Experimental and Theoretical Identification of the Origin of Magnetic Anisotropy in Intermediate Spin Iron(III) Complexes

The complexes [(FeLX)-X-N2S2] [in which L-N2S2 = 2,2'-(2,2'-bipryridine-6,6'-diyl)bis(1,1'-diphenylethanethiolate) and X = Cl, Br and I], characterized crystallographically earlier and here (Fe(L)Br), reveal a square pyramidal coordinated Fe-III ion. Unusually, all three complexes have intermediate spin ground states. Susceptibility measurements, powder cw X- and Q-band EPR spectra, and zero-field powder Mossbauer spectra show that all complexes display distinct magnetic anisotropy, which has been rationalized by DFT calculations. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3204]