K3REH6 - SYNTHESIS, STRUCTURE, AND MAGNET IC-PROPERTIES

K3ReH6 and K3ReD6 were synthesized by the reaction of potassium hydrid e (deuteride) with rhenium powder under a hydrogen pressure between 30 00-3500 bar at 850 K. X-ray investigations on powdered samples and ela stic neutron diffraction experiments on the deuterated compound at the triple axis spectrometer TAS 1 in the temperature range 5-600 K led t o the atomic arrangement, which corresponds to that of the cryolite wi th [ReH6](3-)-octahedra as characteristic units. Magnetic susceptibili ty measurements in the temperature range from 3.5 K and room temperatu re revealed a weak temperature independent paramagnetism. Quantum mech anical calculations confirm these facts and show in detail that the la rge value of the spin-orbit coupling parameter is essential for the ma gnetic behaviour.