460. Normal alkoxides of quinquevalent niobium

Abstract

The new alkoxides Nb(OR),, where R = Me, Et, Prn, Bun, or n-pentyl, have been prepared by reactions involving niobium pentachloride, the alcohol, and ammonia, or by alcohol-interchange involving niobium pentaethoxide. Boiling points under reduced pressure and ebullioscopic molecular weights in benzene, in toluene, and in the parent alcohols were determined. The niobium n-alkoxides are less stable than the corresponding tantalum compounds. The volatilities and molecular complexities of the niobium and tantalum n-alkoxides are discussed from the theoretical viewpoint.THE preparation and properties of some tantalum penta-n-alkoxides have recently been described.l In view of the chemical similarity between niobium and tantalum it seemed worthwhile to investigate the alkoxides of niobium. Additional interest was centred on the relative volatilities of corresponding niobium and tantalum alkoxides because of the possibility that the effect of molecular weight on volatility might be apparent. This communication deals with the rt-alkoxides Nb(OR),, where R = Me, Et, Prn, Bun, and ut-pentyl.These compounds may be prepared by either of the methods :Niobium pentamethoxide is a white crystalline solid, m. p. 60" [cf. Ta(OMe),, m. p. 50"], but the other rt-alkoxides are pale yellow liquids. The ease of hydrolysis in water appears to parallel the water-miscibility of the parent alcohols. A notable feature of the niobium rt-alkoxides is the decrease in thermal stability with increase in length of the alkyl chain in contrast to the behaviour of the corresponding n-alkoxides of tantalum. Thus distillation of niobium ut-pentyloxide causes decomposition even at 0.1 mm. whereas tantalum rt-pentyloxide boils unchanged at a higher temperature. The boiling points of niobium and tantalum rt-alkoxides under reduced pressure are presented in the Table : their main

Microemulsion mediated synthesis of nanocrystalline (Kx,Na1−x)NbO3 powders

“…Precipitated ammonium chloride was filtered off under argon and toluene in the filtrate was removed by distillation at 110 1C. Pure niobium ethoxide was isolated by vacuum distillation at 168 1C and 0.1 mbar [22] and mixed with a stoichiometric amount of pure sodium ethoxide and potassium ethoxide (both ABCR) corresponding to the desired K/Na-ratio respectively. After the preparation of the precursor solutions a microemulsion, consisting of 10.06 wt% Lutensol s ON 110 (BASF), a commercial C 10 oxoalcohol ethoxylate with an average degree of ethoxylation of 11, 81.36 wt% cyclohexane (Riedel de Hae¨n, analytical grade), 5.94 wt% 1-octanol (Merck, analytical grade) and 2.64 wt% of ultrapure degassed water, was added.…”

Organic Reaction Pathways in the Nonaqueous Synthesis of Metal Oxide Nanoparticles

“…[193,194] Ether elimination reactions are characteristic of the derivatives of multivalent early transition elements such as Mo [195,196] …”

Synthesis of the first examples of stable heterometallic isopropoxides of an organometallic RSn(IV) moiety

“…93°/10 mm) before use. Isopropoxides of aluminium [32], gallium [33], and niobium [34] were prepared by the literature procedures. Aluminium and gallium were estimated as their oxinates [35], while niobium and tin were estimated as their oxides [35].…”