Tantalum, easy as Pi: understanding differences in metal–imido bonding towards improving Ta/Nb separations

Weberg, Alexander B.; Chaudhuri, Sanjay; Cheisson, Thibault; Uruburo, Christian; Lapsheva, Ekaterina; Pandey, Pragati; Gau, Michael R.; Carroll, Patrick J.; Schatz, George C.; Schelter, Eric J.

doi:10.1039/d2sc01926d

Cited by 4 publications

(9 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The oxidation events associated with 1-Nb are all cathodically shifted ca. 100 mV compared to 1-Ta, and this difference in ligand-based oxidation events observed in this system was consistent with two previous reports of isostructural Nb/Ta complexes from our group, [Na(CH 16 which also showed ca. 100 mV differences between the Nb and Ta ligand oxidation features.…”

Section: Scheme 2 2-m-ox Synthetic Schemesupporting

confidence: 93%

“…Recent work from our groups showed a tantalum monoimido species, t BuN=(Nb/Ta)TriNOx 3− (TriNOx = [((2-t BuNO)C 6 H 4 CH 2 ) 3 N] 3− ), that displayed reactivity at the imido ligand, while no such reactivity was found for the isostructural niobium species. 16 We attributed this difference in reactivity to differences in frontier molecular orbital (FMO) contributions, showing that the HOMO/HOMO−1 of the tantalum species contained imido lone pair character, while the corresponding niobium orbitals lacked such features, allowing for selective reactivity and separation of the tantalum species. Hand, Lamb, Xue, and co-workers also showed an example of divergent Nb/Ta reactivity using a strongly pi-donating amidinate ligand.…”

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Observing Similarities and Differences in the Properties of Isostructural Niobium(V)/Tantalum(V) Coordination Compounds with Strong Pi-Donor Ligands

Furigay,

Chaudhuri,

et al. 2023

Inorg. Chem.

Self Cite

View full text Add to dashboard Cite

While niobium and tantalum are found together in their mineral ores, their respective applications in technology require chemical separation. Nb/Ta separations are challenging due to the similar reactivities displayed by these metals in the solution phase. Coordination complexes of these metals have been studied in the contexts of catalysis, smallmolecule activation, and functional group insertion reactivity; relatively few studies exist directly comparing the properties of isostructural Nb/Ta complexes. Such comparisons advance the development of Nb/Ta separation chemistry through the potential for differential reactivity. Here, we explore fundamental physicochemical properties in extensively characterized Nb/Ta coordination complexes [Na(DME) 3 ][MClamp], (Clamp 6− = tris-(2-(3′,5′-di-tert-butyl-2′oxyphenyl)amidophenyl)amine; M = Nb, Ta) to advance the understanding of the different electronic, optical, and excited-state properties that these metals exhibit in pi-loaded coordination complexes.

show abstract

Section: Scheme 2 2-m-ox Synthetic Schemesupporting

confidence: 93%

Section: ■ Introductionmentioning

confidence: 99%

Observing Similarities and Differences in the Properties of Isostructural Niobium(V)/Tantalum(V) Coordination Compounds with Strong Pi-Donor Ligands

Furigay,

Chaudhuri,

et al. 2023

Inorg. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…This is particularly surprising given the prevalence of various other niobium(IV) ,,, and niobium(III) − , imido complexes, together with the fact that the first niobium NHC complex was based on niobium(IV), Also, Marchetti and co-workers have recently isolated bis - NHC adducts of niobium(IV)-oxo complexes (Figure F) . However, the large stabilization of the niobium(V) oxidation state compared to analogous vanadium(V) complexes might also be interesting for future separation strategies of these two elements via their (redox)-properties. − It is worth mentioning at this point that regardless of the solvents (toluene or THF) and synthetic strategies used ( Li 2 L 1 or [H 3 L 1 ][Cl] /NEt 3 ), the use of NbCl 5 did not meet with any success to form a heteroleptic Nb(V) chloride complex and no NHC complexes could be isolated or identified from the crude reactions mixtures.…”

