Synthesis, structural and magnetic study of two new alternating 1D azido-bridged cobalt(II) complexes

Two new one-dimensional azido-bridged Co(II) compounds with formula [Co2(μ1,1-N3)2(μ1,3-N3)2(4-Etpy)4]n (1) and [Co3(μ1,1-N3)4(μ1,3-N3)2(3-pic)6]n (2) (4-Etpy = 4-ethylpyridine, 3-pic = 3-picoline) have been structurally and magnetically characterized. Compound 1 crystallizes in the monoclinic system with space group Cc and compound 2 in the triclinic system with space group P1¯. In both complexes the cobalt centers are octahedrally coordinated by two pyridine derivative ligands in trans-conformation and four azido groups. In 1, the azido groups act in the alternating di-EO/di-EE bridging mode to form the 1D system oriented along the a-axis of monoclinic unit cell, whereas in 2, the 1D system along the triclinic c-axis is built by the di-EO/di-EO/di-EE topology of azido bridges, the first example for Co(II) ions.The magnetic properties of 1 and 2 are reported. Both complexes obey the Curie–Weiss law at high temperatures with negative Weiss constants of θ = −65.9 and −63.6 K for 1 and 2, respectively. At low temperatures 1 and 2 are weak ferromagnets due to spin canting.

Two new one-dimensional azido-bridged Co(II) compounds with formula [Co2(μ1,1-N3)2(μ1,3-N3)2(4-Etpy)4]n (1) and [Co3(μ1,1-N3)4(μ1,3-N3)2(3-pic)6]n (2) (4-Etpy = 4-ethylpyridine, 3-pic = 3-picoline) have been structurally and magnetically characterized.Figure optionsDownload as PowerPoint slideHighlights
► Two new alternating Co(II) azide chains are reported.
► The di-EO/di-EO/di-EE azide bridging topology of 2 is first time observed for Co2+ cation.
► Both complexes show bulk antiferromagnetic coupling in the high temperature region.