Photoswitchable (Cu4MoIV)-Mo-II and (Cu2MoIV)-Mo-II cyanido-bridged molecules

摘要

The self-assembly of copper(II) complexes with two Schiff base ligands: L1(O) = N-3 and L2 = N-4 and octacyanidomolybdate(IV) ions yields two discrete molecules of odd nuclearity, namely pentametallic [Cu(L1(O)) (py)](4)[Mo-IV(CN)(8)]center dot 14H(2)O (1), Cu4Mo and trimetallic [Cu(L-2)](2)[Mo-IV(CN)(8)]center dot 9H(2)O (2), Cu2Mo. Both molecular systems have been characterised structurally and magnetically, revealing a photomagnetic effect. In the case of (1) a metal-to-metal charge transfer (MMCT) mechanism is proposed. The analysis of magnetic interactions in the photogenerated state of (1) assumes the formation of the metastable cluster (Cu3CuMoV)-Cu-II-Mo-I where metal centres in Mo-V-CN-Cu-II linkages are ferromagnetically coupled with J(2) = 104(3) cm(-1). In (2) the increase in the magnetisation is due to the singlet-triplet transition on the Mo-IV centre leading to the formation of the metastable (Cu2MoHSIV)-Mo-II. The presence of the paramagnetic Mo-HS(IV) (S = 1) centre linking the Cu-II (S = 1/2) centres allows for effective ferromagnetic interaction of 3 paramagnetic centres with coupling constant J(2) = 20.2(7) cm(-1).