Syntheses, structures and magnetic properties of the tricyanoethenolate adducts of quadridentate Schiff base manganese(III) complexes

Abstract

Manganese(III) complexes [Mn(L 1)(NCO)] and [Mn(L 2)(NCO)] (H 2L 1 = N, N′-ethylenebis(3-hydroxy-4-naphthylideneiminate), H 2L 2 = N, N′-(1,1,2,2-tetramethylethylene)bis(3-hydroxy-4-naphthylideneiminate)) react with tetracyanoethylene in a mixed solution of dichloromethane and acetonitrile to give the tricyanoethenolate adducts [Mn(L 1)(TCEA)(H 2O)] ( 1) and [Mn(L 2)(TCEA)] ( 2) (TCEA = tricyanoethenolate, [(NC) 2C=C(CN)O −]), respectively. Compound 1 crystallizes in the triclinic space group P 1 with a = 10.612(5), b = 13.369(5), c = 9.981(6) A ̊ , α = 108.89(4), β = 110.70(4), γ = 77.22(4)° . The Mn(III) assumes an elongated square bipyramidal geometry, in which two apical sites are occupied by an oxygen atom of a water molecule with MnO(3) = 2.305(4) Å and by a nitrogen atom of TCEA with MnN(3) = 2.390(4) Å. The water oxygen is hydrogen bonded to a nitrogen atom of TCEA of the adjacent molecular unit with O(3)N(3) ∗ = 3.081(6) Å forming a one-dimensional chain structure of head-to-tail fashion. Compound 2 crystallizes in the monoclinic space group P2 1/c with a = 14.107(6), b = 12.750, c = 16.481(5) A ̊ , β = 103.64(3)° . Compound 2 has a binuclear structure of out-of-plane fashion, where the dimensions of the Mn 2O 2 core are MnMn ∗ = 3.475(2) Å and MO(1) ∗ = 2.627(3) Å. The Mn(III) assumes a distorted square bipyramidal geometry, in which two apical sites are occupied by the phenoxy oxygen atom of L 2 and an oxygen atom of the TCEA anion with 2.163(3) Å. The magnetic susceptibility measurements in the range 4.4–300 K showed that a weak intermolecular antiferromagnetic interaction or/and zero field splitting is operating for 1, while a intradimer ferromagnetic interaction is operating for 2.