Analysis of the Magnetic Exchange Interactions in Yttrium(III) Complexes Containing Nitronyl Nitroxide Radicals

Abstract

We report a combined theoretical and experimental investigation of the exchange interactions governing the magnetic behavior of a series of nitronyl-nitroxide (NIT)-based Y(III) complexes, i.e. Y(hfac) 3 (NIT-R) 2 with R = PhOPh (1), PhOEt (2) and PhOMe (3a, 3b). Even if some of these complexes or their Dy(III) parents were already 2

Construction and Magnetic Study of One‐Dimensional Lanthanide–Radical Chains Involving Pyridinone‐Substituted Nitronyl Nitroxide Radicals

“…For the radical ligand, the product of χ M T at room temperature is 0.346 cm 3 K mol –1 , which is in good agreement with the expected theoretical value of 0.375 cm 3 K mol –1 . Upon cooling, the χ M T value remains approximately constant until about 70 K, then decreases to 0.236 m 3 K mol –1 at 2 K. The 1/χ M versus T curve in the range of 2–300 K obeys the Curie–Weiss law, leading to C = 0.35 cm 3 K mol –1 and θ = –1.87 K, indicating the presence of a weak antiferromagnetic coupling between the NIT‐PhPyO ligands, which may result from the π ··· π interactions and the NO ··· ON contact, because the present NO ··· ON contact [4.220(1) Å] will produce weak antiferromagnetic coupling …”

Single-chain magnet behavior in a finite linear hexanuclear molecule

“…Indeed, the reliable determination of magnetic interactions on Ln-NIT compounds would require the use of state-of-the-art wave function-based calculations (CASSCF/DDCI) that are challenging even on isolated NIT-Y III -NIT molecules. 61 Moreover, the modelization of the magnetic interaction pathways is trickier here because SCM made of NIT radicals and lanthanide ions are known to host nearest (NIT-Ln) and next-nearest (Ln–Ln, and NIT–NIT) neighbor magnetic interactions, the latter being stronger than the former. 46 Last, the very large asymmetric unit of the hexanuclears (6 Tb III ions and five radicals) complicate further the study and does not allow for a reliable determination of all of the intramolecular magnetic interactions.…”

“…Accordingly, the very small dipolar coupling observed between Tb1 and Tb6 ions is unlikely to be strong enough to propagate a correlation length beyond the hexanuclears because it is several orders of magnitude smaller than the ones operating in the molecule as demonstrated on similar NIT-based compound. 37,[46][47][48]61 Accordingly, the divergence of the c M T at low temperature (Fig. 6) can be ascribed to the creation of a correlation length that is conned within each hexanuclear.…”

Magnetic Exchange Interaction in Nitronyl Nitroxide Radical-Based Single Crystals of 3d Metal Complexes: A Combined Experimental and Theoretical Study

“…43−50 Different computational methods have been employed to elucidate the mechanism of spin–spin interaction, the magnitude of effective exchange integrals, and the nature of the participating spin-active MOs. 46,47 The influence of the used basis set was emphasized in some of the studies. The model systems were excerpts from various experimentally obtained nitronyl nitroxide-based complexes with transition metal ions, which contained or did not contain unpaired electrons.…”