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.
Taming salophen in rare earth metallocene chemistry
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.
- Award ID(s):
- 1919565
- Publication Date:
- NSF-PAR ID:
- 10346983
- Journal Name:
- Inorganic Chemistry Frontiers
- Volume:
- 9
- Issue:
- 7
- Page Range or eLocation-ID:
- 1325 to 1336
- ISSN:
- 2052-1553
- Sponsoring Org:
- National Science Foundation
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