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The pentalene-ligated dysprosium complex [(η8-Pn†)Dy(Cp*)] (1Dy) (Pn† = [1,4-(iPr3Si)2C8H4]2−) and its magnetically dilute analogue are single-molecule magnets, with energy barriers of 245 cm−1. Whilst the [Cp*]− ligand in 1Dy provides a strong axial crystal field, the overall axiality of this system is attenuated by the unusual folded structure of the [Pn†]2− ligand. [ABSTRACT FROM AUTHOR]

Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] ( 1Dy Cpttt=1,2,4-tri( tert-butyl)cyclopentadienide) by the triethylsilylium cation produces the first base-free rare-earth metallocenium cation [(Cpttt)2Dy]+ ( 2Dy) as a salt of the non-coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [ 2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low-lying Kramers doublets correspond to a well-defined MJ value, with no significant mixing even in the higher doublets. [ABSTRACT FROM AUTHOR]

The structural and bonding properties of a three-coordinate N-heterocyclic silyene (NHSi) complex of the iron(ii) amide [Fe{N(SiMe3)2}2] are reported. Computational studies reveal that dispersion forces between the amido SiMe3 substituents and the isopropyl substituents on the NHSi ligand significantly enhance the stability of the complex, along with Fe-to-Si π-backbonding. [ABSTRACT FROM AUTHOR]

Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18-c-6 produces [{K(18-c-6)}HAN], which contains the S=1/2 radical [HAN].−. The [HAN].− radical can be transferred to the cobalt(II) amide [Co{N(SiMe3)2}2], forming [K(18-c-6)][(HAN){Co(N′′)2}3]; magnetic measurements on this compound reveal an S=4 spin system with strong cobalt-ligand antiferromagnetic exchange and J≈−290 cm−1 (−2 J formalism). In contrast, the CoII centres in the unreduced analogue [(HAN){Co(N′′)2}3] are weakly coupled (J≈−4.4 cm−1). The finding that [HAN].− can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on strongly coupled, triangular HAN building blocks. [ABSTRACT FROM AUTHOR]

Three-electron reduction of hexaazatrinaphthylene (HAN) with a magnesium(i) reagent leads to [(HAN){Mg(nacnac)}3] (1), containing a [HAN]3− ligand with a spin of S = 1/2. Ab initio calculations reveal that the [HAN]3− ligand in 1 has a ground-state wave function with multiconfigurational properties, and can be described as a triradicaloid species with a small amount of open-shell doublet character. [ABSTRACT FROM AUTHOR]

A synthetic route to magnesium guanidinate compounds that avoids ligand redistribution is reported; selected derivatives are active pre-catalysts in the dimerization of aldehydes. [ABSTRACT FROM AUTHOR]