The trispyrazolylborate, scorpionate, ligand (pioneered by the late S. Trofimenko) coordinates almost every type of metal ion (p, d, and f block). More recently, trisimidazolylborate analogs of this ligand (pioneered by J. M. Smith) have led to complexes with interesting structure and reactivity. We will describe the use of spectroscopic techniques, primarily EPR, but also optical spectroscopy, including MCD, to study the electronic structure of several paramagnetic, first row transition metal ion (Mn(III, IV), Fe(II), Co(II), and Ni(II)) complexes supported by scorpionate ligands. For such high-spin (meaning with S > 1/2, in this context) complexes, EPR at high magnetic fields (up to 25 T) and correspondingly high frequencies (sub-THz: 95 ? 750 GHz), known as HFEPR, is especially useful. We will discuss how classical ligand-field theory (LFT), as well as more modern, quantum chemical theory (QCT) methods can be used to provide valuable chemical information on these systems.




















Joshua Telser (Roosevelt University)