Synthesis of five isostructural tetranuclear Fe2Ln2 (Ln = Gd, Tb, Dy, Ho, Er) complexes with an 'inverse butterfly' core

A one-pot synthesis leading to in situ ligand formation enabled the preparation of five isostructural tetranuclear Fe2Ln2 coordination clusters [Fe2Ln2(μ4L)2(mpm)2(piv)2(N3)4-x(Cl)x], where H2L is 2-((pyridin-2-ylmethylene)amino)propan-1,3-diol, Hmpm is methoxy(2-pyridinyl)methanol, piv is pivalate and Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5). These show an unprecedented core structure. The coordination compounds were fully characterised by infrared spectroscopy, elemental analysis, powder X-ray diffraction and single crystal X-ray diffraction. Magnetic measurements indicate the presence of intramolecular antiferromagnetic and ferromagnetic interactions. The finding is important in developing synthetic strategies for the preparation of new molecular based magnetic materials.