Crystallographic and dielectric studies of tetrahedral {NH4@Fe4} crystallized with halomethane molecules†
Abstract
Crystal structures of a tetrahedral Fe4 cluster (NH4@Fe4 ≡ 1) were investigated using a set of crystals prepared by changing the halomethane (CCl4, CHCl3, CHBr3, CH2Cl2, CH2Br2) used as the crystalline solvent. X-ray diffraction studies using single crystals clarified the structural distortion of 1 from the regular tetrahedron in pristine 1·15.88H2O. We revealed that central ammonium stabilizes the distorted structure by forming an intramolecular hydrogen bond with a ligand. By impedance measurements of the crystals, Debye-type dipole relaxations of the guest molecule were observed around 100 K.