Niobium complexes organometallic

Acetyl ligands, in niobium complexes, C-H BDEs, 1, 298 Achiral phosphines, on polymer-supported peptides, 12, 698 Acid halides, indium compound reactions, 9, 683 Acidity, one-electron oxidized metal hydrides, 1, 294 Acid leaching, in organometallic stability studies, 12, 612 Acid-platinum rf-monoalkynes, interactions, 8, 641 Acrylate, polymerization with aluminum catalysts, 3, 280 Acrylic monomers, lanthanide-catalyzed polymerization,... 

Bemo, P. and Gambarotta, S., Formation of a metalaaziridine ring and dinitrogen fixation promoted by a niobium amide complex. Organometallics, 14 (1995) 2159-2161. 

Monomeric, paramagnetic chlorohydrides snch as MH2CI2 (PR3)4 derive from facile oxidative addition of H2 to MCl2(PR3)4 complexes. Of these 17e dodecahedral complexes, (32) is the most interesting (eqnation 17). Its thermolysis in solution offers a qnadruply bridged hydride (33) and it can also be rednced to a monomeric Ta 16e species (34). Ta hydrides display a hydridic character (see Hydride Complexes of the Transition Metals), as shown by the reduction of CO by cyclopentadienyl derivatives. (see Niobium Tantalum Organometallic Chemistry)... 

Metal-mediated Protein Modification Niobium Tantalum Organometallic Chemistry Polynuclear OrganometaUic Cluster Complexes. 

Carbonyl Complexes of the Transition Metals Mechanisms of Reaction of Organometallic Complexes Niobium Tantalum Organometallic Chemistry. 

Galajov M, Garcia C, Gomez M, Gomez-Sal P, Temprado M. Synthesis and DFT, multinuclear magnetic resonance, and X-ray stmctural studies of iminoacyl imido hydridotris(3,5-dimethylpyrazolyl)borate niobium and tantalum(V) complexes. Organometallics. 2014 33 2277-2286. 

Fryzuk MD, Kozak CM, Bowdridge MR et al (2002) Cyclohexadienyl niobium complexes and arene hydrogenation catalysis. Organometallics 21 5047-5054... 

Kopf-Maier P, Kopf H (1994) Organometallic titanium, vanadium, niobium, molybdenum and rhenium complexes - early transition metal antitumor drugs. In Fricker SP (ed) Metal Compounds in Cancer Therapy. Chapman Hall, London, pp 109-146... 

Last but not least, mention should be made of the use of redox active organometallic clusters for the formation of CT complex. An early example was reported by Eisenberg, Miller and co-workers who exploited the trinuclear niobium cluster [Nb3(/i-Cl)6(>7 -C6Me6)3] and prepared the [TCNQ] salt, upon oxidation to the dicationic form. This material was found to be paramagnetic and to display a relatively modest conductivity (urt = 0.001 Scm , semiconductor) [75]. Finally, the pentanuclear trigonal bipyramidal vanadium cluster [(MeCp)5V5(/r -S)6] was shown to undergo CT complex formation with TCNQ affording [(MeCp)5V5(/i -S)6] [(TCNQ)2] [76]. This material, which was structurally characterized, is an n-type semiconductor with a band gap of 0.25 eV. 

The most important starting materials for organometallic complexes of niobium and tantalum are their pentachlorides, NbCls and TaCls. The commercially available pentachlorides can be sublimed if further purification is necessary. They are commonly used for access to both high-valency and low-valency compounds. The crystal structure of NbCl5 consists of dimeric Nb2Cl owith two chlorides bridging as shown in Scheme 7.8, and the Ta analogue is presumed to have a similar structure. In non-... 

Although group 5 organometallic systems have been found to be of relevance in transition-metal catalyzed hydroboration reactions, structurally authenticated group 5 boryl complexes remain relatively few in number. Smith and co-workers, for example, have probed the mechanisms for the formation of niobium and tantalum mono- and bis(boryls) from propylene complex precursors, with concomitant formation of propyl boronate esters [31,32]. Of particular interest from a structural viewpoint are the relative merits of alternative bonding descriptions for metal(V) boryl bis(hydrides) as borohydride complexes or as mono(hydride) a-borane systems [31-34]. 

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