Controlling magnetic exchange coupling via coligands in three cyanide-bridged heterobimetallic complexes

Three one-dimensional (1D) cyanide-bridged heterobimetallic chains {[FeIII(Tp)(CN)3]2CoII(mep)2}·2CH3OH (1; Tp = hydrotris(pyrazolyl)borate, mep = 4‑[(1E)‑2‑(4‑Methylphenyl)ethenyl]pyridine), {[FeIII(Tp)(CN)3]2CoII(eep)2}·2CH3OH (2; eep = 4‑[(1E)‑2‑(4‑Ethylphenyl)ethenyl]pyridine) and {[FeIII(Tp)(CN)3]4CoII2(nep)4}·3H2O·CH3OH (3; nep = 4‑[(1E)‑2‑(2‑Naphthalenyl)ethenyl]pyridine) have been synthesized via self-assembly of the same [FeIII(Tp)(CN)3]− unit and CoII ion in the presence of different N-substituted pyridine ligands. Magnetic measurements reveal that complex 1 exhibits ferromagnetic interactions and a long-range magnetic ordering below 3.5 K. Complex 2 shows antiferromagnetic long-range ordering below 3.3 K, while complex 3 shows a typical ferrimagnetic coupling at low temperatures. These results highlight the significant influence of the coligands on their magnetic properties.