Vanadium, niobium and tantalum

Fulton, J. Robin

doi:10.1039/c3ic90021e

Cited by 4 publications

(2 citation statements)

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“…The application of tantalum compounds in catalytic reactions has also attracted significant attention. Several recent reviews clearly illustrate advances and achievements of group VB element chemistry in different fields. − …”

Section: Introductionmentioning

confidence: 99%

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

Wang

Tan

et al. 2022

ACS Org. Inorg. Au

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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.

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Section: Introductionmentioning

confidence: 99%

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

Wang

Tan

et al. 2022

ACS Org. Inorg. Au

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“…There have been reports of different reactivities of Nb(V) and Ta(V) compounds. − Our search of the literature, including the 1904–2013 annual reviews on niobium and tantalum chemistry by the Royal Society of Chemistry, shows that the reduction of Nb(V) complexes to Nb(IV) species is more likely than their Ta(V) analogues, − which is a major difference between the Nb(V) and Ta(V) chemistries. Bradley and Thomas have reported several reactions between MCl 5 [M = Nb(V); Ta(V)] and LiNR 2 (R = Me, Et, n Pr, n Bu). , As the alkyl chains increase, the extent of Nb(V) to Nb(IV) reduction increases in the products, while tantalum complexes remains at Ta(V).…”

Section: Introductionmentioning

confidence: 99%

Syntheses of Group 5 Amide Amidinates and Their Reactions with Water: Different Reactivities of Nb(V) and Ta(V) Complexes

et al. 2022

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Chemistries of Nb(V) and Ta(V) compounds are essentially identical as a result of lanthanide contraction. Hydrolysis of M(NMe 2 ) 5 (M = Nb, Ta), for example, yields [M(μ 3 -O)(NMe 2 ) 3 ] 4 (M = Nb, 1; Ta, 2) reported earlier. The similar reactivities of Nb(V) and Ta(V) compounds make it challenging, for example, to separate the two metals from their minerals. We have found that the reactions of H 2 O with amide amidinates M(NMe 2 ) 4 [MeC(N i Pr) 2 ] (M = Nb, 3; Ta, 4) show that the niobium and tantalum analogues take different principal paths. For the Nb(V) complex 3, the amidinate and one amide ligand are liberated upon treatment with water, yielding [Nb(μ 3 -O)(NMe 2 ) 3 ] 4 (1). For the Ta(V) complex 4, the amide ligands are released in the reaction with H 2 O, leaving the amidinate ligand intact. [Ta(μ 3 -O)(NMe 2 ) 3 ] 4 (2), the analogue of 1, was not observed as a product in the reaction of 4 with H 2 O. To our knowledge, this is the first example of the formation of two different complexes that maintain the (V) oxidation state in both metals. The new complexes M(NMe 2 ) 4 [MeC(N i Pr) 2 ] (M = Nb, 3; Ta, 4) have been prepared by the aminolysis of M(NMe 2 ) 5 (M = Nb, Ta) with i PrN(H)C(Me)=N i Pr (5). The hydrolysis of 3 and 4 has been investigated by DFT electronic structure calculations. The first step in each hydrolysis reaction involves the formation of a hydrogen-bonded complex that facilitates a proton transfer to the amidinate ligand in 3 and protonation of an axial dimethylamide ligand in 4. Both proton transfers furnish an intermediate metal-hydroxide species. The atomic charges in 3 and 4 have been computed by Natural Population Analysis (NPA), and these data are discussed relative to which of the ancillary ligands is protonated initially in the hydrolysis sequence. Ligand exchanges in 3 and 4 as well as the exchange in i PrN(H)C(Me)=N i Pr (5) were probed by EXSY NMR spectroscopy, giving rate constants of the exchanges: 0.430(13) s −1 (3), 0.033(6) s −1 (4), and 2.23(7) s −1 (5), showing that the rate of the Nb complex Nb(NMe 2 ) 4 [MeC(N i Pr) 2 ] (3) is 13 times faster than that of its Ta analogue 4.

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Nb Complexes

Kurogi

Mindiola

2021

Comprehensive Coordination Chemistry III

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Vanadium, niobium and tantalum

Cited by 4 publications

References 96 publications

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

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

Syntheses of Group 5 Amide Amidinates and Their Reactions with Water: Different Reactivities of Nb(V) and Ta(V) Complexes

Nb Complexes

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