skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Spectroscopic and electrochemical characterization of a Pr 4+ imidophosphorane complex and the redox chemistry of Nd 3+ and Dy 3+ complexes
Title: Spectroscopic and electrochemical characterization of a Pr 4+ imidophosphorane complex and the redox chemistry of Nd 3+ and Dy 3+ complexes
The molecular tetravalent oxidation state for praseodymium is observed in solution via oxidation of the anionic trivalent precursor [K][Pr 3+ (NP(1,2-bis- t Bu-diamidoethane)(NEt 2 )) 4 ] (1-Pr(NP*)) with AgI at −35 °C. The Pr 4+ complex is characterized in solution via cyclic voltammetry, UV-vis-NIR electronic absorption spectroscopy, and EPR spectroscopy. Electrochemical analyses of [K][Ln 3+ (NP(1,2-bis- t Bu-diamidoethane)(NEt 2 )) 4 ] (Ln = Nd and Dy) by cyclic voltammetry are reported and, in conjunction with theoretical modeling of electronic structure and oxidation potential, are indicative of principal ligand oxidations in contrast to the metal-centered oxidation observed for 1-Pr(NP*). The identification of a tetravalent praseodymium complex in in situ UV-vis and EPR experiments is further validated by theoretical modeling of the redox chemistry and the UV-vis spectrum. The latter study was performed by extended multistate pair-density functional theory (XMS-PDFT) and implicates a multiconfigurational ground state for the tetravalent praseodymium complex.  more » « less
Award ID(s):
1943452
PAR ID:
10341736
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Dalton Transactions
Volume:
51
Issue:
17
ISSN:
1477-9226
Page Range / eLocation ID:
6696 to 6706
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Inorganic Chemistry Frontiers)
    A series of multinuclear metallocenes composed of a t Bu salophen dianion bound to two rare earth metal ions, where each is encased in a bis-pentamethylcyclopentadienyl scaffold, was realized. The isolated molecules (Cp* 2 RE) 2 (μ- t Bu salophen), where RE = Gd (1), Dy (2), and Y (3), constitute the first salophen-bridged metallocene complexes for any metal ion. 1–3 were characterised by X-ray crystallography, cyclic voltammetry, IR, NMR, and UV-Vis-NIR spectroscopy. Cyclic voltammograms of 1–3 excitingly exhibit quasi-reversable features attributed to the ( t Bu salophen 2− / t Bu salophen 3− ˙) redox couple. DFT calculations on 3 uncovered the highest occupied molecular orbital to be primarily localized on the metallocene and phenolate moieties of the t Bu salophen ligand. Furthermore, the nuclear spin I = ½ for yttrium allowed the collection of 89 Y NMR spectra for 3. Magnetic studies revealed slow magnetic relaxation, placing 2 among dysprosocenium-based single-molecule magnets containing a doubly anionic ligand in the equatorial plane. 
    more » « less
  2. ; ; ; (, Inorganic Chemistry)
    The use of redox-active ligands with the f-block elements has been employed to promote unique chemical transformations and explore their unique emergent electronic properties for a myriad of applications. In this study, we report eight new tris(amido) metal complexes: 1–Ln (Ln = Tb3+, Dy3+, Ho3+, Er3+, Tm3+, and Yb3+), 1–La, and 1–Ti (an early transition metal analogue). The one-electron oxidation of the tris(amido) ligand was conducted to generate semi-iminato complexes 2–Ln, 2–La, and 2–Ti, and these complexes were studied using EPR. Tris(amido) complexes 1–Ln, 1–La, and 1–Ti were fully characterized using a range of spectroscopic (NMR and UV–vis/NIR) and physical techniques (X–ray diffraction and cyclic voltammetry, with the exception of 1–La). Computational methods were employed to further elucidate the electronic structures of these complexes. Lastly, complexes 1–Ln, 1–La, and 1–Ti were probed as catalysts for alkyl–alkyl cross-coupling, and the initial rate of the reaction was measured to explore the influence of the metal ion. 
