A new spin crossover heterometallic Fe(II)Ag(I) coordination polymer with the [Ag(2)(CN)(3)](-) unit: crystallographic and magnetic study.

The novel bimetallic Fe(II)Ag(I) thermal-induced spin crossover coordination polymer {Fe(II)(3,5-dimethylpyridine)(2)[Ag(I)(2)(CN)(3)][Ag(I)(CN)(2)]}(n) was synthesized by one-pot reactions between 3,5-dimethylpyridine and K[Ag(I)(CN)(2)] in the presence of Fe(II) salt (FeSO(4).(NH(4))(2)SO(4).6H(2)O). Magnetic studies demonstrate the occurrence of a spin transition. The crystal structure has been studied at 293 K and 80 K. The compound is made up of unprecedented three-dimensional networks topology of Fe(II) ions bridged by binuclear [Ag(I)(2)(CN)(3)](-) and mononuclear [Ag(I)(CN)(2)](-) units; [Ag(I)(2)(CN)(3)](-) anion is very rare. In this complex, the presence of the Ag(I) ions plays a significant role in increasing the dimensionality and cooperatively due to the triangular argentophilic interactions.