Metamagnetism of the First Cyano-Bridged Two-Dimensional Brick-Wall-like 4f−3d Array

[Gd(DMF)2(H2O)3Cr(CN)6]·H2O is the first lanthanide−transition metal array with a flat two-dimensional brick-wall-like molecular structure. The antiferromagnetic coupling between the adjacent Gd−Cr ions leads to intralayer ferrimagnetic correlation due to the noncancellation of spins. The long-range magnetic ordering (TN = 3.5 K) was observed for the first time in low-dimensional cyano-bridged 4f−3d coordination polymers. Metamagnetic behavior was observed at 1.8 K arising from antiferromagnetic coupling between the ferrimagnetic layers.