Spectroscopic and magnetic investigations of actinide‐based nanomagnets

Abstract

Magnetic exchange is an essential feature of transition-metal nanomagnets because it combines the relatively low spin-only moments of several ions into a "giant spin" ground state, which can make slow magnetic relaxation very favorable in an axially anisotropic environment. In contrast, most of the early research on lanthanidebased complexes focused on single-ion magnets, where the required large moment is generated by the unquenched orbital contribution (which is parallel to the spin in heavy rare earths). With their unfilled 5f electronic shell being on the verge between localization and itinerancy, actinides are expected to combine the best of both 3d and 4f metals in terms of exchange and anisotropy, and are therefore under consideration as potential building blocks for the next generation of single-molecule magnets. In this Perspective, a review of the recent development in this field is given, and some discrepancies between the spectroscopic and magnetic data are discussed.

DFT Investigations of the Magnetic Properties of Actinide Complexes

“…During recent decades, the magnetochemistry of actinide complexes has gained an important impetus, not only at the experimental level, but also at the theoretical one [1][2][3][4][5][6][7][8]. Indeed, since the first observation early in the 1990s of the antiferromagnetic (AF) coupling between uranium(V) centers in the para-imido [(MeC 5 H 4 ) 3 U] 2 (µ-1,4-N 2 C 6 H 4 ) complex by Rosen et al [9], this class of binuclear actinide systems has been arousing interest .…”

A Mononuclear Uranium(IV) Single‐Molecule Magnet with an Azobenzene Radical Ligand

“…[1,5] However,i n2 003 seminalw ork by Ishikawa and coworkers revealed that bis-phthalocyanine lanthanide(III) compounds containing as inglep aramagnetic ion, Tb or Dy,e xhibited SMM behaviour as well. [10] Sincet hen, an increasing number of SMMs based on mononuclearl anthanide compounds [5,[11][12][13][14] and,m ore recently,m ononuclear actinide [5,[15][16][17][18] and transition-metal complexes [5,19] have been reported. These compounds are generally known as single-ionm agnets (SIMs).…”

“…Thus, they can be considered to be better candidates to provide SIMs than lanthanides, as the J ground-state splitting caused by the ligand field is expected to be larger. [15,18] Although some examples have been reportedi n the last few years, SIMsb ased on actinides are still scarce and mainly restricted to U III species;a side from af ew distinct compounds, [16,17,26,27] most studies have focusedo np oly(pyrazolyl)borate uranium complexes. [28][29][30][31][32][33][34][35][36] These studies on wisely selected compounds could clearly evidence the effects of axial [27-29, 32-34, 36] and non-axial ligand environments, [16,17,27,31,35] magnetic dilution, [30] charge of the coligand, [31,35] different ligand donor strength in the same trigonal-prismatic [34] and tetrahedral [16] coordination geometries and also the first comparative studies with isostructurallanthanide complexes.…”

Future Directions for Transuranic Single Molecule Magnets

“…SMM behaviour has actually been observed in several monometallic U III [13] and U V [14] complexes and in heterometallic coordination compounds containing U V and either Mn II or Dy III cations [15][16][17]. The results obtained on these systems have been the subject of recent reviews [12,[18][19][20]. Here, we will critically summarize the attempts to obtain SMMs based on transuranic elements, mainly Np and Pu, focusing on the reasons for the limited success obtained so far and trying to indicate a possible direction for future research.…”

“…The results obtained on these systems have been the subject of recent reviews [12,[18][19][20]. Here, we will critically summarize the attempts to obtain SMMs based on transuranic elements, mainly Np and Pu, focusing on the reasons for the limited success obtained so far and trying to indicate a possible direction for future research.…”