Biological and Catalytic Applications of Metal Complexes Based on Scorpionate –type Ligands

Since poly(pyrazolyl)borates were first synthesized by Trofimenko in the hlate 1960s, numerous papers have been published describing these ligands. Poly(pyrazolyl)borates and their analogues are also known as scorpionate ligands and, apart from Trofimenko himself, several authors have reviewed their coordination chemistry and applications in catalysis, bioinorganic model systems, metal extraction, and biomedicine. A useful property of these N3-donor tripodal ligands is the ability to tune both their electronic and steric properties by adding the desired R substituents to control steric bulk and donating ability. We report here the chemistry of a number of scorpionate ligands (Tpx, Tpms, bpza, H4-nC(pzx)n) with different transition metal ions of group 8-12 elements, of diverse electronic and stereochemical predilections, together with X-ray structure determinations of their metal complexes, in order to better define the role and extent of the substituent in the heterocyclic rings in determining the coordination behaviour.