A Host–Guest Electron Transfer Mechanism for Magnetic and Electronic Modifications in a Redox‐Active Metal–Organic Framework

Abstract Host–guest electron transfer (HGET) in molecular framework systems is a critical trigger for drastic functional changes in both host framework and guest. A reversible magnetic phase transition was achieved via HGET in a layered framework, [{Ru2(2,6‐F2PhCO2)4}2(BTDA‐TCNQ)] (1), where 2,6‐F2PhCO2− and BTDA‐TCNQ represent 2,6‐difluorobenzoate and bis[1,2,5]dithiazolotetracyanoquinodimethane, respectively. The guest‐free 1 with an antiferromagnetic ground state transformed into a paramagnet, [{Ru2(2,6‐F2PhCO2)4}2(BTDA‐TCNQ)]I3 (1‐I3), by adsorbing iodine (I2). The local charge distribution of [{Ru2II,III}+‐(BTDA‐TCNQ).−‐{Ru2II,II}] in 1 was reversibly modified to [{Ru2II,III}+‐(BTDA‐TCNQ)0‐{Ru2II,II}](I3−) in 1‐I3 through HGET. Theoretical calculations of 1‐I3 indicated a partial charge delocalization as [{Ru2}(1−δ)+‐(BTDA‐TCNQ)0‐{Ru2}δ+](I3−) with δ≈0.2, aided by weak ferromagnetic coupling. 1‐I3 exhibited a hundred‐fold enhancement in electrical conductivity compared to that of 1.