Pyrazole-type ligands, complexes

Ovejero, P., Mayoral, M.J., Cano, M. and Lagunas, M.C. (2007) Luminescence of neutral and ionic gold(l) complexes containing pyrazole or pyrazolate-type ligands. Journal of Organometallic Chemistry, 692, 1690-1697. 

Rhodium complexes with pyrazole or pyrazolate-type ligands have been studied as catalysts for hydrogenation of alkenes under ambient conditions in propan-2-ol <87JMOC34l). Hydroquinones... 

Neutral complexes with azolate ligands of the type [AuL(PPh3)], with L representing differently substituted pyrazolates,2251,2366 imidazolates,365,2 69 2370 benzidimidazolates, 71 2372 triazolate,2373 tetraazolate (403),536 or 2,2 -bibenzimidazolates (404),2374,2375 have been prepared. The structure of the [Au(l,2,4-triaz)(PPh3)] is a dimer with Au-,Au interactions (405).23 3 The antimicrobial... 

Trofimenko reviewed his work on poly(pyrazolyl)borate chemistry and pyrazole-derived ligands in 197157 and 19 72.58 In the 1972 contribution Tpx ligands were contained as a separate category. In 198659 Trofimenko reported a summary on the coordination chemistry of poly(pyrazolyl)borates. Its review in 19932 covers the 1984-1993 period and contains the systematic abbreviation system that we employed in this book and which could be adapted to most types of substitution on the Tp ligand, greatly facilitating writing chemical formulas for Tpx complexes. Shaver also commented the Tpx... 

Reactions of the metallocene derivatives of molybdenum with pyrazole lead to the mononuclear complexes of the type 22. Structure 22 shows that it cannot be used as a ligand for the preparation of dinuclear complexes owing to geometric constraints [80JOM( 197)291 83JOM(253)53]. In acetone, an unusual complex 23 is formed [83JOM(253)53]. The bidentate ligand is the product of the reaction of pyrazole and acetone. 

ICA 97)19]. Compound 163 (R = Br) and perchloric acid yield 164, where the monodentate pyrazolate ligand is protonated. Potassium hydroxide regenerates 163 (R = Br). Dicationic complexes of the type 164 can alternatively be produced from [Rh2(r/ -Cp )2(/x-0H)3]Cl04 and perchloric acid in the presence of excess pyrazole, 4-bromopyrazole, 3-methylpyrazole, or 3,5-dimethylpyrazole. 

Organonickel derivatives also offer cases of the -coordination of the substituted hydrotrisfpyrazol- l-yl)borate ligand. For the palladium and platinum complexes, the M(II) M(IV) (M = Pd, Pt) transformation is facile. Organopalla-dium chemistry offers anew type of agostic interactions, C—H - - - Pd, where the C—H bond belongs to one of the pyrazolate rings. Cyclopalladation of various pyrazol-l-ylborates and -methanes does not modify their structure. 

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