Organometallic single-molecule magnet: Studies of two dimeric organometallic dysprosium compounds reveal one to be the first organometallic single-molecule magnet (see picture). A comparison of the magnetic properties and electronic structures of the two compounds shows that Dy⋅⋅⋅Dy interactions have a profound influence on the dynamic magnetic behaviour, while having little effect on the static magnetic measurements.
[Cp(2)Dy(thf)(μ-Cl)](2) (2) was synthesized from [Cp(2)Dy(μ-Cl)](n), which crystalizes as two polymorphs, with n = 2 (1a) or ∞ (1b). All three compounds show slow relaxation of magnetization, and in 2 the quantum tunnelling was found to be exchange-biased.
Metallation of hexahydropyrimidopyrimidine (hppH) by [Fe{N(SiMe(3))(2)}(2)] (1) produces the trimetallic iron(II) amide cage complex [{(Me(3)Si)(2)NFe}(2)(hpp)(4)Fe] (2), which contains three iron(II) centers, each of which resides in a distorted tetrahedral environment. An alternative, one-pot route that avoids use of the highly air-sensitive complex 1 is described for the synthesis of the iron(II)-lithium complex [{(Me(3)Si)(2)N}(2)Fe{Li(bta)}](2) (3) (where btaH = benzotriazole), in which both iron(II) centers reside in 3-coordinated pyramidal environments. The structure of 3 is also interpreted in terms of the ring laddering principle developed for alkali metal amides. Magnetic susceptibility measurements reveal that both compounds display very weak antiferromagnetic exchange between the iron(II) centers, and that the iron(II) centers in 2 and 3 possess large negative axial zero-field splittings.
The structures of alkali metal complexes of silyl-substituted ansa-tris (allyl) [endo,exo] stereochemistries. The trisodium complex [L 2 Na{Na-(tmeda)} 2 ] 2 (6) consists of a hexa(allylsodium) macrocycle that aggregates as a result of cation-π interactions between the phenyl substituents and the sodium cations. An attempt to prepare the tripotassium complex of L 1 resulted in the formation of the bimetallic potassium/lithium complex
The one-pot reactions of the tin(II) halides SnX 2 (X = F, Cl, Br, I) with lithium hexamethyldisilazide, [Li(hmds)], and benzotriazole, (bta)H, produce contrasting outcomes.
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