Macrocyclic Heterodinuclear CoIIMII (M = Ni, Zn) Complexes. Ferromagnetic Interaction and EPR of CoIINiII (SCo = 1/2, SNi = 1) Complex

Abstract

Abstract The dinucleating compartmental ligand (L2,3)2−, derived from the [2:1:1] cyclic condensation of 2,6-diformyl-4-methylphenol, ethylenediamine and 1,3-trimethylenediamine, has formed heterodinuclear CoIIMII complexes, [CoM(L2,3)](ClO4)2·H2O·0.5CH3CN (M = Ni (1), Zn (2)). Crystallographic studies for [CoNi(L2,3)(CH3CN)3](ClO4)2·2MeOH·0.5H2O (1′) indicate that the CoII is bound to the N2O2 site formed with ethylenediamine and has a square-pyramidal geometry with one acetonitrile molecule at the apex. The Ni is bound to the N2O2 site formed with 1,3-trimethylenediamine and has a pseudo octahedral geometry with two acetonitrile molecules at the axial sites. Complex 1 shows a ferromagnetic interaction between the CoII (S = 1/2) and NiII (S = 1) ions and a frozen DMF solution of 1 at liquid nitrogen temperature exhibits EPR signals attributable to the ST = 3/2 ground state with a zero-field splitting of D = 0.095 cm−1. The cryomagnetic property is simulated, based on isotropic model (H = −2JS1S2) and by taking into consideration the zero-field splitting, to give an exchange integral of J = +22 cm−1.