Experimental and theoretical magnetostructural studies on discrete heterometallic cyanide-bridged dinuclear FeIIIMnII and tetranuclear Fe2III Cu2II complexes bearing tripodal pyrazolyl borate and tetradentate phenolate-based ligands

Two new complexes [Fe-III(Tp)(CN)(2)(mu-CN)(MnCl)-Cl-II(HL1)]center dot 3DMF (1) and {[Fe-III(Tp)(CN)(mu(2)-NC)2Cu(II)(HL2)] (ClO4)}(2)center dot 6DMF (2) (HL1 = 2-((((1-methylbenzimidazol-2-yl)methyl)( pyridin-2-ylmethyl)amino)methyl) phenol and HL2 = 2-((( pyridin-2-ylmethyl)(quinolin-2-ylmethyl)-amino)methyl)phenol) have been synthesized and characterized by elemental analysis and IR and UV/vis spectroscopy. Structural analysis revealed that 1 is a discrete dinuclear coordination complex and 2 is a discrete tetranuclear coordination complex. In complex 1, each Mn-II is in a distorted octahedral MN4OCl environment where coordination is satisfied by three nitrogen atoms and one oxygen atom of the ligand, and a chloride group and one nitrogen atom from cyanide. In complex 2, each Cu is in a distorted octahedral MN5O environment where coordination is satisfied by three nitrogen atoms and one oxygen atom of the ligand, and two nitrogen atoms from two cyanides. Direct current (dc) variable-temperature magnetic susceptibility measurements on polycrystalline samples of 1 and 2 were carried out in the temperature range of 1.8-300 K. Investigation of the magnetic properties reveals the occurrence of weak antiferromagnetic coupling between the low-spin Fe-III (S = 1/2) ions and high-spin Mn-II (S = 5/2) ions in 1, while 2 exhibits ferro- and antiferromagnetic coupling between the metal ions in the tetranuclear Cu(2)(II)Fe2(III) unit. DFT calculations show ferromagnetic coupling in both complexes, although this appears to be weak in the case of complex 1. In addition, magnetostructural correlations reveal the magnetic behavior against Mn-N-C and Fe-C-N angles in 1 and Cu-N-C and Fe-C-N angles in 2.

Automated summary

Two new coordination complexes have been synthesized and characterized. Complex 1 is a dinuclear coordination complex and complex 2 is a tetranuclear coordination complex. Magnetic studies reveal weak antiferromagnetic coupling between low-spin Fe-III and high-spin Mn-II ions in complex 1, while complex 2 exhibits both ferro- and antiferromagnetic coupling between metal ions in the tetranuclear Cu2(II)Fe2(III) unit.