Auxiliary ligand-induced structural diversities of octacyanometalate-based heterobimetallic coordination polymers towards diverse magnetic properties.

Abstract

Three octacyanometalate-based bimetallic coordination polymers (CPs), {[μ4-MV(CN)8][Co(DMF)4]2(ClO4)}n (M = W CP-1, Mo CP-2) and {[μ4-WIV(CN)8]Co2(azpy)4}n CP-3, were synthesized in the absence (for CPs 1 and 2) or presence (for CP-3) of auxiliary ligand 4,4'-azopyridine (azpy), respectively. CPs 1 and 2 exhibit the same three-dimensional (3D) polymeric cation frameworks with [ClO4]- as the counterions, while CP-3 displays a porous 3D framework in an unusual 2-nodal (4,6)-connected 4,6T155 topology with point symbol as {42·64}{46·64·7·84}2. Notably is that octacyanometalate [WV(CN)8]3- has been reduced into [WIV(CN)8]4- during the synthetic process of CP-3. The magnetic investigations indicate that CP-1 exhibits the typical ferromagnetic property due to the ferromagnetic coupling between W(v) and Co(ii) spin centers, while CP-3 displays the weak ferromagnetic interaction at low temperature, which is consistent with the valence change of W center in CP-3.