Field induced single ion magnet behavior in Co^II complexes in a distorted square pyramidal geometry

We report three Co-II-based complexes with the general formula [CoII(L)(X)2] by changing the halide/pseudo-halide ions [X = NCSe (1(SeCN)); Cl (2(Cl)) and Br (3(Br))]. The obtained tau(5) and CShM values confirm a distorted square pyramidal geometry around the Co-II ion in all these complexes. In these three complexes, the central Co-II ion is situated above the basal plane of the square pyramidal geometry. The extent of distortion from the ideal SPY-5 geometry differs upon changing the coordinating halide/pseudo-halide ion in these complexes. This essentially results in the alteration of the anisotropic parameter D and hence impacts the magnetic properties in these complexes. This phenomenon has been corroborated with the aid of theoretical investigations. All these complexes display field-induced SIM behaviour with magnetic relaxation occurring through a combination of processes depending on the applied dc magnetic field values and dilution.