Polypyrazolylborate ligands synthesis

By far the most common synthesis technique is to introduce polypyrazolylborate ligands by replacing halide groups. As might be expected this leads to a great variety of complexes. In some... 

The synthesis of Tp ligands that contain different substituents on the 3- and 5-positions on the pyrazole have been reported, For example, Graham and co-workers reported the synthesis of tris[3-(trifluoromethyl)-5-methyl]pyrazole borate. However, the most commonly used polypyrazolylborate ligands are substituted symmetrically at the 3- and 5-position. The unsymmetrical systems can undergo shifts of boron between the two nitrogens, and this shift scrambles the 3- and 5- positions. ... 

From their genesis, polypyrazolylborates have found applications in many areas of chemistry such as the modeling of active sites of met-alloenzymes, perspective materials, organic synthesis, homogenous catalysis, or as spectator ligands in the development of reactive metal centers. A number of miscellaneous items will also be discussed in this chapter. 

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