Magnetic properties of hexaammineruthenium(III) trithiocyanate single crystals

Abstract

The crystal structure of monoclinic (C2/c)[Ru(NH₃)₆][SCN]₃ has been determined at ca. 295 K. The RuN₆ unit is almost of octahedral symmetry, with Ru–N bond lengths of 210.9(4) pm and N–Ru–N angles of 89.9(5)°. The single-crystal magnetic susceptibility has been obtained along the a*, b and c axes at many temperatures between 2 and 300 K. The ESR g tensor was derived from measurements taken at various angles of rotation about the a*, b and c axes, at 77 K, giving g_x= 1.468(3), g_y= 1.929(17), g_z= 2.357(4). These data are analysed in terms of an unusually complete crystal-field model in which the parameters are determined with a reliability that is rarely achieved, especially for a second-row transition-metal complex. The axes of the low-symmetry component of the crystal field, as defined by the g tensor, are aligned 12, 23 and 25° from Ru–N directions in the RuN₆ octahedron. This coincidence is probably associated with details of the positions of the hydrogen atoms, or of the SCN^– anions in the unit cell, transmitted through the π electronic structure of the N atoms.