Polypyrazolylborates preparation

Polypyrazolylborates metal complexes, 2, 87,245-257 bidcntatc. 2,246 biological applications, 2.255 preparation. 2, 246 tridentate, 2,247 Polypyrazolylgallates... 

Despite the vast interest shown by coordination chemists in polypyrazolylborate ligands (17) since their discovery in 1966 few complexes of chromium(III) with these ligands have been mentioned in the literature. The complex [ B(pz)4 2Cr]PF6 (147) may be prepared by either of the routes outlined in Scheme 89.657... 

Trofimenko69 has reviewed the preparation of polypyrazolylborate ligands and the syntheses of metal complexes containing such ligands. An update has also appeared.70... 

From a coordination point of view, Complex 75 and the related ruthenium complex [(ij6-p-cymene)Ru(pz)2(Hpz)], 76 (7), are comparable to protonated polypyrazolylborates RB(pz)2(pzH) (R = H or pz) (12). The formal similarity between the tris(pyrazolyl)borate anion and the deprotonated form of the iridium complex 75 suggested the preparation of heterodinuclear complexes by using 75 as a building block. Thus, heterodinuclear (n-pz)2 complexes of the formula [(C5Me5)(pz)Ir(/i-pz)2M(PPh3)] (M = Cu, 77 Ag, 78 Au, 79) were obtained (96). 

The success of polypyrazolylborates prompted the development of the coordination chemistry of polyazolylmethanes, the neutral counterpart of anionic borates <86JCS(D)645>. This interest resulted in the preparation of a large family of ligands whose principal representatives are shown below... 

Polypyrazolylborate Ligands.14 Anionic ligands of the types (21-XXX) and (21-XXXI) are relatively easy to prepare and have some interesting and... 

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