Spin Crossover and Field‐Induced Single‐Molecule Magnet Behaviour in Co(II) Complexes Based on Terpyridine with Tetrathiafulvalene Analogues

Two new TTF-based ligands involving terpyridine moiety (L1=4-(4′-Methyl-phenyl-2,2 : 6’,2’’-terpyridine −4-ylmethylthio)-5-(2-cyanoethylthio)-4′,5′-bis(methylthio)tetrathiafulvene and L2=4-(4′-Methyl-phenyl-2,2 −4-ylmethylthio)-5-(2-cyanoethylthio)-4′,5′-bis(propylthio)tetrathiafulvene) have been synthesized seven related mononuclear complexes were isolated as single crystals. The 2 1 (ligand metal) of formula [Co(L1)2](NO3)2 (2) [Co(L1)2](BF4)2 (3) displayed thermal spin crossover transition while the [CoCl2(L1)](DMF)2 (4), [CoBr2(L1)] ⋅ (DMF) (5), [CoCl2(L2)] 0.5(Et2O) (6) [CoBr2(L2)] (7) slow magnetic relaxation through either Raman or Raman/Direct combination processes. A relationship between structure nature processes is proposed.