The preparation of new oxoniobium(V) complexes from hydrated Niobium(V) Oxide: the crystal and molecular structure of Oxotris(2-pyridinolato-N-oxide)niobium(V)

Abstract

Three oxoniobium(V) complexes ONbL 3 with HL = tropolone (1), 2-pyridinol-N-oxide (2) or, 3-hydroxy-1,2-dimethyl-4(1H)-pyridone (3) are obtained in good yield by one step reactions from commercially available hydrated niobium(V) oxide in aqueous media. The products are characterized by elemental analysis, FT-IR spectroscopy, NMR spectroscopy ( 1 H-and 13 C-) and thermogravimetry. The crystal structure of oxotris(2-pyridinolato-N-oxide)niobium(V) is determined by single crystal X-ray diffraction, showing discrete molecules with pentagonal bipyramidal coordinated niobium. The 1 H-NMR spectra of CDCl 3 solutions indicate a fluxional behaviour for the three complexes.

Oxido‐ and Sulfidoniobium(V) N,N‐Diethylcarbamates: Synthesis, Characterization and DFT Study

“…Each Nb centre is seven‐coordinate, bonded to seven oxygen atoms that form a distorted pentagonal bipyramid. A similar geometry has been found in the mononuclear complex [NbO( O , O ‐tropolonato) 3 ]6 and in similar complexes 7,8. Thus, each Nb atom is bonded to one oxido, two chelating and two bridging carbamate ligands.…”

“…On the other hand, ME( E , E ) 3 ( E , E = anionic bidentate ligand) compounds have been reported for all the possible combinations of hard/soft metal‐ligated atoms. Examples are [NbO( O , O ‐tropolonato) 3 ],6 [NbO( O , O ‐2‐pyridinolato N ‐oxide) 3 ],7 [NbO( O , O ‐8‐hydroxyquinolinato) 3 ],8 [NbO(S 2 CNEt 2 ) 3 ]9 and [MS(S 2 CNEt 2 ) 3 ]10 (M = Nb, Ta). This series does not include N , N ‐dialkylcarbamato species.…”

A series of compounds containing various (oxalato)tantalate(v) complex anions – synthesis, properties and the mixed-metal oxide formation via thermal decomposition

“…The arrangement of the axial and equatorial atoms found in compounds 2-4 is very common also in other sevencoordinate molecules with three bidentate and one monodentate ligands. 37 The bond distances and angles of the [Ta(L)(C 2 O 4 ) 3 ] 22 anions in 2-4 are given in Table 5.…”

Influência da substituição de cimento por pentóxido de nióbio na resistência à compressão de argamassas

“…1.3 Óxido de Nióbio(V) Hidratado e Anidro O óxido de nióbio(V) (Nb 2 O 5 ) é o produto intermediário dos processos industriais de produção de nióbio, tendo cor branca e tornando-se amarela com aquecimento, mas que desaparece com o resfriamento (SERAFIM, 2007). O óxido de nióbio(V) hidratado ou "ácido nióbico" (Nb 2 O 5 nH 2 O), apresenta grande estabilidade com relação à maior parte dos reagentes ácidos, exceto aos ácidos fluorídrico, sulfúrico concentrado e clorídrico.…”