{Fe(3CNpy)2[Cu(3CNpy)(mu-CN)2]2}: a one-dimensional cyanide-based spin-crossover coordination polymer

A novel one-dimensional coordination polymer made up of Fe(II), 3-cyanopyridine (3CNpy), and the singular in situ formed [Cu(I)(3CNpy)(CN)2]- anionic bridge has been synthesized. This compound undergoes a spin-crossover behavior according to its magnetic and calorimetric properties. The crystal structure of the title compound has been studied in the high- and low-spin states and correlated with the character of the spin conversion. Evidence for intense spin-state-dependent Cu....Cu interactions between the chains is also reported.