Single-molecule magnetism in cyclopentadienyl-dysprosium chlorides.

[Cp(2)Dy(thf)(μ-Cl)](2) (2) was synthesized from [Cp(2)Dy(μ-Cl)](n), which crystalizes as two polymorphs, with n = 2 (1a) or ∞ (1b). All three compounds show slow relaxation of magnetization, and in 2 the quantum tunnelling was found to be exchange-biased.