Structural Conversion and Magnetic Studies of Low-Dimensional LnIII/MoV/IV(CN)8 (Ln = Gd-Lu) Systems: From Helical Chain to Trinuclear Cluster

The slow diffusion reaction of octacyanometallate [Mo-v(CN)(8)](3-), lanthanide ions (Gd-Lu), and 1,10-phenanthroline (phen) in CH3CN/H2O has yielded eight isostructural one-dimensional chains, [Ln(III)(phen)(2)(H2O)Mov(CN)(8)](2)-[(n-C4H9)(4)N](NO3)center dot 2CH(3)CN center dot 4H(2)O (Ln = Gd(1), Tb(2), Dy(3), Ho(4), Er(5), Tm(6), Yb(7), Lu(8)), in which [Ln(III)(phen)(2)(H2O)](3+) and [Mo-v(CN)(8)](3-) units are linked alternatively through cyanide groups, generating left- and right-handed helices. Interestingly, 1-8 undergo a resolvation-recrystallization process upon prolonging the diffusion-reaction time, together with the valence change from V to IV of Mo center and structural dimensionalities switching from helical chains to trinuclear clusters, (Hphen)(2.5)[Ln(0.5)(III)(phen) (H2O)] [Mo-IV(CN)(8)]center dot 1.5 CH3CN (Ln = Gd (9), Tb(10), Dy(11), Ho(12), Er(13), Tm(14), Yb(15), Lu(16)). Magnetic studies of 1-16 revealed the typical effects induced by single-ion magnetic anisotropy and/or the population of low-lying excited states, and 11 and 13 showed extraordinary field-induced slow magnetic relaxations.