    more » « less
  3. ; ; ; (, European Journal of Inorganic Chemistry)
    Abstract A new series of mono‐ and bis‐alkynyl CoIII(TIM) complexes (TIM=2,3,9,10‐tetramethyl‐1,4,8,11‐tetraazacyclotetradeca‐1,3,8,10‐tetraene) is reported herein. Thetrans‐[Co(TIM)(C2R)Cl]+complexes were prepared from the reaction betweentrans‐[Co(TIM)Cl2]PF6and HC2R (R=tri(isopropyl)silyl or TIPS (1), ‐C6H4‐4‐tBu (2), ‐C6H4‐4‐NO2(3 a), andN‐mesityl‐1,8‐naphthalimide or NAPMes(4 a)) in the presence of Et3N. The intermediate complexes of the typetrans‐[Co(TIM)(C2R)(NCMe)](PF6)(OTf),3 band4 b, were obtained by treating3 aand4 a, respectively, with AgOTf in CH3CN. Furthermore, bis‐alkynyltrans‐[Co(TIM)(C2R)2]PF6complexes,3 cand4 c, were generated following a second dehydrohalogenation reaction between3 band4 b, respectively, and the appropriate HC2R in the presence of Et3N. These new complexes have been characterized using X‐ray diffraction (2,3 a,4 a, and4 c), IR,1H NMR, UV/Vis spectroscopy, fluorescent spectroscopy (4 c), and cyclic voltammetry. 
    more » « less
  4. ; ; ; ; ; (, Journal of The Electrochemical Society)
    Increasing lanthanide demand to support clean energy goals drives the need to develop more efficient approaches to separate adjacent lanthanides. Most approaches for lanthanide separations are not very selective and are based on small differences in lanthanide ionic radii. Concentrated potassium carbonate media has shown some potential to enable oxidation of praseodymium (Pr) and terbium (Tb) to their tetravalent states, which could ultimately enable a separation based on differences in oxidation states, but very little is known regarding the system’s chemistry. This work completes a detailed examination of cerium (Ce) redox chemistry in concentrated carbonate media to support the development of Pr and Tb oxidation studies. The half-wave potential (E 1/2 ) of the Ce(III)/(IV) redox couple is evaluated under various solution conditions and computational modeling of carbonate coordination environments is discussed. Cyclic voltammetry shows higher carbonate concentrations and temperatures can lower the potential required to oxidize Ce(III) by 54 mV (3.5 to 5.5 M) and 39 mV (from 10 °C to 70 °C). Chronoabsorptometry shows Ce(III) and Ce(IV) carbonate complexes are chemically stable and reversible. Computational modelling suggests the most likely coordination environment for the Ce(IV) complex is Ce(CO 3 ) 4 (OH) 5− which is less entropically favorable than the lowest energy Ce(III) complex, Ce(CO 3 ) 4 5− . 
    more » « less
  5. ; ; (, Dalton Transactions)
    The reduction potentials (reported vs. Fc + /Fc) for a series of Cp′ 3 Ln complexes (Cp′ = C 5 H 4 SiMe 3 , Ln = lanthanide) were determined via electrochemistry in THF with [ n Bu 4 N][BPh 4 ] as the supporting electrolyte. The Ln( iii )/Ln( ii ) reduction potentials for Ln = Eu, Yb, Sm, and Tm (−1.07 to −2.83 V) follow the expected trend for stability of 4f 7 , 4f 14 , 4f 6 , and 4f 13 Ln( ii ) ions, respectively. The reduction potentials for Ln = Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu, that form 4f n 5d 1 Ln( ii ) ions ( n = 2–14), fall in a narrow range of −2.95 V to −3.14 V. Only cathodic events were observed for La and Ce at −3.36 V and −3.43 V, respectively. The reduction potentials of the Ln( ii ) compounds [K(2.2.2-cryptand)][Cp′ 3 Ln] (Ln = Pr, Sm, Eu) match those of the Cp′ 3 Ln complexes. The reduction potentials of nine (C 5 Me 4 H) 3 Ln complexes were also studied and found to be 0.05–0.24 V more negative than those of the Cp′ 3 Ln compounds. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email