Molecular ferromagnetics

Still higher nuclearities, up to 12 in [Mni20i2-(RC00)i6(H20)4] (R = Me, Ph), have been reported.The cores of these two compounds, which are of interest as potential building blocks in the preparation of molecular ferromagnets, consist of a central Mn4 (/Li-0)4 cubane linked by O-bridges to eight Mn atoms. 

Buchachenko, A.L. (1990) Organic and molecular ferromagnetics advances and problems, Russ. Chem. Rev., 59,307-319. 

Fig. 2 A conceptual sketch for constructing molecular ferromagnets. Arrows and ellipsoids represent the electron spins and molecular boundaries, respectively. Bold arrows show where careful molecular design is necessary.

The first chemical transformations carried out with Cjq were reductions. After the pronounced electrophilicity of the fullerenes was recognized, electron transfer reactions with electropositive metals, organometallic compounds, strong organic donor molecules as well as electrochemical and photochemical reductions have been used to prepare fulleride salts respectively fulleride anions. Functionalized fulleride anions and salts have been mostly prepared by reactions with carbanions or by removing the proton from hydrofullerenes. Some of these systems, either functionalized or derived from pristine Cjq, exhibit extraordinary solid-state properties such as superconductivity and molecular ferromagnetism. Fullerides are promising candidates for nonlinear optical materials and may be used for enhanced photoluminescence material. 

Chavan, S. A., J. V. Yakhmi, andl. K. Gopalakrishnan, Molecular ferromagnets—a review. 

These complexes, as well as their solvates contained in an alcohol, yield complex compounds of type 447 this group of compounds plays an important role amongst molecular ferromagnetics [790]. 

We start with a review on the basic theory and experiments followed by an analysis of typical experimental data. Considerable attention will then be devoted to the emerging field of molecular ferromagnets and to applications. 

Hatscher, S.T. and Urland, W. (2003) Unexpected appearance of molecular ferromagnetism in the ordinary acetate [ Gd(0Ac)3(H20)2 2]4H20. Angewantite Chemie International Edition, 42, 2862-2864. 

TTF][TCNQ] was the first organic conductor [279] and the salt [FeCp 2][TCNE] was one of the very first molecular ferromagnets [277, 280]. 

This explains why a significant part of this work will be devoted to the design of fer-romagnetically coupled systems and of molecular ferromagnets, which is one of the main challenges in the field of the molecular materials. 

In this section, we purpose to introduce the concept of regularity and irregularity in the spin state structure. This concept already led to the synthesis of polymetallic systems in which the ground state has a very high spin multiplicity. It might be a key for the design of molecular ferromagnets, as we shall see it in Sect. 12. 

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