Progressing in the study of magnetic interacting bimetallic systems, we present here an analysis of the magnetic behavior of the compounds Cu3[M(cdta)]2(OH2)8(NO3)2⋅7H2O(cdta is trans‐1,2‐diamine‐NNN’N’‐tetra‐acetate; M=Cu, Ni; in short, [Cu3M2]). These compounds show a novel and exotic structural arrangement. There are three different coordination positions for the metals: an octahedral‐cdta‐chelating one (Oc), which can be occupied by Cu or Ni cations, and two more, mainly hydrated, but involving oxygen atoms from the carboxylate groups of the cdta. The first of them shows square–pyramidal and the second one square‐planar topology, SP and SC, respectively, and both are always occupied by copper cations. The connectivity among these units, leading to the chains, is warranted by the cdta‐oxygen atoms, and can be described by the sequence ‐[Oc‐(SP)2‐Oc‐SC]. TheXmT‐vs‐Tproduct for the [Cu3Cu2] compound shows a significant decrease when cooling down, which shows the presence of antiferromagnetic interactions. In the case of the [Cu3Ni2] compound, it also decreases when cooling down, but reaches a minimum atT=15 K, increases reaching a maximum atT=7 K, and then goes down suddenly. These behaviors will be discussed and magnetostructural correlations will be stablished.