Million-Fold Electrical Conductivity Enhancement in Fe(2)(DEBDC) versus Mn(2)(DEBDC) (E = S, O)

[Image: see text] Reaction of FeCl(2) and H(4)DSBDC (2,5-disulfhydrylbenzene-1,4-dicarboxylic acid) leads to the formation of Fe(2)(DSBDC), an analogue of M(2)(DOBDC) (MOF-74, DOBDC(4–) = 2,5-dihydroxybenzene-1,4-dicarboxylate). The bulk electrical conductivity values of both Fe(2)(DSBDC) and Fe(2)(DOBDC) are ∼6 orders of magnitude higher than those of the Mn(2+) analogues, Mn(2)(DEBDC) (E = O, S). Because the metals are of the same formal oxidation state, the increase in conductivity is attributed to the loosely bound Fe(2+) β-spin electron. These results provide important insight for the rational design of conductive metal–organic frameworks, highlighting in particular the advantages of iron for synthesizing such materials.