Study of a novel hepta-coordinated FeIII bimetallic complex with an unusual 1,2,4,5-tetrazine-ring opening

Abstract

Reaction of Fe(NO3)3 with 3,6-di(pyrimidin-2-yl)-1,2,4,5-tetrazine (BPymTz) in acetonitrile gives a hepta-coordinated FeIII complex (1) with the bridging unit 1,2-diiminohydrazido (1,2-dih2−: −HNC(R) NNC(R)NH−) generated in situ from the tetrazine ring-opening of BPymTz. DFT calculations, X-ray diffraction studies and SQUID magnetometry measurements were successfully performed on 1. The crystallography measurement confirms the ring-opening and the substituent’s contribution to the rare pentagonal bipyramidal coordination geometry of the metal ions. Magnetic susceptibility measurements on 1 reveal an S=0 ground state, arising from the antiferromagnetic interaction between the two FeIII centers (J=−3.02cm−1) within the molecule.