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Out of the 14 lanthanide (Ln) ions, molecular complexes of Ln(IV) were known only for cerium and more recently terbium. Here we demonstrate that the +IV oxidation state is also accessible for the large praseodymium (Pr) cation. The oxidation of the tetrakis(triphenysiloxide) Pr(III) ate complex, [KPr(OSiPh3)(4)(THF)(3)], 1-Pr-Ph, with [N(C6H4Br)(3)][SbCl6], affords the Pr(IV) complex [Pr(OSiPh3)(4)(MeCN)(2)], 2-Pr-Ph, which is stable once isolated. The solid state structure, UV-visible spectroscopy, magnetometry, and cyclic voltammetry data along with the DFT computations of the 2-Pr-Ph complex unambiguously confirm the presence of Pr(IV).
David Lyndon Emsley, Dominik Józef Kubicki, Daniel Prochowicz, Amita Ummadisingu, Albert Hofstetter
Raffaella Buonsanti, Anna Loiudice, Jan Vávra, Petru Pasquale Albertini