Section: Resultsmentioning

confidence: 99%

Reactivity and Structure of a Bis-phenolate Niobium NHC Complex

et al. 2022

View full text Add to dashboard Cite

We report the facile synthesis of a rare niobium(V) imido NHC complex with a dianionic OCO-pincer benzimidazolylidene ligand (L 1 ) with the general formula [NbL 1 (N t Bu)PyCl] 1-Py. We achieved this by in situ deprotonation of the corresponding azolium salt [H 3 L 1 ][Cl] and subsequent reaction with [Nb(N t Bu)Py 2 Cl 3 ]. The pyridine ligand in 1-Py can be removed by the addition of B(C 6 F 5 ) 3 as a strong Lewis acid leading to the formation of the pyridine-free complex 1. In contrast to similar vanadium(V) complexes, complex 1-Py was found to be a good precursor for various salt metathesis reactions, yielding a series of chalcogenido and pnictogenido complexes with the general formula [NbL 1 (N t Bu)Py(EMes)] (E = O (2), S (3), NH (4), and PH (5)). Furthermore, complex 1-Py can be converted to alkyl complex (6) with 1 equiv of neosilyl lithium as a transmetallation agent. Addition of a second equivalent yields a new trianionic supporting ligand on the niobium center (7) in which the benzimidazolylidene ligand is alkylated at the former carbene carbon atom. The latter is an interesting chemically "noninnocent" feature of the benzimidazolylidene ligand potentially useful in catalysis and atom transfer reactions. Addition of mesityl lithium to 1-Py gives the pyridine-free aryl complex 8, which is stable toward "overarylation" by an additional equivalent of mesityl lithium. Electrochemical investigation revealed that complexes 1-Py and 1 are inert toward reduction in dichloromethane but show two irreversible reduction processes in tetrahydrofuran as a solvent. However, using standard reduction agents, e.g., KC 8 , K-mirror, and Na/Napht, no reduced products could be isolated. All complexes have been thoroughly studied by various techniques, including 1 H-, 13 C{ 1 H}-, and 1 H-15 N HMBC NMR spectroscopy, IR spectroscopy, and X-ray diffraction analysis.

show abstract

“…[7] For example, such imido complexes have been explored towards the electrochemical separation of Nb and Ta. [8] On the other side, the reactivity at the imido center can be drastically enhanced, if a second π-donor ligand (e. g. another imido or oxo ligand) is introduced. The enhanced reactivity within these system is closely related to strong π-loading effects, weakening the overall strength of the metal-imido multiple bond.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the higher stability of the imido ligand in group V and VI compared to group IV metals, the construction of complexes with sophisticated and specifically tailored properties is possible [7] . For example, such imido complexes have been explored towards the electrochemical separation of Nb and Ta [8] . On the other side, the reactivity at the imido center can be drastically enhanced, if a second π‐donor ligand (e. g. another imido or oxo ligand) is introduced.…”

Section: Introductionmentioning

confidence: 99%

A Versatile Comproportionation Route to Construct Mono‐Imido Trichlorido Complexes of Molybdenum(V) and Tungsten(V)

Leitner,

Wurst,

Hohloch

2024

Zeitschrift anorg allge chemie

View full text Add to dashboard Cite

We report the facile and high‐yielding multi‐gram synthesis of pentavalent heavy group VI mono‐imido complexes with the general formula M(NR)Cl3Ln (M = Mo, W, R = Aryl or Alkyl, L = DME n = 1 or Py n =2) following a comproportionative imido group transfer procedure starting from the corresponding bis‐imido complexes and MCl4. The procedure works well for both aryl and alkyl imido ligands, in the case of molybdenum but only for alkyl imidos in the case of tungsten. Overall, five mono‐imido complexes have been structurally characterized and purity is established by elemental analysis and EPR spectroscopy.

show abstract

Tantalum, easy as Pi: understanding differences in metal–imido bonding towards improving Ta/Nb separations

Abstract: The separation and purification of niobium and tantalum, which co-occur in natural sources, is difficult due to their similar physical and chemical properties. The current industrial method for separating Ta/Nb...

Cited by 4 publications

References 68 publications

Observing Similarities and Differences in the Properties of Isostructural Niobium(V)/Tantalum(V) Coordination Compounds with Strong Pi-Donor Ligands

Observing Similarities and Differences in the Properties of Isostructural Niobium(V)/Tantalum(V) Coordination Compounds with Strong Pi-Donor Ligands

Reactivity and Structure of a Bis-phenolate Niobium NHC Complex

A Versatile Comproportionation Route to Construct Mono‐Imido Trichlorido Complexes of Molybdenum(V) and Tungsten(V)

Contact Info

Product

Resources

About