The anionic oxalate-bridged bimetallic chain [Co(H2O)2Cr(ox)3]- shows slow relaxation of the magnetization, typical of the so-called single-chain magnets, when crystallized in segregated layers in a mixed salt with the supramolecular cations [C12H24O6K]+ and [(C12H24O6)(FC6H4NH3)]+. This is the first time that such phenomenon has been observed in an oxalate-bridge material. In view of the wide synthetic versatility exhibited by the oxalate ligand, it opens the door for the realization of a complete family of SCM materials whose physical properties might be tuned by the suitable replacement of M3+ ions within the chain. The information extracted from the systematic study of these compounds should provide important information concerning the main parameters that affect the slow-relaxation phenomena in this sort of 1D nanomagnets.