Coordination polymers containing manganese(II)-azido layers connected by dipyridyl-tetrazine and 4,4′-Azobis(pyridine) linkers

摘要

Two new polynuclear manganese(II) complexes [Mn(dptz)(N_3) _2]_n (1) and [Mn(azpy)(N_3)_2] _n (2) (where dptz = dipyridyl-tetrazine and azpy = 4,4′-azobis(pyridine)) have been synthesized by self-assembly of the ligand azide, together with dptz and azpy as secondary spacers. The compounds are characterized by single-crystal X-ray diffraction analyses and variable-temperature magnetic measurements. The structural analyses reveal that in complex 1, which is the first reported Mn(II) complex with the ligand dptz, two μ_(1,3) bridging azides connect neighboring manganese ions in a zigzag manner to generate a neutral two-dimensional (2D) sheet which is further connected by the dptz ligands to form a three-dimensional (3D) framework. By contrast, complex 2 contains dimeric [Mn_2(μ_(1,1)-N _3)_2]~(2+) fragments linked to four identical motifs by means of four single μ_(1,3)-N_3 bridges, that generates a neutral 2D Mn~(II)-azide sheet which is further interconnected by azpy ligands to neighboring manganese ions forming an unprecedented 3D network. Variable-temperature (2-300 K) magnetic susceptibility measurements show the presence of predominantly antiferromagnetic coupling for both complexes that has been reproduced with a regular antiferromagnetic S = 5/2 chain (J) with interchain interactions (j) modeled with the molecular field approximation with J = -7.1 cm~(-1) and j′ = -0.8 cm~(-1) for 1 and J = -4.2 cm~(-1) and j′ = 0.1 cm~(-1) for 2.