Chemistry of polynuclear metal halides. IV. Electronic spectra of some niobium and tantalum M6X12n+ cluster derivatives

Fleming, Peter B.; McCarley, Robert E.

doi:10.1021/ic50088a011

Cited by 39 publications

(21 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5. Three absorption bands observed in the visible region of the spectrum of 1, with the maxima at 762, 868 and 963 nm, strongly substantiate a paramagnetic cluster compound with the [Ta 6 Br 12 ] 3+ cluster core [38][39][40]. The absence of any absorption in the region between 600 and 700 nm, where the [Ta 6 Br 12 ] 2+ cluster unit absorbs (Fig.…”

Section: Ir and Uv/vis Spectroscopymentioning

confidence: 65%

Synthesis, crystal structure, spectroscopic and thermal properties of [Et4N][Ta6Br12(H2O)6]Br4·4H2O (Et=ethyl)—A new compound with the paramagnetic [Ta6Br12]3+ cluster core

Perić¹,

Jozić²,

Planinić³

et al. 2009

Journal of Solid State Chemistry

View full text Add to dashboard Cite

Section: Ir and Uv/vis Spectroscopymentioning

confidence: 65%

Synthesis, crystal structure, spectroscopic and thermal properties of [Et4N][Ta6Br12(H2O)6]Br4·4H2O (Et=ethyl)—A new compound with the paramagnetic [Ta6Br12]3+ cluster core

Perić¹,

Jozić²,

Planinić³

et al. 2009

Journal of Solid State Chemistry

View full text Add to dashboard Cite

“…Also, n = 1 was observed for a relatively long time scale at a higher temperature (450~ based on exhaustive electrolysis (Table VII). Therefore, we conclude that the electron transfer reaction involved in this wave is the reduction of a Ta x+ species (believed to be TaCI$) to a Ta 4+ species Ta x+ + e-= Ta 4+ [3] for short time scales at 200-450~ and for long time scales at higher temperatures (>300~ The presence of a following chemical reaction is indicated by the shift of the peak potential of wave lc in the positive direction with increasing tantalum(V) concentration. Additional evidence is provided by normal pulse voltammetry.…”

