Magnetic Exchange through the Dianionic Hexaazatrinaphthylene (HATNA) Ligand in {HATNA(Fe II Cl 2 ) 3 } 2− Containing Fe II ( S =2) Triangles

Herein, a new method for the preparation of anionic hexaazatrinaphthylene (HATNA) coordination complexes was developed. The reduced HATNA coordinated three Fe II Cl 2 units for the formation of (CV + ) 2 {HATNA(Fe II Cl 2 ) 3 } 2−  ⋅ 3.5 C 6 H 4 Cl 2 ( 1 ) (CV + is a cationic form of crystal violet). The Fe II atoms had a high S =2 spin state and were arranged in nearly equilateral triangles at a distance of approximately 7 Å. The χ M T value of 1 was 9.70 emu⋅K/mol at 300 K, exceeding the calculated spin‐only value of three independent high‐spin Fe II centers ( S =2) (9.00 emu⋅K/mol). A strong antiferromagnetic exchange was observed between Fe II atoms through the diamagnetic HATNA units since Weiss temperature is −98 K. Magnetic behavior of 1 was modelled by PHI package obtaining the exchange interaction constant J =−4.6 cm −1 and zero‐field splitting parameter D =5.6 cm −1 at g =2.23. Arrangement of magnetic centers in the equilateral triangles supposes that some degree of spin frustration exists in 1 . Crystal structures of two phases of pristine HATNA molecule are also reported.