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Engineering the local dynamic environment is currently the major approach for preventing fast magnetization loss for single-molecule magnets (SMMs). It is hypothesized that the presence of fewer −CH3 which results in fewer C−H bonds, would reduce excitation energy loss via vibrations, but thus far, no experimental evidence clearly elaborates this effect. Moreover, although Gu and Wu proposed a vibronic barrier model to interpret the Raman process, the relationship between the barriers (\hbar\omega) and the molecular structure has not been explicitly correlated. Here, we use the trifluoromethyl group to systematically substitute the methyl groups in the axial position of the parental bis-butoxide pentagonal-bipyramidal dysprosium(III) SMM - [Dy(OtBu)2(py)5][BPh4]. The resulting complexes - [Dy(OLA)2py5][BPh4] (LA = CH(CF3)2− 1, CH2CF3− 2, CMe2CF3− 3)- show progressively enhanced TBhys (@100 Oe/s) from 17 K (for 3), 20 K (for 2) to 23 K (for 1). As the gradually enhanced averaged vibration energy generated by different axial ligands from 230 cm−1 (for 3), 257 cm−1 (for 2) to 321 cm−1 (for 1) was identified experimentally and theoretically to be the only variant that leads to this improvement, this finding unambiguously reveals, for the first time, the correlation between structural change and the multi two-phonon (Raman) relaxation processes in lanthanide-based SMMs and highlights the importance of controlling the relevant vibrations in building SMMs with higher blocking temperatures.

Although single-molecule magnets (SMMs) have been considered as the smallest entity to store binary information, the ability to retain the magnetization in one direction for more than 100 seconds is still below liquid nitrogen boiling point (77 K). One of the effective ways to enhance the magnetic blocking temperature is to couple the anisotropic magnetic centers in a proper manner. However, this has been only succeeded in the radical-bridged SMMs so far. For non-radical bridges the 100-second blocking temperature is still not seen. Here we report the best non-radical bridged dimeric SMM - {[Dy(OtBu)(4-NH2py)5]2(µ-Cl)}[BPh4]3 1 - with an energy barrier to magnetization reversal of 1302(6) K and 100-second blocking temperature near 8 K. Compared to the similar local C5v symmetric mononuclear complex [Dy(OtBu)Cl(py)5]BPh4 2, the much higher performance of dimeric 1 is attributed to the pseudo-D5h symmetry and "head-to-tail" linked Dy(III) principle magnetic via the collinear Dy‒Cl‒Dy exchange-coupling pathway.

Three six-coordinate Dy(III) single-molecule magnets (SMMs) [Dy(OtBu)2(L)4]+ with D4h local symmetry are obtained by optimising the equatorial ligands. Compound 1 where L = 4-phenylpyridine shows an energy barrier (Ueff) of 2075(11) K, which is the third largest Ueff, and the first Ueff > 2000 K for SMMs with axial-type symmetry so far.

We report herein a new cobalt(II/III) mixed-valence metal–organic framework formulated as [CoIICo2III(μ3-O)(bdc)3(tpt)]·guest 1, where bdc = benzene-1,4-dicarboxylate and tpt = 2,4,6-tri(4-pyridinyl)-1,3,5-triazine, which can be used as a redox-active heterogeneous catalyst for selective oxidation of cyclohexene on the allylic position without destroying the adjacent double bond. Two oxidants were chosen to demonstrate this result. For using tert-butyl hydroperoxide, the conversion rate is 63% and only allylic oxidation products (tert-butyl-2-cyclohexenyl-1-peroxide, 86%; 2-cyclohexen-1-one, 14%) are found, whereas if using O2 as oxidant, a total conversion of 38% is achieved and also only the allylic oxidation products (cyclohexenyl hydroperoxide, 72%; 2-cyclohexen-1-one, 20%; and cyclohex-2-en-1-ol, 8%) are found. The absence of any adduct on the double bond may be due to the unique radical chain mechanism triggered by the mixed-valent [CoIICo2III(μ3-O)] centers.

Dicarbollide ion, nido-C2B9H112- is isoelectronic with cyclopentadienyl. Here we make dysprosiacarboranes, namely [(C2B9H11)2Ln(THF)2][Na(THF)5] (Ln = Dy, 1Dy) and [(THF)3(μ-H)3Li]2[{η5-C6H4(CH2)2C2B9H9}Dy{η2:η5-C6H4(CH2)2C2B9H9}2Li] 3 and show that dicarbollide ligands impose strong magnetic axiality on the central Dy(III) ion. The effective energy barrier (Ueff) for loss of magnetisation can be varied by the substitution pattern on the dicarbollide. This is demonstrated by comparing complexes of nido-C2B9H112- and nido-[o-xylylene-C2B9H9]2- which show Ueff of 430(5) K and 804(7) K, respectively. The blocking temperature defined by the open hysteresis temperature of 3 reaches 6.8 K. Moreover, the linear complex [Dy(C2B9H11)2]- is predicted to have comparable SMM properties with linear [Dy(CpMe3)2]+ complex. As such, carboranyl ligands and its derivatives may open a new type of organometallic ligands for high-performance SMM design.

Local eight-coordination of the Dy(III) with D6h symmetry receives much expectation for high-performance single-molecule magnets (SMMs) due to the simultaneous fulfillment of the magnetic axiality and high coordination number (a requisite for the air stability). But the experimental realization is challenging due to the required restriction of six coordination atoms in the equatorial plane of the hexagonal-bipyramid, which is usually too crowded for the central Dy(III) ion. Here we show by using the hexaaza macrocyclic Schiff base ligand and fine-tuning the axial alkoxide/phenol type ligands, a family of hexagonal-bipyramidal Dy(III) complexes, namely [DyIII(L)(Cl)2(H2O/CH3OH)]Cl 1, [DyIII(L)(C6F5O)2(H2O)](BPh4)·2, [DyIII(L)(PhO)2](BPh4) 3, [DyIII(L)(4-MeO-PhO)2](BPh4) 4, [DyIII(L)(naPhO)2](BPh4) 5 and [DyIII(L)(Ph3SiO)2](BPh4) 6 , can be isolated. Among them, complexes 3, 4 and 5 possess nearly perfect D6h local symmetry. Complex 4 shows the highest effective magnetic reversal barrier 1338 K and an open hysteresis temperature 6 K at the field sweeping rate of 1.2 mT/s, which represents a new record for D6h SMMs.