Pyrazolyl ring

In some recently discovered tris(pyrazolyl)hydroborato ligands, the 3-phenyl substituent is tethered to the 4-position of the pyrazolyl ring, e.g., tris(2//-benz[G]inda-zol-2-yl)hydroborato. See... 

The novel tetrabasic ligand l,3-bis(5-methylpyrazole-3-carboxamido)propane forms a trinuc-lear Co111 Co11 Co111 complex (196). The tetradentate diamide-pyrazolyl chelates encircle the terminal trivalent metal ions while the central divalent Co is in a distorted tetrahedral environment provided by the four bridging pyrazolyl rings.881... 

FIGURE 10. Molecular structure of [B(Pz)4]2 Sn(Pz = pyrazolyl ring). Reprinted with permission from Reference 82. Copyright (1993) American Chemical Society... 

Polypyrazolylborates have been compared with cyclopentadienyls [23] they are actually multidentate a-ligands coordinating through the nitrogen atoms in the pyrazolyl rings. In a similar manner to the cyclopentadienyl ligand, hydrotrispyrazolylborate (Tp ) may be extensively and diversely functionalized. Two homoleptic bispolypyrazolylborate derivatives Yb(Tp)2, the purple... 

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