High-Spin Molecules: Unusual Magnetic Susceptibility Relaxation Effects in [Mn12O12(O2CEt)16(H2O)3] (S = 9) and the One-Electron Reduction Product (PPh4)[Mn12O12(O2CEt)16(H2O)4] (S = 19/2)

Modulating the magnetic relaxation of lanthanide-based single-molecule magnets

“…In fact, the Er-based phthalocyanine complex shows no slow relaxation phenomenon, with the low-lying ground states of m J = ±1/2. Interestingly, through the fitting of the susceptibility data of [ErW 10 O 36 ] 9− , a high Kramers doublet ground state with m J = ±13/2 is present. Possibly it is their hair-like geometrical differences that bring the changes to the LF parameters of a single lanthanide ion, resulting in the distinct magnetization properties for two types of sandwich-like complexes.…”

“…It has been nearly twenty years since the first discovery that the Mn 12 cluster with a bistable ground state shows slow magnetic relaxation. Initially, most efforts were dedicated to obtaining high-spin, strongly-coupled transition-metal SMMs such as the Mn 12 derivatives [9,10] and Fe 8 iron complexes [11]. However, theoretical study based on experiments suggests that large magnetic anisotropy is not helped by a high spin state of the ground state for transition-metal systems, which has been a crucial roadblock to obtaining systems with larger energy barriers [12,13].…”

“…However, theoretical study based on experiments suggests that large magnetic anisotropy is not helped by a high spin state of the ground state for transition-metal systems, which has been a crucial roadblock to obtaining systems with larger energy barriers [12,13]. Nevertheless, since Ishikawa et al [14] discovered lanthanide double-decker complexes [Pc 2 Ln] − TBA + (Ln = Tb III , Dy III , Ho III ; TBA + = N(C 4 H 9 ) + ) functioning as very efficient SMMs, the complexes containing lanthanide elements are highlighted and large numbers of Lanthanide-based Single Molecule Magnets (Ln-SMMs) with larger energy barriers have evolved, especially Dy-based complexes with various nuclearities from Dy 1 [15], Dy 2 [16,17], Dy 3 [18,19], Dy 4 [20,21], Dy 6 [22], Dy 10 [23] to Dy 26 [24]. These systems may hold the key to obtaining high anisotropic barrier single-molecule magnets (SMMs).…”

Anisotropy barrier reduction in fast-relaxingMn12single-molecule magnets

“…[1][2][3] Of particular recent interest has been the synthesis and investigation of polynuclear transition metal complexes, so-called Single-Molecule Magnets (SMMs), 4 which have been shown to exhibit a range of fascinating quantum effects, including quantum magnetization tunneling (QMT) 5,6 and magnetic quantum phase interference. 7,8 Around the same time as the first clear-cut observations of resonant QMT 5,6 in [Mn 12 12 Ac for short), 9 it was found that typical single-crystal samples contain a significant fraction (up to 10%) of fast relaxing (FR) species, 10 i.e. a minority of molecules that relax much faster than the majority slow relaxing (SR) species at a given temperature.…”

“…These FR species may be identified from magnetic measurements in a variety of ways. First of all, they exhibit a peak in the out-of-phase ac susceptibility, χ˝, in the 23 K range (at 1 kHz), [10][11][12][13] as opposed to the dominant peak in the 67 K range associated with the majority SR species, i.e. the blocking temperature, T B , associated with the FR species is considerably lower (T B,FR < 2 K) than for the SR molecules (T B,SR ~ 4 K).…”