Evaluating Electron‐Transfer Reactivity of Complexes of Actinides in +2 and +3 Oxidation States by using EPR Spectroscopy

Abstract

The possibility that the relative reactivity of complexes of actinidem etalsi nt he + 2a nd + 3o xidation states could be investigated by examining reactions between An III and An II species of Th and Uw ithr are-earth metal reagents that provide EPR confirmation of electron transfer reactivity has been explored. 2 ). 1À ,r espectively, which wereidentified by EPR spectroscopy.The reverse reactions also occur which indicates that the reduction potentials are similar.[ Cp'' 3 La II ] 1À reduces Cp' 3 Y III and the reverse Y II /La III combination also occurs.I nb othc ases, the reactions generate EPR spectra indicative of multiple species in the mixtures of La II and Y II ,w hich is consistent with ligand exchange and demonstrates that numeroush eteroleptic complexes of these Ln II ions exist.Ar ecent development in rare-earth and actinide chemistry is the discovery that the + 2oxidation state is availableincrystallographically characterizable molecular speciesf or many more metals than was previously expected. Specifically, the first crystallographically-characterizable

Redox and structural properties of accessible actinide(ii) metallocalixarenes (Ac to Pu): a relativistic DFT study

“…13 When only considering the E 0 value, [U II L 2 ] would be synthetically accessible using similar approach in previous studies, as well as other actinide(II) complexes. [6][7][8][9][10][11][12][13][14][15][16][17][18][19] As seen in Fig. 2a, the trend obtained in the work is approximately the same as those of previous studies of Bratsch 27 and Nugent.…”

“…6 This extended uranium oxidation state to +II with respect to commonly recognized +III to +VI. Studies of the same group further had access to several U(II) complexes ligated by various substituted cyclopentadienyls (Cp) [7][8][9][10] and even a more electrondonating N(SiMe 3 ) 2 . 10 13 Interestingly, actinide(II) complexes such as Th, 14,15 Np [16][17][18] and Pu 19 have been synthetically accessible, most of which are accommodated by Cp-derived ligands.…”

“…[14][15][16][17]19 It is worth noting that aforementioned U(II) complexes have some similarity and difference. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Firstly, a lowtemperature synthetic route was developed by applying potassium graphite (KC 8 ) to reduce respective U(III) parent. Secondly, it is found that the stability of complex was partially contributed by d back-bonds between U and Ar/Cp.…”

Theoretical Probe for Tris(aryloxide)arene Complexed Low-valent Actinide Ions and Their Structural/Redox Properties

“…随后, 多个课题组先后合成几个二价铀配合物, 包括 Y•[UL E ] (L E ＝ [( Ad,Me ArOH) 3 mesitylene] 3-, Ad ＝ adamantyl) [8] 、 [U(NHAr iPr6 ) 2 ] (Ar iPr6 ＝ 2,6-(2,4,6-i Pr 3 C 6 H 2 ) 2 C 6 H 3 ) [9] 、 Y•[U{N(SiMe 3 ) 2 } 3 ] [10] 和[U(η 5 -C 5 i Pr 5 ) 2 ] [11] . 研究表明, 环戊二烯基(Cyclopentadienyl, Cp)配合物中铀的电子组 态为 5f 3 6d 1 , 而芳香基(Arene, Ar)的为 5f 4 [7,10,[12][13][14] . 另外, Cp 类配体还能稳定 Th [15] 、 Np [16,17] 和 Pu [18] 二价离子, 形 成的配合物基态电子组态分别为 6d 2 、5f 3 6d 1 和 5f 6 .…”

Single metal four-electron reduction by U(ii) and masked “U(ii)” compounds

“…Uranium( ii ) compounds could potentially effect four-electron transfer, but only very few examples of uranium in the +2 oxidation state have been reported so far 14 and their reactivity remains practically unexplored. 15 Indeed, the very low redox potential of the isolated U( ii ) complexes renders it difficult to control their reactivity, which can result in competitive one electron transfer reactions rather than multielectron transfer reactions. 10 b Conversely, complexes associating uranium in the +3 or +4 oxidation state to redox active ligands have proven effective in performing multielectron transfer reactions with a wide variety of substrates.…”