Rational Organization of Lanthanide-Based SMM Dimers into Three-Dimensional Networks

Optimization of the reaction of [Ln­(hfac)3]·2H2O and pyridine-N-oxide (PyNO), which is known to afford double-bridged dimers, leads to triple-bridged dimers of formula [(Ln­(hfac)3)2­(PyNO)3] (Ln = Gd (1), Dy (2)) from which the Dy derivative (2) behaves as a single-molecule magnet (SMM). The pseudo threefold axis symmetry of this zero-dimensional building block makes possible its extension into a tridimensional network. By changing PyNO for 4,4′-bipyridine N,N′-dioxide (4,4′BipyNO) a tridimensional compound of formula {[Ln­(hfac)3]2­(4,4′BipyNO)2]} (Ln = Eu (3), Gd (4), and Dy (5)) is then rationally obtained. This covalent three-dimensional (3D) network has a remarkably high cell volume (V = 24 419 A3) and is an arrangement of interpenetrated 3D subnetworks whose triple-bridged dimers still behave as SMMs.