A two-fold 3D interpenetrating cyanido-bridged network based on the octa-coordinated [Mo(CN)8]4− building block

Abstract

Complex [Ni(cyclam)]²⁺ and [Mo(CN)₈]⁴⁻ building blocks were used to construct three coordination networks differing in dimensionality and topology. The 3D {[Ni(cyclam)]₂[Mo(CN)₈]·16H₂O}_n (1) network obtained by slow diffusion of a water–ethanol mixture shows a diamond-like topology with a net of intersecting water-filled channels. The synthesis carried out in LiCl water solution leads to the 2D {Li₂[Ni(cyclam)]₃[Mo(CN)₈]₂·24H₂O}_n (2) network of honeycomb-like topology with Li⁺ cations and crystallisation water trapped in the parallel microporous channels of the structure. Additional heating of the reaction mixture results in the 2-fold interpenetrating 3D {[Ni(cyclam)]₅[Ni(CN)₄][Mo(CN)₈]₂·10H₂O}_n (3) network, containing the additional [Ni(CN)₄]²⁻ anionic building block formed in situ through partial decomposition of the starting complexes. Compound 3 consisting of two identical frameworks of diamond-like topology is a unique example of interpenetration in the family of octacyanidometallate-based assemblies. Compounds 2 and 3 undergo reversible dehydration as confirmed by dynamic vapour sorption studies and show paramagnetic behaviour arising from the presence of octahedral Ni(II) cationic complexes separated by diamagnetic [Mo(CN)₈]⁴⁻ and [Ni(CN)₄]²⁻ ions.