an isothermal gas-chromatographic method. Trace amounts of short-lived Nb and Ta isotopes were used. Adsorption enthalpy values (ΔHads) at zero surface coverage of –ΔHads(NbOCl3) = 102 ± 4 kJ/mol and –ΔHads(TaOCl3) = 128 ± 5 kJ/mol were determined by analyzing the chromatographic behavior of the Nb and Ta complexes with a Monte-Carlo simulation method based on an adsorption–desorption kinetic model. By applying an empirical correlation, the experimental ΔHads values were successively related to the macroscopic standard sublimation enthalpy, ΔH°subl, as a measure of the volatility of each substance. The inferred sublimation enthalpies are in agreement with tabulated thermochemical values. Thus, the linear empirical correlation between ΔHads and ΔH°subl for metal-oxychlorides was updated with the inclusion of the present data. According to the predicted ΔH°subl(DbOCl3), a ΔHads(DbOCl3) value of 135 ± 2 kJ/mol was extrapolated. The future accomplishment of comparative studies with DbOCl3 under the same experimental conditions will provide valuable information on the volatility trend in Group-5 elements, together with an indication on the magnitude of relativistic effects on the electronic structure of dubnium.
Decarbonylation of phenylacetic acids by high valent transition metal halides
Bartalucci, Niccolò,Marchetti, Fabio,Zacchini, Stefano,Pampaloni, Guido
, p. 5725 - 5734 (2019/05/10)
Triphenylacetic acid underwent unusual decarbonylation when allowed to react with a series of halides of group 4-6 metals in their highest oxidation state, in dichloromethane at ambient temperature. Thus, the reaction of CPh3COOH with MoCl5, in 1:1 molar ratio, afforded the trityl salt [CPh3][MoOCl4], 1, in 79% yield, while the 1:2 reaction of CPh3COOH with NbF5 afforded [CPh3][NbF6], 2, in 70% yield, NbOF3 being the metal co-product. CPh3COOH reacted with NbCl5, TiF4 and WOCl4 to give mixtures of compounds, however the cation [CPh3]+ was NMR identified in each case. [CPh3][NbCl6], 3, was isolated from NbCl5 and CPh3COCl, prior to being generated from CPh3COOH and PCl5. The reaction of CPh3COOH with TiCl4 was non-selective, and the salt [CPh3][Ti2Cl8(μ-κ2-O2CCPh3)], 4, was obtained in 18% yield. The decarbonylation reactions of CMePh2COCl and CMe2PhCOCl by means of NbCl5 led to the indanes 5a-b, which were isolated in 79-97% yields after hydrolysis of the mixtures and subsequent alumina filtration of the organic phases. The reactions of CH(Ph)2COOH with NbCl5 and WCl6 afforded NbCl4(OOCCHPh2), 6, and CHPh2COCl, respectively, as the prevalent species. CPh2(CH2CH2Br)COOH did not undergo CO release when allowed to interact with WCl6, instead selective intramolecular condensation to C(Ph)2C(O)OCH2CH2, 7, occurred. MeCCCOOH underwent hydrochlorination by WCl6 to give MeC(Cl)CHCOOH, 8, in 72% yield. All the products were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy. In addition, the solid state structures of 1, 2, 4, 7, and 8 were elucidated by X-ray diffraction.
