MAGNETIC-PROPERTIES OF HEXAAMMINERUTHENIUM(III) TRITHIOCYANATE SINGLE-CRYSTALS

The crystal structure of monoclinic (C2/c)[Ru(NH3)6][SCN], has been determined at ca. 295 K. The RuN, 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)-degrees. 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-degrees 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 pi electronic structure of the N atoms.