Synthesis of Scorpionate Ligands

Bpx Reaction of substituted pzx and MBH4 in refluxed anhydrous DMF (M = Li, Na or K). Recrystallization from aromatic high-boiling solvents. 2.3 120-130°C 

Tpx Hpzx liquid Neat-reaction with distillation of the excess pyrazole to prevent pzTpx formation. Required emanating hydrogen measurement. 4 170-190°C 

Tp3R Hpz3R reflux, with rapid stirring in 3 or 4-methylanisole. 3.5 Boiling T 

5R Hpz3R,5R Neat reaction with sublimation of the excess pyrazole. No pzTpx formation. 6-8 180-220°C 

The reaction of MBH4 with Hpzx can be used, through careful temperature control, to yield bis-, tris-, and in the case of 5-unsubstituted pyrazoles, tetrakis(pyrazolyl)borates. Synthesis of the parent ligands Bp, Tp, and pzTp has been detailed by Trofimenko.131 

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