Photomagnetic Response in Highly Conductive Iron(II) Spin‐Crossover Complexes with TCNQ Radicals

Co‐crystallization of a cationic Fe II complex with a partially charged TCNQ . δ − (7,7′,8,8′‐tetracyanoquinodimethane) radical anion has afforded molecular materials that behave as narrow band‐gap semiconductors, [Fe(tpma)(xbim)](X)(TCNQ) 1.5 ⋅DMF (X=ClO 4 − or BF 4 − ; tpma=tris(2‐pyridylmethyl)amine, xbim=1,1′‐(α,α′‐ o ‐xylyl)‐2,2′‐bisimidazole). Remarkably, these complexes also exhibit temperature‐and light‐driven spin crossover at the Fe II center, and are thus the first structurally defined magnetically bistable semiconductors assembled with the TCNQ . δ − radical anion. Transport measurements reveal the conductivity of 0.2 S cm −1 at 300 K, with the low activation energy of 0.11 eV.