Enhancing SIM behaviour in a mononuclear tetrahedral [Co(,′-2-iminopyrrolyl)] complex

A new homoleptic Co( ii ) complex bearing two highly sterically congested 2-formiminopyrrolyl N , N ′-chelating ligands is reported, displaying slow relaxation of the magnetisation at zero static (DC) field. This compound shows a large value for the zero-field splitting (ZFS) parameter D of −42.6(4) cm −1 leading to a spin-reversal energy barrier U eff of 85 cm −1 . Co( ii )-N 4 complex displays slow magnetisation at zero static field, exhibiting a high spin-reversal energy barrier U eff = 85 cm −1 .