Synthesis, Crystal Structure, Magnetism, Band Structure and Density of States of [CHN]ClCoCl.

The crystal structure of [1-(2-aminoethyl) piperazinium] choride trachloridocobaltate (II): [CHN] ClCoCl has been synthesized and analyzed by X-ray diffraction. Magnetization was used to investigate the magnetic properties. The salt crystallizes at room temperature in the monoclinic system with space group P2, the unit cell dimensions are: a=7.2113 Å, b=12.4844 Å, c=8.0554 Å, β=97.274 with Z = 2. The crystal structure of this salt was solved by Patterson methods and refined by full-matrix least squares on F to final values of R=0.0361 and wR=0.0701. The structure consists of monomeric triprotonated [1-(2-aminoethyl) piperazinium] cations, monomeric $\mathrm{CoCl}_{4}^{2-}$ and Cl anions. These entities are interconnected by means of hydrogen bonding contacts forming a three-dimensional network. The magnetic measurements experimentally show a deviation from the Curie-Weiss law at low temperatures, which reveals the occurrence of weak ferromagnetism at low temperature. The measurements of isothermal magnetics at low temperature show a weak hysteresis, which was confirmed by the small coercive field found at low temperature. In addition, self-consistent ab initio calculations, based on FLAPW method (Wien2k code), are performed to investigate magnetic, electronic properties and crystal structure, of [1-(2-aminoethyl) piperazinium] choride trachloridocobaltate(II). Spins polarized within the framework of the Coherent Potential Approximation (CPA) are considered. [ABSTRACT FROM AUTHOR]