Molecules ferric wheel molecule

Electronic structure SCF spin-polarized calculations were performed with the DV method for the cluster [Fe(OC)2(02CC)]io formed by stripping the ferric wheel molecule of its peripheral H and Cl atoms (see Fig. 8) [85]. Mossbauer spectroscopy measurements have been reported [84] calculations of the hyperfine parameters were performed and compared to experiment. The magnetic moment obtained on the Fe was 4.3/ib and the charge +2.3 [85]. 

Fig. 8 - Views of the cluster (Fe(OC)2(02CC))io, representing the molecule ferric wheel a) Top view (z=0 plane), b) Side view.

In principle, all the six-membered ferric wheels [Fe6CI6(LM l7)6] (39) are isostructural and have idealized S g-molecular symmetry. However, there are fundamental differences concerning their crystal packing. For example, all the disk-like molecules of 39a are arranged in parallel and are piled in cylindrical columns, with all the iron centers superimposed. Each column is surrounded by six parallel columns, which are alternately dislocated by 1/3 c and 2/3 c against the central one (Fig. 13). 

It is evident that the majority of different structures given above provides excellent sources for further development, as illustrated exemplarily by the ferric wheels. A general feature of the metallo-coronands [Fe6Cl6(L)6] (39 Sect. 7) is the fact that the N-alkyl substituents are alternately arranged above and below the plane of the six iron ions. Interestingly, this molecular geometry offers the possibility to construct container molecules. 

One example of such systems is the circular molecule (Fe(OMe)2(02CCH2Cl)]1o denominated ferric wheel [84], of which the ground state is antiferromagnetic (S=0). A transition-metal molecule of this size constitutes a challenge for DF calculations. 

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