Slow Magnetic Relaxation and Single-Molecule Toroidal Behaviour in a Family of Heptanuclear {Cr(III)Ln(6)(III)} (Ln=Tb, Ho, Er) Complexes

The synthesis, magnetic properties, and theoretical studies of three heterometallic {Cr(III)Ln(6) (III)} (Ln=Tb, Ho, Er) complexes, each containing a metal topology consisting of two Ln(3) triangles connected via a Cr-III linker, are reported. The {CrTb6} and {CrEr6} analogues display slow relaxation of magnetization in a 3000Oe static magnetic field. Single-crystal measurements reveal opening up of the hysteresis loop for {CrTb6} and {CrHo6} molecules at low temperatures. Abinitio calculations predict toroidal magnetic moments in the two Ln(3) triangles, which are found to couple, stabilizing a con-rotating ferrotoroidal ground state in Tb and Ho examples and extend the possibility of observing toroidal behaviour in non Dy-III complexes for the first time.