Paramagnetic susceptibilities and anisotropies of nickel(II) ions in ‘tetrahedral’ environments. Part II. Covalency and distortion in tetraethylammonium tetrachloronickelate(II), and bis-(N-isopropyl-salicylaldiminato)nickel(II)

Abstract

The magnetic susceptibilities of single crystals of tetraethylammonium tetrachloronickelate(II) and bis-(N-isopropylsalicylaldiminato)nickel(II) have been measured over the temperature range 90–300°K. The anisotropy of the chloro-complex is characterized by a reversible discontinuity at ca. 218° associated with a small thermal hysteresis. The principal susceptibilities have been fitted to a theoretical spin–triplet model. The Cl–Ni–Cl angles calculated from the magnetic data of the chloro-compound above the transition temperature agree very well with those deduced from the room-temperature X-ray structure analysis. Orbital reduction factors and spin–orbit coupling coefficients for both complexes have been determined and are discussed.