Octacyanidotungstate(IV) Coordination Chains Demonstrate a Light-Induced Excited Spin State Trapping Behavior and Magnetic Exchange Photoswitching.

A huge increase in the magnetization of two coordination chains based on tetravalent octacyanidometalates (WIV and MoIV ) is observed on irradiation with 436 nm light, while no such behavior is observed for the NbIV analogue. A photomagnetic response based solely on [WIV (CN)8 ]4- is demonstrated for the first time. The observed behavior is attributed to the light-induced excited spin state trapping (LIESST) effect at the octacyanidometalate, and to the resulting magnetic exchange ON/OFF photoswitching between the MnII center and the photoinduced high-spin (S=1) WIV or MoIV centers.