Guest-effected spin-crossover in a novel three-dimensional self-penetrating coordination polymer with permanent porosity.

Porous and nonporous 3D heterobimetallic coordination polymers based on the 1,4-di(pyridin-4-yl)benzene ligand (dpb), [Fe(dpb){Ag(CN)2}{Ag2(CN)3}]·nSolv (1·nSolv; nSolv = DMF·EtOH, 2DMF·MeCN) and [Fe(dpb)2{Ag(CN)2}2] (2), have been synthesized by diffusion technique, respectively. Single-crystal X-ray analysis shows that 1·nSolv consists of a 3D self-penetrating network with in-situ-generated [Ag2(CN)3](-) species and displays one of the largest volume values of porosity (299 Å(3) per iron atom) after desolvation for the Hoffman-like porous SCO coordination polymers to date. In contrast, nonporous compound 2 is composed of two independent interpenetrated 3D nets with in-situ-generated [Ag(dpb)(CN)2](-) species. Their significant distinctions of structural architectures lead to dramatically different magnetic properties: 1·nSolv displays two-step guest-effected SCO with hysteresis, whereas 2 presents characteristic paramagnetic behavior.