Synthesis, structural investigations and magnetic properties of dipyridinated manganese phthalocyanine, MnPc(py)2

The MnPc(py)(2) complex was obtained in the reaction of MnPc with purified and dry pyridine under non-oxidation conditions. It crystallises in the centrosymmetric space group P2(1)/c of the monoclinic system with two molecules per unit cell. The Mn2+ cation is coordinated by four N-isoindole atoms of phthalocyaninato(2-) macrocycle and axially by two nitrogen atoms of pyridine molecules into a tetragonal bipyramid. The MnPC(py)(2) crystals are moderately stable under air, but in pyridine solution the MnPC(py)2 complex undergoes oxidation by O-2 Yieldings the binuclear manganese(III) mu-oxo complex (MnPcpy)(2)O as evidenced by the UV-Vis spectroscopy. The magnetic susceptibility measurement performed on solid sample of MnPC(py)(2) shows the Curie-Weiss behaviour in the temperature region of 300-15 K. The calculated magnetic moment mu(eff) indicates three impaired electrons (S = 3/2), thus the ground state configuration of Mn ion is (a(Ig))(2)(e(g))(2)(b(2g))(1), and the MnPc(py)(2) complex is the intermediate spin complex. Below 5.5 K (T-N) the magnetic susceptibility sharply decreases due to the cooperative intermolecular antiferromagnetic interactions. (C) 2003 Elsevier Ltd. All rights reserved.