Bis niobium

C62H34N18 f 1,2-Di(N-methyl-4-pyridiniurn)ethane tetrakis(7,7,8,8-tetracyanoquinodimethane, 43B, 798 Cs2H65ClsN9Nb3, Tris((di-M chloro)(hexamethylbenzene)niobium) bis(7,7,8,8-tetracyano-p-quinodimethane) acetonitrile solvate, 43B, 799... 

Oxide superconductors have been known since the 1960s. Compounds such as niobium oxide [12034-57-0] NbO, TiO, SrTi02, and AWO, where A is an alkah or alkaline earth cation, were found to be superconducting at 6 K or below. The highest T observed in oxides before 1986 was 13 Kin the perovskite compound BaPb Bi O, x = 0.27. Then in 1986 possible superconductivity at 35 K in the La—Ba—Cu—O compound was discovered (21). The compound composition was later determined to be La 85 A the Y—Ba—Cu—O system was pubUshed in 1987 and reported a transition... 

The radius of the second cation in known MuNbOFs, MU2Nb03F3 and Mul2Nb05F compounds containing bi- and trivalent metals, is usually similar to that of niobium s ionic radius. Such compounds cannot be considered as having an island-type structure and will be discussed later on. Only bismuth-containing compounds (Bi3+) display the presence of different cationic sublattices in their crystal structure. 

Using an electron-gun source, tungsten atoms were reacted with benzene, toluene, or mesitylene at 77 K, to form the expected (arene)2W complex (42) in a yield of 30%, compared with the —2% yield from the previously published, bis(benzene)W synthesis (32). These arene complexes are reversibly protonated, to give the appropriate [(T7-arene)2WH] species. By using the same technique, the analogous, niobium complexes were isolated (43). 

The A-trimethylsilylimines 68 (R = t-Bu, Ph, 2-MeCgH4 or 2-BrC6H4), which are prepared by the reaction of non-enolizable aldehydes with lithium bis(trimethylsilyl)amide, followed by trimethylsilyl chloride, undergo pinacolic coupling induced by NbCLt 2THF to yield the vicinal diamines 69 as mixtures of dl- and meso-isomers, in which the former predominate. Another method for the preparation of 1,2-diamines is by the combined action of the niobium tetrachloride/tetrahydrofuran complex and tributyltin hydride on cyanides RCN (R = /-Hu. Ph, cyclopentyl or pcnt-4-en-l-yl) (equation 32)82. 

Bis(i -benzene)molybdenum(0), 3514 Bis(cyeloetatetraene)uranium(0), 3708 Bis(cyclopentadienyl)bis(pentalluorophenyl)zirconium, 3830 Bis(cyclopentadienyldinitrosylchromium), 3275 Bis(cyclopentadienyl)hexalluoro-2-butynechromium, 3636 Bis(cyclopentadienyl)lead, 3294 Bis(cyclopentadienyl)magnesium, 3277 Bis(cyclopentadienyl)manganese, 3278 Bis(cyclopentadienyl)niobium tetrahydroborate, 3324... 

Nitrile lassen sich mittels Niobium(IV)-chlorid-Bis-tetrahydrofuran/Tributylstannan in Thiolan reduktiv zu vicinalen Diaminen kuppeln1. Die Ausbeuten sind dabei im allge-meinen etwas geringer als bei der vorgenannten, von N-Silyl-iminen ausgehenden Me-thode. 

Bis(arene) [M(jj6-C6H3R3)2] niobium (R = H3, H2Me or 1,3,5-Me3), and less stable tantalum derivatives (R = H3) were prepared in a similar way.714 They are extremely sensitive to oxygen, but relatively stable to water. The photoelectron spectra of the volatile bis(i76-arene) niobium display low values for the first ionization potentials (5.18-5.57 eV), indicating that the compounds are electron rich. The IR spectra of [Nb(C6H3R3)2] (R = H, Me) in an argon matrix at 80 K are in agreement with a symmetrical sandwich structure. 

Bis(cyclopentadienyl)bis(pentafluorophenyl)zirconium, 3824 Bis(cyclopentadienyldinitrosylchromium), 3269 Bis(cyclopentadienyl)hexafluoro-2-butynechromium, 3629 Bis(cyclopentadienyl)lead, 3288 Bis(cyclopentadienyl)magnesium, 3271 Bis(cyclopentadienyl)manganese, 3272 Bis(cyclopentadienyl)niobium tetrahydroborate, 3318 Bis(cyclopentadienyl)pentafluorophenylzirconium hydroxide, 3696 Bis(cyclopentadienyl)phenylvanadium, 3698 Bis(cyclopentadienyl)titanium selenate, 3287 Bis(cyclopentadienyl)tungsten diazide oxide, 3279 Bis(cyclopentadienyl)vanadium diazide, 3280 Bis(cyclopentadienyl)zirconium, 3290 Bis(l,2-diaminoethane)diaquacobalt(III) perchlorate, 1787 Bis(l,2-diaminoethane)dichlorocobalt(III) chlorate, 1780 Bis(l,2-diaminoethane)dichlorocobalt(III) perchlorate, 1781 c/i-Bisf 1,2-diaminoethane)dinitrocobalt(III) iodate, 1782 Bis(l,2-diaminoethane)dinitrocobalt(III) perchlorate, 1778 Bis(l,2-diaminoethane)hydroxooxorhenium(V) perchlorate, 1785 Bis(l, 2-diaminopropane)-ds-dichlorochromium(III) perchlorate, 2609 1,10-Bis(diazonio)decaboran(8)ate, 0197... 

Bis(2,4-pentanedionato)chromium, 3320 Bis(benzene)chromium dichromate, 3845 Bis(benzeneiron)—fulvalenediyl complex, 3828 Bis(cycloctatetraene)uranium(0), 3701 Bis(cyclopentadienyl)bis(pentafluorophenyl)zirconium, 3824 Bis(cyclopentadienyldinitrosylchromium), 3269 Bis(cyclopentadienyl)hexafluoro-2-butynechromium, 3629 Bis(cyclopentadienyl)lead, 3288 Bis(cyclopentadienyl)magnesium, 3271 Bis(cyclopentadienyl)manganese, 3272 Bis(cyclopentadienyl)niobium tetrahydroborate, 3318... 

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