Applications of Vanadium, Niobium, and Tantalum Complexes in Organic and Inorganic Synthesis

Abstract

Organometallic catalysis is a powerful strategy in chemical synthesis, especially with the cheap and low toxic metals based on green chemistry principle. Thus, the selection of the metal is particularly important to plan relevant and applicable processes. The group VB metals have been the subject of exciting and significant advances in both organic and inorganic synthesis. In this Review, we have summarized some reports from recent decades, which are about the development of group VB metals utilized in various types of reactions, such as oxidation, reduction, alkylation, dealkylation, polymerization, aromatization, protein synthesis, and practical water splitting.

Low-Valent Niobium Catalysis for the Polymerization of Electron-Rich Diphenylacetylenes

“…Nb­(III) species have often been proposed as key intermediates in low-valent Nb catalysis. − Therefore, we thought that Nb­(III) species might participate in the polymerization of diphenylacetylenes with the NbCl 5 -PhSiH 3 system. To obtain information about an intermediate in the polymerization, we prepared an Nb­(III) species by treatment of NbCl 5 with 3,6-bis­(trimethylsilyl)-1,4-cyclohexadiene ( 2 ), which is an electron-donating reagent, in toluene at 80 °C according to the method reported by Mashima and co-workers (Scheme ).…”

“…Niobium (Nb), which is one of the group 5 metals, has attracted attention in the field of catalysis because various useful chemical transformations have been realized by Nb catalysis. − High-valent Nb­(V) complexes ( d 0 complexes), such as niobium­(V) chloride (NbCl 5 ), are the most stable forms of Nb like other early transition metals such as vanadium, tantalum, tungsten, and molybdenum, which are often used as catalysts in organic synthesis. − On the other hand, low-valent Nb complexes can be formed as thermally stable species from Nb­(V) compounds and reducing reagents, and such species often catalyze unique reactions in organic synthesis. ,,− Two representative examples of such catalytic reactions are shown in Figure a. In 2006, Fuchibe and Akiyama reported transformation of o -trifluoromethylbiphenyl derivatives into fluorene derivatives via activation of strong C–F bonds catalyzed by the low-valent Nb species formed from NbCl 5 and lithium aluminum hydride (LiAlH 4 ) in situ (Figure a, eq 1) .…”

Not So Similar: Different Ways of Nb(V) and Ta(V) Catecholate Complexation

“…The redox behavior of Nb(V) and Ta(V) complexes with catecholate derivatives under air-free conditions is quite interesting but rare [38,39]. The most straightforward results in the field belong to Ta(V) complexes with N,N-bis(3,5-di-tert-butyl-2-phenoxide)amide, which is active in the four-electron oxidative formation of aryl diazenes [40].…”

Hierarchical Zeolites Containing Vanadium or Tantalum and Their Application in Cyclohexene Epoxidation Reaction

“…Vanadium and tantalum are attracting increasing attention from scientists, including ours. Vanadium is a relatively non-toxic and inexpensive element thanks to which it plays an important role in biochemistry and medicinal chemistry and its diversity in coordination chemistry has also led to applications in synthesis and catalysis [17]. Tantalum, on the other hand, is an element very similar to niobium in terms of its physicochemical propertiesthese elements were thought to be one element when they were discovered in the early 19th century.…”

“…Tantalum, on the other hand, is an element very similar to niobium in terms of its physicochemical propertiesthese elements were thought to be one element when they were discovered in the early 19th century. According to the literature data, niobium is a widely used metal in catalytic reactions, so high hopes are placed in tantalum and the recent literature reviews clearly illustrate the progress of this element in catalysis [17]. Given the above information, we decided to investigate the catalytic activity of tantalum and vanadium in the epoxidation reaction of cyclohexene.…”