Magnetocaloric effect in a high-spin ferromagnetic molecular cluster.

The reaction of MnCl·4HO with HL ((1-methyl-1H-imidazol-2-yl)methanol) and pdH (1, 3 propanediol) in a basic MeCN solution results in the formation of a mixed-valence [Mn] cationic cluster and two [MnCl] counter anions. The metallic skeleton of the cluster describes two geometrically equivalent mixed-valent, linked [Mn Mn ] supertetrahedra in which nearest-neighbor metal ions have a different oxidation state. Magnetic susceptibility, magnetization data and heat capacity measurements support evidence of predominant ferromagnetic correlations, leading to a = 22 spin ground state for the [Mn Mn ] supertetrahedra, which are pair-linked by a weak antiferromagnetic coupling.

Tracking the conical intersection dynamics for the photoinduced Jahn-Teller switch of a Mn(iii) complex.

Octahedral Mn(iii) ions predominantly exhibit an axially elongated Jahn-Teller (JT) distortion, which is responsible for their large uniaxial magnetic anisotropy. As a result, they are often used in the synthesis of single-molecule magnets (SMMs). Modulation of the JT distortion using femtosecond laser pulses could offer a route to controlling the magnetisation direction, and therefore is promising for the development of data storage devices that work on ultrafast timescales.

Tetra-, tetradeca- and octadecametallic clusters of Mn.

Reaction of equimolar amounts of MnBr·4HO and HL ((3,5-dimethyl-1-pyrazol-1-yl)methanol) in a basic MeCN solution leads to the formation of [MnII4(L)Br(HO)] (1), whose metallic skeleton is a [MnII4] tetrahedron and cluster core a [MnII4(μ-O)] cubane. Replacing MnBr·4HO with Mn(OCMe)·4HO affords [MnIII2MnII12O(L)(OAc)] (2) which is best described as a series of edge-sharing [Mn] tetrahedra that have self-assembled into a linear array in which each [Mn] pair is 'twisted' with respect to its neighbours in a corkscrew-like manner. Employment of the triangle [MnIII3O(OAc)(py)](ClO) as a reactant instead of a Mn salt results in the formation of [MnIII14MnII4O(L)(HL)(OAc)(HO)] (3) whose core is comprised of three vertex-sharing [MnIII4] butterflies flanked on either side by one [MnIII4] cubane and one [MnIII2MnII2] tetrahedron.

A graceful break-up: serendipitous self-assembly of a ferromagnetically coupled [NiII14] wheel.

The complex [NiII14(HL)(HCOO)Cl(MeOH)(HO)] describes an aesthetically pleasing wheel displaying ferromagnetic nearest neighbour exchange.