Spin crossover in the complex Fe phen 2 NCS

Another interesting application of the quadrupole splitting is the detection of spin crossover in coordination compounds. An elegant example is the comparison of the homoleptic complex [Fe(phen)3] (as its halide salts) with the mixed-ligand complex [Fe(phen)2(NCS)2]. The former is a typical low-spin compound of 

Observation of spin crossover in the complex [Fe(II)(phen)2(NCS)2] by variable-temperature Mossbauer spectroscopy. Adapted from [22]. Copyright 1967, with permission from Elsevier. 

---