Self‐Assembly of a 3d–5f Trinuclear Single‐Molecule Magnet from a Pentavalent Uranyl Complex

Abstract

Mixed-metal uranium compounds are very attractive candidates in the design of single-molecule magnets (SMMs), but only one 3d-5f hetero-polymetallic SMM containing a uranium center is known. Herein, we report two trimeric heterodimetallic 3d-5f complexes self-assembled by cationcation interactions between a uranyl(V) complex and a TPA-capped M II complex (M = Mn (1), Cd (2); TPA = tris(2-pyridylmethyl)amine). The metal centers were strategically chosen to promote the formation of discrete molecules rather than extended chains. Compound 1, which contains an almost linear {Mn À O = U = O À Mn} core, exhibits SMM behavior with a relaxation barrier of 81 AE 0.5 K-the highest reported for a mono-uranium system-arising from intramolecular Mn-U exchange interactions combined with the high Ising anisotropy of the uranyl(V) moiety. Compound 1 also exhibits an open magnetic hysteresis loop at temperatures less than 3 K, with a significant coercive field of 1.9 T at 1.8 K.Uranium compounds have been identified as attractive candidates in the search for new molecules displaying slow magnetic relaxation of a purely molecular origin (i.e. singlemolecule magnets, or SMMs). [1] The high magnetic anisotropy of the uranium ion over a range of oxidation states, combined

Evaluating f-Orbital Participation in the UV═E Multiple Bonds of [U(E)(NR2)3] (E = O, NSiMe3, NAd; R = SiMe3)

“…This control is especially relevant for U(V) complexes, as they are known to exhibit single-molecule magnet (SMM) behavior. 53,65 ■ EXPERIMENTAL SECTION General. All reactions and subsequent manipulations were performed under anaerobic and anhydrous conditions under an atmosphere of nitrogen.…”

Organometallic Neptunium Chemistry

“…33 Indeed, the recognition that f-block metal cations have high spin numbers and strong anisotropies has led to much research aimed at combining them into single molecule magnets, SMMs, molecules posessing an energetically isolated high-spin ground state that exhibit slow relaxation of the magnetic moment, and could have applications in spintronic devices. [34][35][36][37][38] Actinides are favored over lanthanides as the greater covalency in their bonding offers a greater chance of the control of directionality and stronger magnetic communication. The SMM properties of the actinocene sandwich Np(COT)2 is discussed in the section on COT complexes below.…”

Theoretical Investigation of the Electronic Structure and Magnetic Properties of Oxo-Bridged Uranyl(V) Dinuclear and Trinuclear Complexes

“…[23][24][25][26][27][28] These studies include mono [29][30][31][32][33][34][35][36][37][38] and polynuclear systems [39][40][41] and heteropolymetallic uranium-3d metal complexes. [42][43][44][45][46][47][48] Notably, uranium not only shows large spin-orbit coupling but in addition the more diffuse nature of 5f orbitals compared to 4f orbitals, 36,40 is expected to allow higher p-f orbital overlap and hence stronger magnetic couplings. 23,25 Therefore, efforts in this area have been directed to synthesize and characterize polynuclear uranium systems, where a successful strategy in promoting electronic interactions between 5f spin centers was to use covalently linked bridging ligands.…”