Section: Discussionmentioning

confidence: 81%

Electrochemical Studies of Tantalum in Fluorochloroaluminate Melts at 200–450°C

Chen

Edwards

Mamantov

1993

J. Electrochem. Soc.

View full text Add to dashboard Cite

The electrochemistry of tantalum(V) species in sodium fluorochloroaluminate melts (10 mole percent NaF) has been investigated in the temperature range of 200 to 450~ using cyclic, normal pulse, and square wave voltammetries, exhaustive electrolysis, Raman and electronic spectroscopies, and x-ray diffraction methods. The electrochemical behavior of tantalum(V) is strongly dependent on temperature. Three main reduction waves are observed at a temperature of 300~ or higher. The first and second reduction waves merge into one wave at temperatures below 300~ The first reduction wave is associated with the reduction of tantalum(V) to tantalum(IV) Species followed by adimerization reaction which occurs very slowly at lower temperatures. The second reduction wave is believed to be the reduction of the tantalum(IV) dimer, Ta~ +, to a tantalum(III) species (probably Ta~+). The tantalum(III) species decomposes resulting in the formation of the cluster, Ta6CI~. The last reduction wave is assigned to the reduction of the trivalent tantalum species to a divalent tantalum species, which is highly unstable and decomposes to form the tantalum cluster, Ta~CI~L and metallic tantalum. The clusters are slowly reduced to metallic tantalum.The electrochemistry of tantalum is complicated by the existence of various compounds with different oxidation states, such as Ta 5 § Ta 4., Ta 3 § Ta~ ~ § Ta~ 4 § Ta ~ 1-4 in A1C13-NaC1 melts. 5' 8 McCarley et al. 2'3 reported that anhydrous low-valent tantalum halides can be synthesized by the reduction of tantalum(V) halides with aluminum metal at. appropriate temperatures. The electrolytic reduction and oxidation of tantalum and other refractory metal species in molten halide salts, 713 organic solvents, ~4 and room temperature me]ts~ have received considerable attention, since these metals generally have very high melting points and high corrosion resistance.We are interested in the electrochemistry and electroplating of refractory metals such as Nb, Ta, and W in alkali chloroaluminate and fluorochloroalumina-te melts. von Barner et al. 5 have recently reported electrochemical and spectroscopic studies of tantalum species in A1C13-NaC1 melts at 160-300~ Tantalum(V) forms two different species, TaCI~ and TaC15, in basic (A1ClJNaC1 mole ratio <1) and moderately acidic A1C13-NaC1 melts/' In addition, TaOC1; is formed in basic melts in the presence of small amounts of oxide ions. 5 The reduction of tantalum(V) in an acidic A1C13-NaC1 [51-49 mole percent (m/o)] melt at 175~ is believed to follow the sequence; Ta ~+ + e-= Ta 4., 2 Ta 4+ = Ta~ +, Ta~ § + 2e-= Ta~ +, 5 Ta~ + = Ta~ 4+ + 4 Ta% This reduction leads to the formation of a tantalum cluster. Formation of metallic tantalum was not observed in the electrolysis at 175~ in the sodium chloroaluminate melts.McCurry ~7 investigated the electrochemical behavior of tantalum(V) in A1C13-NaC1 melts saturated with NaCI, noted A1C13-NaCI~at melts, as a function of the oxide concentration in these melts. These studies resulted in a voltammetric method empl...

show abstract

“…The spectral and magnetic data of Field and Kepert (65) indicate the presence of the oxidized cluster, (Nb^C1^2)^*, as a contaminant of their solutions of (Nb^C1^2)^^ according to Fleming and McCarley,Schneider and Mackay (63) reported the electronic spectra of several (Nb^C1^2)^^ derivatives, however, the data for (Nb^C1^2)Cl^^ have been found to agree with that for, again, the oxidized derivative (Nb^C1^2)^* (64,66). Spreckelmeyer (66) has tabu lated data and reviewed the data of several other authors on the electronic absorption spectra of a number of species (M = Nb,Ta; X = CI,Br; n = 2,3,4), and (NbjFlz)^*.…”

Section: ° Hmentioning

confidence: 99%

“…Electronic Spectra of the Tantalum-Tungsten M5X22 Mixed Metal Cluster Compounds.-The determination of the electronic structure of the cluster compounds of niobium and tan talum has been the object of several previous studies (5,63,64,65,67). It was hoped that the substitution of one or more of the metal atoms in the cluster core would alter the elec tronic spectra of the cluster derivatives in such a way as to facilitate the definite assignment of at least some of the observed bands in the spectra.…”

Section: Synthesis Of Niobium-tungstenmentioning

confidence: 99%

A study of some metal cluster systems containing niobium, tantalum, molybdenum and tungsten

Dorman

View full text Add to dashboard Cite

Chemistry of polynuclear metal halides. IV. Electronic spectra of some niobium and tantalum M6X12n+ cluster derivatives

Cited by 39 publications

References 0 publications

Synthesis, crystal structure, spectroscopic and thermal properties of [Et4N][Ta6Br12(H2O)6]Br4·4H2O (Et=ethyl)—A new compound with the paramagnetic [Ta6Br12]3+ cluster core

Synthesis, crystal structure, spectroscopic and thermal properties of [Et4N][Ta6Br12(H2O)6]Br4·4H2O (Et=ethyl)—A new compound with the paramagnetic [Ta6Br12]3+ cluster core

Electrochemical Studies of Tantalum in Fluorochloroaluminate Melts at 200–450°C

A study of some metal cluster systems containing niobium, tantalum, molybdenum and tungsten

Contact Info

Product

Resources

About