The crystal engineering of octacyanidomolybdate(IV) ions and copper(II) complexes with two types of chelating ligands: multidentate blocking, tren = (tris(2 aminoethyl)amine, and bidentate capable of forming unusual organic bridges, tn...

The design and synthesis of high-dimensional materials based on secondary building blocks (SBUs) play a pivotal role in the further development of functional molecular materials. Herein, the self-assembly of Cu­(II) ions, pyrazole (Hpz), and octacyanidometallate­(IV) anions in the presence of water produced two new isostructural three-dimensional systems {[Cu3(μ3-OH)­(μ-pz)3(H2O)3]2[M­(CN)8]}·nH2O (M = W, 1, and Mo, 2). 1 and 2 consist of trinuclear triangle copper­(II) (TTC) SBUs and octacyanidometallates­(IV). At room temperature, both assemblies display strong antiferromagnetic interactions within the TTC entities with an average CuII···CuII isotropic magnetic coupling constant of about −145 cm–1. Moreover, a detailed analysis of magnetic data revealed the presence of spin frustration with antisymmetric magnetic exchange-coupling constants of around +32 and +46 cm–1 for 1 and 2, respectively. Finally, quantum chemical calculations explained their magnetic and optical properties.