Fully interlocked three-dimensional molecular scaffolding: Synthesis, X-ray structure, magnetic and nitrogen sorption study

The reaction of M(NO3)2·6H2O (M = Co or Ni), N,N-diethyl-ethylenediamine (deen) and sodium dicyanamide (dca) afforded the complex {[M(deen)(μ1,5-dca)2]}n (where for 1, M = Co and for 2, M = Ni). The complexes have been characterized structurally and magnetically. X-ray analysis reveals that the isomorphous complexes 1 and 2 feature similar infinite three-dimensional scaffolding-like structure to generate the fascinating molecular assembly. All the {N(CN)2}− ligands present in the complexes are connected to the symmetry related metal centers in an end-to-end fashion through bent {N(CN)2}− ligands. The zigzag linkage propagates parallel to three crystallographic axes to form a fully interlocked 3D structure. The variable temperature (4–300 K) magnetic susceptibility measurements showed that the magnetic interaction between the metal centers in the complex 1 is dominantly antiferromagnetic. However, the compound 2 is a simple paramagnet. The N2 sorption analysis reveals that the complexes 1 and 2 are porous.