Antiferromagnetic coupling units

The second salt presents a structure where the anions occupy the tunnels formed by BEDT-TTF dimers. BEDT-TTF bears the unit positive charge. This salt behaves like a semiconductor with a very low room-temperature electric conductivity. The unpaired electrons on the organic cation-radicals are strongly antiferromagnetic coupled, giving rise to a diamagnetic behavior of the second salt, because the nitroprusside anion is also diamagnetic. 

To what extent are the binuclear units in the purple acid phosphatases analogous to those found in hemerythrin and ribonucleotide reductase There are similarities and differences. The oxidized form is purple and EPR silent with strong antiferromagnetic coupling between the two Fe(III) centers the reduced form is pink and EPR active (gav = 1.7-1.8) with weak antiferromagnetic coupling between the Fe(III)-Fe(II) centers (3,72,73). 

The synthesis, structure, and magnetic properties of an octairon(III) citrate complex, [Feg(/r3-0)2(/i-OH)2(citrate)6(02CMe)2(imidazole)2], have been described. This complex consists of two equivalent tetranuclear units linked by two citrates the Fe ions are antiferromagnetically coupled in a four S = 5/2 spin system. [Feg0(citrate)8(H20)3] has a three-layer citrate-bridged structure. 

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