Niobium alkyl

Scheme 5.10 describes the synthesis of niobium alkyl complex [Nb(R-L)Me2l2, 38, obtained from the reaction of niobium chloride complex [Nb(Me-L)Cl2]2, 37, and borate reagent [199]. Compound 37 can be prepared from the reaction of [NbClj] and 2,6-bis(4,6 dimethylsalicyl)-4-ferf-butylphenol [H3(Me-L)] or 2,6-bis(4-methyl-6-tert-butylsalicyl)-4-ferfbutylphenol [HjlBu -L)] in toluene. The Nb-Nb bond distances in these two chloro complexes are 3.554(1) and 3.649(1) A, respectively. 

Niobium, tris(diethyldilhiocarbamato)oxy-stereochemistry, 1,82 structure, 1, 83 Niobium, tris(oxa ato)oxy-stereochcmistry, 1, 82 Niobium, tris(phcnylcncdirhio)-structure, 1, 63 Niobium alanate, 3, 685 Niobium complexes alkyl alkoxy reactions, 2, 358 amides, 2,164 properties, 2, 168 synthesis, 2, 165 applications, 6,1014 carbamicacid, 2, 450 clusters, 3, 672,673,675 hexamethylbenzene ligands, 3, 669 cyanides synthesis, 2, 9 p-dinitrogen, 3, 418 fluoro... 

Homoleptic Nbv and Tav dialkylamides have been obtained (equation S).263,264 Extensive reduction, increasing with the length of the alkyl chain, was observed with niobium, the predominant products then being [Nb(NR2)4] (R = Et, Pr , Bun Section 34.3.5.4). Oxidation... 

The strong Lewis acid niobium(V) pentachloride has been found to be an effective reagent for the monodealkylation of diethers with two alkyl-aryl linkages.128... 

C-M bond addition, for C-C bond formation, 10, 403-491 iridium additions, 10, 456 nickel additions, 10, 463 niobium additions, 10, 427 osmium additions, 10, 445 palladium additions, 10, 468 rhodium additions, 10, 455 ruthenium additions, 10, 444 Sc and Y additions, 10, 405 tantalum additions, 10, 429 titanium additions, 10, 421 vanadium additions, 10, 426 zirconium additions, 10, 424 Carbon-oxygen bond formation via alkyne hydration, 10, 678 for aryl and alkenyl ethers, 10, 650 via cobalt-mediated propargylic etherification, 10, 665 Cu-mediated, with borons, 9, 219 cycloetherification, 10, 673 etherification, 10, 669, 10, 685 via hydro- and alkylative alkoxylation, 10, 683 via inter- andd intramolecular hydroalkoxylation, 10, 672 via metal vinylidenes, 10, 676 via SnI and S Z processes, 10, 684 via transition metal rc-arene complexes, 10, 685 via transition metal-mediated etherification, overview,... 

Cyclopentadienones, in molybdenum carbonyls, 5, 451 Cyclopentadienyl alkenes, with niobium, 5, 76 Cyclopentadienyl-alkoxo complexes, with Ti(IV), 4, 495 Cyclopentadienyl alkyl complexes, with niobium, 5, 66 Cyclopentadienyl-amido complexes, with Ti(IV), via dehalosilylation, 4, 448... 

Considering the presently available knowledge on vanadium(V) compounds, reaction (58b) seems to be more attractive, as compounds of types (RO)3VO, (RO)3V=NR, etc., are well documented for both R = alkyl and R = silyl (4, 81), whereas only very few VX6 species are known. The pertinent chemistry of the congeners niobium and tantalum offers examples for pentacoordination as well as for ylide formation. 

Organometallic Niobium ) and Tantalum ) Compounds. Reports this year have concerned two main areas of interest the preparation of alkyl-niobium and tantalum halides and their reactions with donor ligands, and insertion reactions into methyl-metal bonds. The first examples of monomethyl niobium and tantalum compounds have been prepared by the low-temperature methylation of the appropriate halides... 

HEXAHALOGENO SALTS AND ALKYL NITRILE COMPLEXES OF TITANIUM(IV), ZIRCONIUM(IV), NIOBIUM(V), TANTALUM(V), PROTACTINIUM (IV) AND -(V), THORIUM(IV), AND URANIUM(IV)... 

G. L. Juvinall, cr-Bonded Alkyl Compounds of Niobium and Tantalum. Trimethyldi-chloroniobium and Trimethyldichlorotantalum, J. Am. Chem. Soc. 86,4202 4203 (1964). 

Niobium and tantalum methyls, Me3MCl2, were among the first known stable transition metal methyls. Other partially substituted alkyls, as well as the penta-methyl, are also known. The structure of TaMe5 is square-pyramidal73 but Me3TaF2 is trigonal-bipyramidal.74 These compounds are made by the reactions ... 

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