Molecules with many spin-crossover sites could be used as multistepped molecular switches. The CNbridged molecular square [Fe II 4 (m-CN) 4 (bpy) 4 (tpa) 4 ](PF 6 ) 4 (bpy = 2,2'-bipyridine; tpa = tris(2-pyridylmethyl)amine), a Prussian blue analogue, undergoes thermally induced, two-step spin conversion. For more information, see the Communication by H. Oshio and co-workers on the following pages.

A building unit of Prussian blue was isolated as a cyanide-bridged iron cube of [Fe(II)4Fe(III)4(CN)12(tp)8] x 12 DMF x 2 Et2O x 4 H2O [tp(-) = hydrotris(pyrazolyl)borate]. A cyclic voltammogram showed quasi-reversible four-stepped redox waves, which correspond to [Fe(III)4Fe(II)4]/[Fe(III)5Fe(II)3](+), [Fe(III)5Fe(II)3](+)/[Fe(III)6Fe(II)2](2+), [Fe(III)6Fe(II)2](2+)/[Fe(III)7Fe(II)1](3+), and [Fe(III)7Fe(II)1](3+)/[Fe(III)8](4+) processes. Controlled potential absorption spectral measurements revealed two intervalence charge-transfer bands at 816 and 1000 nm, which were assigned to charge transfers from Fe(II) ions to adjacent and remote Fe(III) ions, respectively, in the cube.

Spin im Quadrat: Bei einem cyanidverbrückten molekularen Quadrat (siehe Bild) wurde ein thermisch induzierter zweistufiger Spin‐Crossover beobachtet. Moleküle mit mehr als einem Spin‐Crossover‐Zentrum eignen sich als Baueinheiten für molekulare Schalter mit mehreren Zuständen.

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A 1D compound composed of cyanide bridged iron(II,III) ions was prepared and magnetic measurements revealed it to be a single chain magnet.