Coordination chemistry of lanthanides with cryptands. An X-ray and spectroscopic study of the complex Nd2(NO3)6 [C18H36O6N2]·H2O

Synthesis of LnII‐in‐Cryptand Complexes by Chemical Reduction of LnIII‐in‐Cryptand Precursors: Isolation of a NdII‐in‐Cryptand Complex

“…Thestructures of 4-Nd and 4-Sm are isomorphous.Both of these Ln II -in-crypt complexes have a1 0-coordinate tetracapped trigonal prismatic geometry as found for the Ln III -incrypt cations in 1-Nd and 1-Sm.T he average Nd-O(crypt) bond distance in 4-Nd is 0.13 longer than the average Nd-O(crypt) bond distance in 1-Nd.T he average Sm-O(crypt) bond distance in 4-Sm is 0.14 longer than that in 1-Sm, Table 2. Similarly,t he Nd-N(crypt) and Sm-N(crypt) bond distances are 0.13 and 0.14 longer than their counterparts in 1-Nd and 1-Sm,respectively.T he Nd-OTfand Sm-OTf bond distances in 4-Nd and 4-Sm are 0.19 longer than those in 1-Nd and 1-Sm,r espectively.T hese large differences in bond distances for 1-Nd/4-Nd and 1-Sm/4-Sm are consistent with 4f 4 and 4f 6 electron configurations for these Ln II ions. [21] Ty pically,r eduction of a4f 4 Ln III ion to a4f n 5d 1 Ln II causes an increase in bond distance of only 0.02-0.05 ,w hereas reduction to a4f n+1 Ln II ion causes an increase of 0.1 and larger.…”

Synthesis of LnII‐in‐Cryptand Complexes by Chemical Reduction of LnIII‐in‐Cryptand Precursors: Isolation of a NdII‐in‐Cryptand Complex

“…Table S3). Consistent with the 4f 4 assignment from the DFT calculations,t he extinction coefficients of 4-Nd are low (< 1000 m À1 cm À1 ). Forc omparison, the extinction coefficients of the previously reported Nd II complexes with assigned 4f 3 5d 1 electron configurations range from 4700 to as high as 5800 m À1 cm À1 .…”

“…[3] However,i nt he ensuing four decades,o nly seventeen crystallographically-characterized Ln-in-crypt complexes have been reported in the literature. [3][4][5][6][7][8][9][10][11][12][13] Themajority of these complexes involve lanthanides in the common + 3o xidation state and only recently have Ln II -in-crypt complexes been identified, but only for Ln = Sm, Eu, and Yb. [7][8][9][10][11][12] These crystallographically-characterized Ln II -in-crypt complexes were all formed from Ln II precursors, as shown in the examples in Equation (1) and (2), rather than by reduction of Ln III -in-crypt precursors.…”

Stabilization of U(III) to Oxidation and Hydrolysis by Encapsulation Using 2.2.2-Cryptand

“…The 2.2.2-cryptand ligand (crypt) has been studied extensively with alkali and alkaline earth metals. , Although an increasing number of examples with lanthanides are appearing in the literature, − only one paper has been published describing X-ray crystal structures of actinide crypt complexes . This is particularly surprising since solution studies of actinide crypt complexes have been present in the literature for many years. − The three structures previously reported by our group, [U­(crypt)­I 2 ]­I, 1-U , [U­(crypt)­I­(OH 2 )]­[I] 2 , 2-U , and [U­(crypt)­I­(OH 2 )]­[I]­[BPh 4 ], 3-U (eqs and ), all involve uranium in the +3 oxidation state.…”