Five new pseudohalide bridged Mn(II) complexes of pyrimidine derived Schiff base ligands: Synthesis, crystal structures and magnetic properties

Four new azide bridged dinuclear Mn(II) complexes [Mn(L1)(μ1,1-N3)(N3)]2 (1), [Mn(L2)(μ1,1-N3)(N3)]2 (3), [Mn(L3)(μ1,1-N3)(N3)]2[(N3)Mn(L3)(μ1,1-N3)(N3)]2 (4) and [Mn(L4)(μ1,1-N3)(N3)]2[Mn(L4)(μ1,1-N3)(N3)]2 (5) and one new dicynamide bridged binuclear Mn(II) complex {[Mn2(L1)2(dca)2(H2O)2(μ1,5-dca)](ClO4)} (2) have been synthesized using the pyrimidine derived primary Schiff base ligands Ln (n = 1–4), with azide and dicynamide as bridging ligands. All the five complexes were characterized by elemental analyses, IR spectroscopy and single crystal X-ray crystallography, together with magnetic measurements of 1–4. The tridentate Schiff base ligands are the [1 + 1] condensation products of 2-hydrazino-4,6-dimethyl pyrimidine with 2-acetyl pyridine, pyridine-2-carbaldehyde, 2-benzoyl pyridine and di(2-pyridyl) ketone for Ln (n = 1–4), respectively. All the complexes except 2 contain Mn(II)-azido links in which the Mn(II) centres are bridged by a di-μ1,1-azido (double EO) group. The double EO bridging fragments in the complexes are similar with bridging angles (Mn–N–Mn) ranging from 102.59° to 104.81°. Magnetic property studies reveal that in 1, 3 and 4 intramolecular ferromagnetic interactions are mediated through the EO azido bridges with J parameters in the range 4.3–5.12 cm−1, while a weak antiferromagnetic interaction prevails in 2 (J = −0.12 cm−1) via μ1,5-dicynamide bridges. In addition, complexes 1, 3 and 4 show weak intermolecular antiferromagnetic interactions (J = −0.025 to −0.027 cm−1).

The synthesis, crystal structures and magnetic behaviour of azide bridged binuclear Mn(II) complexes and one dicynamide bridged binuclear Mn(II) complex of pyrimidine derived Schiff base ligands Ln (n = 1–4) are reported. The intramolecular ferromagnetic interactions are mediated through the EO azido bridges with J parameters in the range 4.3–5.12 cm−1 in [Mn(L1)(μ1,1-N3)(N3)]2, [Mn(L2)(μ1,1-N3)(N3)]2 and [Mn(L3)(μ1,1-N3)(N3)]2[(N3)Mn(L3)(μ1,1-N3)(N3)]2, while a weak antiferromagnetic interaction (J = −0.12 cm−1) via μ1,5-dicynamide bridges prevails in {[Mn2(L1)2(dca)2(H2O)2(μ1,5-dca)](ClO4)}.Figure optionsDownload as PowerPoint slide