Coordination Chemistry of Scorpionate-type Ligands

Since their discovery in 1966, poly(pyrazolyl)borates (Bpx and Tpx) have been extensively employed as anionic donor ligands in a wide variety of metal complexes. This family of ligands is highly versatile as their steric and electronic properties can be easily modified by changing either the number of pyrazole rings or by substituents thereon or at the boron/carbon center. Trofimenko coined the term ‘‘Scorpionates’’ for poly(pyrazolyl)borates due to their interchange between bidentate and tridentate coordination modes, as the coordination behaviour of the [RR’B(pz)2] ligands closely resembles the hunting habits of a scorpion. In this context, therein we report an overview of recent results obtained with bis- and trispyrazolylborate ligands bearing Br, iPr and Tn substituents in the pyrazole rings (BpBr3, TpBr3, TpiPr,Br, TpTn) towards some CuI, CuII, ZnII, CdII and RuII acceptors, together with the spectroscopic and structural characterization of the relative organometallic complexes.