Abstract: We report three self-assembled iron complexes that comprised an anti-parallel open form (o-Lanti), a parallel open form (o-Lsyn), and a closed form (c-L) of diarylethene conformers. Under kinetic control, FeII2(o-Lanti)3 was isolated, which exhibited a dinuclear structure with diamagnetic properties. Under light-irradiation control, FeII2(c-L)3 was prepared and exhibited paramagnetism and spin-crossover behaviour. Under thermodynamic control and in the presence of indispensable [FeIII(Tp*)(CN)3]-, FeII2(o-Lanti)3 and FeII2(c-L)3 transformed into tetranuclear FeIII2FeII2(o-Lsyn)2, which exhibited complete spin-crossover behaviour at T1/2=353 K.
