Quantum Monte Carlo Simulations and High-Field Magnetization Studies of Antiferromagnetic Interactions in a Giant Hetero-Spin Ring.

Chromium lanthanide heterometallic wheel complexes {Cr8 Ln8 } (Ln=Gd, Dy and Y) with alternating metal centres are presented. Quantum Monte Carlo simulations reveal antiferromagnetic exchange-coupling constants with an average of 2.1 K within the {Cr8 Gd8 } wheel, which leads to a large ground spin state (ST =16) that is confirmed by magnetization studies up to 20 Tesla. The {Cr8 Dy8 } wheel is a single-molecule magnet.