Spin State in (Porphinato)iron(III) Complex. A Spin‐Crossover Complex with Two Magnetically Distinct Sites

The results of low temperature X‐ray determination, Mössbauer and magnetic measurement of spin‐crossover (isothiocyanato)(porphinato)iron(III) hemipyridine are reported. The features in 77 K Mössbauer spectrum include two doublets, one with a quadrupole splitting (ΔE_Q) of 1.961 mm s^?1 (low‐spin site) and the other with ΔE_Q = 0.792 mm s^?1 (high‐spin site). As the temperature of the sample is increased to 300 K, the signal intensity of the high‐spin site grows to 92% at the expense of the low‐spin signal. The variable‐temperature magnetic susceptibility data also support that the tetraphenyl complex is a spin‐crossover complex.     

[(bdp)FeBr]: Structural Determination of a Polymorphic Iron Chelate with an Open‐Chain Tetrapyrrolic Ligand

Bromido‐(3,3′,4,4′,8,8′,9,9′‐octaethyl‐2,2′‐bidipyrrinato)iron(III) crystallizes in two different polymorphs, space groups and C2/c, with Z = 2 and 8, respectively, and slightly different densities. The Fe‐N and Fe‐Br bond lengths vary significantly with the polymorph indicating the presence of intermediate spin (S = 3/2) species admixed with different amounts of high spin (S = 5/2) iron(III) compounds in the triclinic resp. monoclinic form.     

Spin density distribution in transition metal complexes

The computational approaches that can be used to calculate the spin density distribution in transition metal compounds are discussed, the characteristic trends involving spin delocalization and spin polarization mechanisms are summarized, and the characteristic shapes of the spin density distributions around a transition metal atom are presented. Reference is also made to experimental methods to determine spin density distributions and to incipient work in the field of high spin molecules and single-molecule magnets.