Structural properties and vibrational spectra of the ethylene-diammonium family of perovskite layer-type crystals: [NH 3CH 2CH 2NH 3] [ MCl 4], M = Ni, Pd, Cu, Cd, Mn

A new compound, (NH ₃CH ₂CH ₂NH ₃) NiCl ₄, has been prepared and investigated. Magnetism and powder X-ray diffraction photographs in combination with electronic and vibrational spectra indicate a weakly paramagnetic structure containing two-dimensional perovskite-type layers of tetragonally distorted cornersharing NiCl ₆ octahedra. The unit cell dimensions are: a = 8.441 ± 0.001, b = 6.995 ± 0.001, c = 6.943 ± 0.001 Å, β = 92.925 ± 0.002°, in space group {P2 ₁}/{c} (C ⁵_2h), Z =2 . It is shown that this compound and the corresponding Pd compound belong to an isostructural family of crystals: (NH ₃CH ₂CH ₂NH ₃) MCl ₄, M = Ni, Pd, Cu, Cd, Mn. The vibrational spectra of these compounds are discussed in relation to the structure.