Magnetic Correlation Engineering in Spin‐Sandwiched Layered Magnetic Frameworks

The insertion of “sandwiched spins” between magnetic layers could efficiently affect the interlayer magnetic correlations, but doing so increases the complexity in the interlayer spin alignment because of competition between the inserted spin‐layer interaction JNNI and the interlayer through‐space interaction JNNNI if the magnitude of JNNI is of the same order as JNNNI with reciprocal signs of the respective interactions. Herein, systematic tuning of the magnetic phase variations by JNNI and JNNNI in two kinds of metal‐variable isostructural series of supramolecular pillared layer magnets [MCp*2][{Ru2II,II(2,3,5,6‐F4CO2)4}2(TCNQ)]⋅2 DCE (M=Co, Fe, Cr; 2,3,5,6‐F4PhCO2−=2,3,5,6‐tetrafluorobenzoate; TCNQ=7,7,8,8‐tetracyano‐p‐quinodimethane; DCE=1,2‐dichloroethane) and their DCE‐free series, in which [MCp*2]+ (Cp*=η5‐C5Me5) species with S=0, 1/2, and 3/2 for M=Co, Fe, Cr, respectively, are sandwiched between ferrimagnetic layers of [{Ru2}2(TCNQ)]−, is demonstrated. The results showed that the flexible magnetic natures of these magnets are changeable in dependence on JNNI and JNNNI, as well as on interlayer inserted spins M. Magnetic sandwiches: What happens in a spin‐sandwiched layered magnet when the sandwiched spin is altered? Herein, this question was answered for two series of isostructural compounds by changing [MCp*2]+ spins sandwiched between ferrimagnetic layers of [{Ru2}2(TCNQ)]−. The magnetic phase can be described as a competition between the interlayer magnetic interaction and the layer⋅⋅⋅[MCp*2]+ interaction, which were tuned by solvation/desolvation and by changing M among Co, Fe, and Cr, respectively. Cp*=pentamethylcyclopentadienyl, TCNQ=7,7,8,8‐tetracyano‐p‐quinodimethane