The THF-soluble [An(crypt)(OTf)2][OTf] complexes for An = Np and Pu were synthesized from AnI3(THF)4 starting materials based on pilot studies of the An = U system. 5f3 U(iii), 5f4 Np(iii), and 5f5 Pu(iii) electron configurations are indicated by DFT analysis of their UV-visible-NIR spectra.

The electrochemical properties of U­(III)-in-crypt (crypt = 2.2.2-cryptand) were examined in dimethylformamide (DMF) and acetonitrile (MeCN) to determine the oxidative stability offered by crypt as a ligand. Cyclic voltammetry revealed a U­(III)/U­(IV) irreversible oxidation at E PA= −0.49 V (vs Fe­(C5H5)2 +/0) in DMF and at E PA= −0.31 V (vs Fe­(C5H5)2 +/0) in MeCN. The electrochemistry of U­(III)-in-crypt complexes in the presence of water was also examined. These studies are supported by crystallographically characterized examples of U­(III)-in-crypt complexes as DMF, MeCN, and water adducts.

Lanthanide triflates have been used to incorporate NdIII and SmIII ions into the 2.2.2‐cryptand ligand (crypt) to explore their reductive chemistry. The Ln(OTf)3 complexes (Ln=Nd, Sm; OTf=SO3CF3) react with crypt in THF to form the THF‐soluble complexes [LnIII(crypt)(OTf)2][OTf] with two triflates bound to the metal encapsulated in the crypt. Reduction of these LnIII‐in‐crypt complexes using KC8 in THF forms the neutral LnII‐in‐crypt triflate complexes [LnII(crypt)(OTf)2]. DFT calculations on [NdII(crypt)]2+], the first NdII cryptand complex, assign a 4f4 electron configuration to this ion.

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The capacity of X-ray photoelectron spectroscopy (XPS) to provide information on the electronic structure of molecular organometallic complexes of Ln(II) ions (Ln = lanthanide) has been examined for the first time. XPS spectra were obtained on the air-sensitive molecular trivalent 4f n Cp′ 3 Ln III complexes (Ln = Sm, Eu, Gd, Tb; Cp′ = C 5 H 4 SiMe 3 ) and compared to those of the highly reactive divalent complexes, [K(crypt)]-[Cp′ 3 Ln II ] (crypt = 2.2.2-cryptand), which have either 4f n+1 (Sm, Eu) or 4f n 5d 1 electron configurations (Gd, Tb). The Ln 4d, Si 2p, and C 1s regions of the Ln(III) and Ln(II) complexes were identified and compared. The metal 4d peaks of these molecular lanthanide complexes were used diagnostically to compare oxidation states. The valence region of the Gd(III) and Gd(II) complexes was also examined with XPS and density function theory/random phase approximation (DFT/RPA) calculations, and this led to the tentative assignment of a signal from the 5d 1 electron consistent with a 4f 7 5d 1 electron configuration for Gd(II).