Crystal structure,thermal and magnetic studies of a dinuclear Mn(II) complex with decadentate picolinate based ligand

The reaction of the decadentate ligand tpmen (H₄tpmen?=?N,N,N′N′-tetrakis(6-carboxypyridin-2-yl)methyl]ethylenediamine) with MnCl₂·4H₂O in aqueous solution gives a homodinuclear complex Mn₂(H₂O)₂(tpmen)]·16H₂O, which has been characterized by elemental analysis, thermal gravimetric and single-crystal X-ray diffraction analysis. The complex crystallizes in the orthorhombic system, space group Cmca, a?=?28.786(5) Å, b?=?11.5033(19) Å, c?=?14.437(2) Å, Z?=?8, R ₁?=?0.0432, wR ₂?=?0.0786. The tpmen ligand contains four picolinate groups, two of which bind each Mn(II) to form a dinuclear complex. The geometry around the Mn(II) is distorted octahedral with two nitrogen and two oxygen atoms from the picolinate groups and two oxygen atoms from coordinated water. The variable-temperature (2–300?K) magnetic susceptibilities shows an antiferromagnetic interaction between Mn(II) ions.