Homoscorpionate ligands

As with the earliest examples of C-H insertion, cyclohexane has been a common substrate for evaluation of the effectiveness of new catalysts (Table 1). In contrast to the simple copper catalysts utilized in Scheme 3, the new homoscorpionate ligands of 67 and 69b, developed for this purpose by Dias, Lovely and Perez,... 

Indazole itself and indazoles containing alkyl or aryl substituents in positions 3, 4, 5, and 6 form ligands where boron is bonded to the more hindered N-l which represent a special class of homoscorpionate ligands containing a protective pocket. 

The compound [Li(Tp )(Hpz )]-Hpz is the unique reported lithium compound, structurally characterized, containing a homoscorpionate ligand. It shows a UN4 distorted tetrahedral geometry with a triden-tate Tp (Fig. 2.1). The crystal packing is dominated by hydrophobic methyl-methyl interactions.1... 

The scorpionate tungsten chemistry continues to be very rich and limited to the homoscorpionate ligands. Analogous Mo and W complexes are often reported in the same article tungsten complexes are also described in the previous section, and references to Mo derivatives can also be found in this chapter. 

Also, if the first Rh complex containing a homoscorpionate ligand has been prepared in 1969,393 the Rh(I)Tpx chemistry continues to attract many researchers, likely for its increasing application in C-H bond activation. [Rh(Tpx)(diolefin)],394,395 [Rh(Tpx)(L)2]396-399 (L = CO or PR3), and Rh(III) alkyl complexes of general structure [Rh(Cl)-(CNCH2fBu)(R)(Tpx)]400,401 are the most important classes of compounds investigated until 1999. 

Cu(I) and Cu(II) complexes containing homoscorpionates ligands have been widely reported due to their potential applications in catalysis and enzyme modeling. Homoleptic [Cu(Tpx)2],529,530 dimeric [Cu(Tpx)]231 and [Cu(Tpx)]20,532 [Cu(Tpx)(PR.3)]533,534 and [Cu(Tpx)(CO)]531 species have been characterized with a number of experimental techniques and theoretical calculations. 

Kunishita A, Gianetti TL, Arnold J. Structures, physicochemical properties, and reactivities of cobalt (II) complexes supported by a homoscorpionate tris(pyrazolyl)borate ligand TpPh, Me. Organometallics. 2012 31 372-380. 

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