Crystal Structure of (CH3CH2CH2NH3)2MnCl4

Abstract

The crystal structure of (CH3CH2CH2NH3)2MnCl4 has been determined by Weissenberg single crystal diffraction techniques. The crystals are orthorhombic, space group Cmca, with a=7.29 Å, b=25.94 Å, and c=7.51 Å. Least squares refinement with anisotropic temperature factors yielded a final R value of 0.116. The outstanding feature of the structure is the existence of a two-dimensional metal—halogen framework formed by MnCl6 octahedra sharing corners. Each metal—halogen sheet is ``sandwiched'' between layers of propylammonium ions, thus effectively isolating it from adjacent sheets. This provides an exciting new class of compounds for studying two-dimensional magnetic interactions. The coordination sphere around the Mn(II) ion has approximately D4h symmetry with two Mn–Cl bond lengths of 2.475 Å and four bond lengths of 2.629 Å. Existence of N–H···Cl hydrogen bonds cause the four-fold axis of the distorted octahedra to be tipped 8.0° away from the crystallographic b axis. This produces a ``washboard'' effect when each metal—halogen sheet is viewed from the 〈 100 〉 direction and leads to nonlinear Mn–Cl–Mn bridges. A comparison with the structure of the corresponding copper(II) salts is made.