Two cyano-bridged heterotrinuclear complexes built from [(Tp)Fe(CN)(3)](-) (Tp = hydrotris(pyrazolyl)borate): synthesis, crystal structures and magnetic properties
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abstract
Using an anionic precursor [(Tp)FeIII(CN)3] - (1) as a building block, two cyano-bridged centrosymmetric heterotrinuclear complexes, [(Tp)2Fe2III(CN)6MnII(C2H5OH)4]2C2H5OH (2) and [(Tp)2Fe2III(CN)6Ni(en)2] (3) (en = ethylenediamine), have been synthesized and structurally characterized. In each complex, [TpFe(CN)3] - acts as a monodentate ligand toward a central [Mn(C 2H5OH)4]2+ or [Ni(en) 2]2+ core through one of its three cyanide groups, the other two cyanides remaining terminal. The intramolecular Fe-Mn and Fe-Ni distances are 5.2354(4) and 5.0669(11) , respectively. The magnetic properties of complexes 2 and 3 have been investigated in the temperature range of 2.0-300 K. A weak antiferromagnetic interaction between the Mn(II) and Fe(III) ions has been found in complex 2. The magnetic data of 2 can be fitted with the isotropic Hamiltonian:=- 2J(12+23)- 2J13 where J and J are the intramolecular exchange coupling parameters between adjacent and peripheral spin carriers, respectively. This leads to values of J = -1.37 cm-1 and g = 2.05. The same fitting method is applied to complex 3 to give values of J = 1.2 cm-1 and g = 2.25, showing that there is a ferromagnetic interaction between the Fe(III) and Ni(II) ions. 2004 Elsevier B.V. All rights reserved.
