First example of photomagnetic effects in ionic pairs [Ni(bipy)3]2[Mo(CN)8] • 12H2O

Ionic triads formed by [Ni-II(bipy)(3)](2+) (bipy = 2,2'-bipyridyl) and diamagnetic [M-IV(CN)(8)](4) (M = Mo and W) were prepared and structurally characterized. The two compounds are isostructural and their structure consists of a three-dimensional hydrogen-bonded framework where cation-anion interactions occur through short contacts M-CN center dot center dot center dot H-C(bipy). Before irradiation, the Mo analogue behaves as paramagnet with small intermolecular interactions between the [Ni-II( bipy) 3] 2+ cations. Upon irradiation with visible light, it exhibits a reversible photomagnetic effect, which is interpreted in terms of the formation of paramagnetic [Mo-V(CN)(8)](3) and [Ni-II(bipy)(2)(bipy(center dot))](+) due to the outer-sphere electron transfer. (c) 2008 Elsevier B. V. All rights reserved.