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The reaction of ferric chloride and /?-diketones (HL) in alkaline methanol solution represents a good synthetic route to hexairon(1n) clusters [MFe,-(OCH,),,(L),]+ (M = Na, Li), which exhibit an unusual sixfold molecular symmetry. Single-crystal X-ray diffraction showed that the six octahedrally coordinated iron(n1) ions define a ring and are linked by twelve bridging methoxide ligands. The resulting [Fe,(OCH,),,] skeleton has the remarkable property of acting as a host for an alkali-metal ion both in the solid state and in organic solution, as demonstrated by "Na and 'Li NMR experiments. The magnetic behavior of these systems is consistent with the presence of a nonmagnetic S = 0 ground state and of antiferromagnetic exchange inter-

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A novel approach to the synthesis of pyrazole derivatives from tosylhydrazones of α,β-unsaturated carbonyl compounds possessing a β-hydrogen is proposed, exploiting microwave (MW) activation coupled with solvent free reaction conditions. The cycloaddition was studied on three ketones (trans-4-phenyl-3-buten-2-one, β-ionone and trans-chalcone). The corresponding 3,5-disubstitued-1H-pyrazoles were obtained in high yields and after short reaction times. In order to simplify and point out the green chemistry features of the method, a further improvement was achieved under the same catalytic conditions with a "one pot" synthesis of these heterocyclic compounds, starting directly from their carbonyl precursors via tosylhydrazones generated in situ. For an exhaustive study, the dielectric properties of the solid reaction mixtures were also measured, in order to obtain input data for the numerical simulation of their heating behaviour in the single mode MW cavity which was used for experimental work. In order to supply a valid methodology and tool for measuring the environmental impact, a comparative study between the synthetic route proposed and the classical synthetic route has been carried out.