We report a monometallic dysprosium complex, [Dy(O Bu) (py) ][BPh ] (5), that shows the largest effective energy barrier to magnetic relaxation of U =1815(1) K. The massive magnetic anisotropy is due to bis-trans-disposed tert-butoxide ligands with weak equatorial pyridine donors, approaching proposed schemes for high-temperature single-molecule magnets (SMMs). The blocking temperature, T , is 14 K, defined by zero-field-cooled magnetization experiments, and is the largest for any monometallic complex and equal with the current record for [Tb N {N(SiMe ) } (THF) ].

Understanding quantum tunnelling of the magnetisation (QTM) in single-molecule magnets (SMMs) is crucial for improving performance and achieving molecule-based information storage above liquid nitrogen temperatures. Here, through a field- and temperature-dependent study of the magnetisation dynamics of [Dy(tBuO)Cl(THF)5][BPh4]·2THF, we elucidate the different relaxation processes: field-independent Orbach and Raman mechanisms dominate at high temperatures, a single-phonon direct process dominates at low temperatures and fields >1 kOe, and a field- and temperature-dependent QTM process operates near zero field. Accounting for the exponential temperature dependence of the phonon collision rate in the QTM process, we model the magnetisation dynamics over 11 orders of magnitude and find a QTM tunnelling gap on the order of 10−4 to 10−5 cm−1. We show that removal of Dy nuclear spins does not suppress QTM, and argue that while internal dipolar fields and hyperfine coupling support QTM, it is the dynamic crystal field that drives efficient QTM.

Single-molecule magnets (SMMs) could potentially store binary information in future ultra-high-density information storage devices. The current challenge to improve performance is understanding and preventing memory loss via molecular vibrations. In this work, we synthesize an improved SMM over a previous design and use a computational approach to probe how molecular vibrations contribute to memory loss.

Although the development of single‐molecule magnets (SMMs) is rapid, there are only two families of high energy barrier (Ueff) dysprosium(III) SMMs known so far: the cyclopentadienyl (Cp) family with a sandwich structure and the pentagonal‐bipyramidal (PB) family with D5h symmetry. These high‐barrier SMMs, which usually possess Ueff>500 cm−1 allow the separate study of the four magnetic relaxation paths, namely, direct, quantum tunnelling, Raman and Orbach processes, in detail. Whereas the first family is chemically more challenging to modify the Cp rings, it is shown herein that the latter family, with the common formulae [DyX1X2(Leq)5]+, such as X1/X2=−OCMe3, −OSiMe3, −OPh, Cl− or Br−; Leq=THF/pyridine/4‐methylpyridine, can be readily fine‐tuned with a range of axial and equatorial ligands by simple substitution reactions. This allows unambiguous confirmation that the Ueff mainly depends on the identity of X1 and X2, rather than on Leq. More importantly, the fitted parameters are barrier dependent. If X1 is an O donor and X2 is a halide, 500

A series of electron-accepting chalcogen-bridged viologens with narrow HOMO-LUMO bandgaps and low LUMO levels is reported. The optoelectronic properties of chalcogenoviologens can be readily tuned through heavy atom substitution (S, Se and Te). Herein, in situ electrochemical spectroscopy was performed on the proof-of-concept electrochromic devices (ECD). E-BnV (E=Se, Te; BnV =benzyl viologen) was used for the visible-light-driven hydrogen evolution due to the strong visible-light absorption. Remarkably, E-BnV was not only used as a photosensitizer, but also as an electron mediator, providing a new strategy to explore photocatalysts. The higher apparent quantum yield of Se-BnV could be interpreted in terms of different energy levels, faster electron-transfer rates and faster formation of radical species.

Convenient silylborane precursors for introducing N,B-bidentate boryl ligands onto transition metals were designed, prepared, and employed in ready formation of irdium(III) complexes via Si-B oxidative addition. A practical, efficient catalytic ortho-borylation reaction of arenes with a broad range of directing groups was developed using an in situ generated catalyst from the silylborane preligand 3c and [IrCl(COD)].

We report a study of quantum tunneling of the magnetisation in three Dy(iii) single-molecule magnets.

Three six‐coordinate DyIII single‐molecule magnets (SMMs) [Dy(OtBu)2(L)4]+ with local D4h symmetry are obtained by optimizing the equatorial ligands. One of the compounds with 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. Ab initio analysis indicates that the exceptional uniaxial magnetic anisotropy is deeply related to the axially compressed octahedral geometry. This work provides a new insight into the local D4h symmetry for high‐performance SMMs.