Single Crystal ESR Studies of n-Tetrabutylammonium+Nickel(o-Benzene-Diselenolate)2− and Related Transition Metal Complexes

Abstract

Previously reported temperature dependent studies of the ESR spectral envelopes of polycrystalline samples of n-tetrabutylammonium salts of nickel(o-benzenediselenolate(bds))2 and nickel(o-benzenedithiolate(bdt)2 reveal that the g-tensors for the bds and bdt salts are axial and pseudo-axial, respectively1–5. However, there was concern that the g-tensor for the bds might actually be pseudo-axial because of the poorer resolution as a result of the increased ESR spectral linewidth in the selenium salt due to the enhanced spin lattice rate caused by the heavier selenium atom. In addition, an abrupt change in g|| was observed between 150 and 160 K for the Ni(bds)2− salt, which, based on preliminary low temperature X-ray diffraction studies, has been confirmed as a crystalline phase change6. ESR studies of single crystals of the n-tetrabutylammonium salts of nickel (bds)2− and nickel (bdt)2 which have been synthesized in our laboratory and which are large enough to allow single crystal ESR studies to test the above points are reported. An additional reason for this study is that these compounds may serve as the building blocks for the synthesis of a new series of conducting salts based on small cations\ (e.g., alkali metals) in analogy with the recent work of Underhill et al7 on the malonitrile complexes.