Pyrazole group

Recently, the pyrazole group containing bisphenols have been synthesized from activated aromatic dihalides and 3,5-bis (4-hydroxy phenyl)-4-phenyl pyrazole or 3,5-bis(4-hydroxy phenyl)-1,4-diphenyl pyrazole. A novel synthesis of imido aryl containing bisphenols has been reported [32]. N-substituted l,4-bis(4-hydroxy phenyl)-2,3-naphthalimides were prepared from phenolphthalein and copolymerized with aromatic sulfone or ketone difluorides to obtain the poly(imidoaryl ether) sulfones/ ketones. 

Tri- and tetraaza macrocycles A-functionalized with imidazole and pyrazole groups have been coordinated to zinc. The zinc complexes of functionalized 1,5,9-trizacyclododecane and 1,4,8, 11-tetraazacyclododecane have been synthesized, (76) and (77).680-685 The formation constants with the mono-armed 1,5,9-triazacyclododecane were calculated and found to be higher than for the non-functionalized macrocycle and coordination was demonstrated to be through four nitrogen... 

The 12-membered tetraaza-macrocyclic ligand with four pendant pyrazole groups, L6, was synthesized by the reaction of l-(hydroxy-methyDpyrazole with 1,4,7,10-tetraazacyclododecane in MeCN. The Ni(II) complex [NiLe]I2 formed a distorted octahedral structure with... 

The two platinum complexes 478 and 479 are less fluxional, the pzTp complex 478 being stereochemically rigid below 110 °C, above which it becomes unstable in solution, while for the Tp analogue 479 equivalence of the pyrazole groups is achieved at 85 °C. This equilibration slows at ambient temperature, but poor solubility below 10 °C precluded acquisition of limiting spectra. 

The formulation of 379+, 515+, and 516+ as 5-coorinate silyldihydrides was established on the basis of a single crystal X-ray diffraction study of 379+ (Figure 7)127 and characteristic spectroscopic data, viz. 1H NMR resonances associated with (i) the NH of the protonated pyrazole group (9-10 ppm) and (ii) a discrete terminal hydride (—15 to —17 ppm) that... 

This latter formulation may give access to metal derivatives in which such a di(l-pyrazolyl)borate unit rves as a chiral ligand, i.e., by employing a C-substituted pyrazole as donor molecule. There exists only one report in the literature on forming poly(l-pyrazolyl)borate ions containing two different pyrazole groups, which were obtained in quite laborious manner... 

The presence of the bridging pyrazolate group seems to be an essential requirement in order to stabilize the methoxobridges. 

Scheme 11. Neutral and cationic ruthenium complexes containing unidentate pyrazolate groups have been obtained by using the dinuclear complex Ru(/>-cymeme)CI, ((i-CI)] or the /3-diketon-ato complex Ru(/>-cymene)(acac)Cl] as starting materials. Adapted from (7).]...

This compound was readily prepared from [U(C5H5)3C1] and Na(pz). The U —N distances are 2.40 and 2.36 A. The reason for such a 0.04-A difference appeared unclear. The molecular structure consists of discrete U(CsH5)3(pz) molecules in which the U lv ion is coordinated by three 7j5-(C5Hn) rings and by the two nitrogens of the pyrazolate group (Fig. 15). 

Transition metal complexes containing the pyrazolate group as anionic noncoordinating ligand, although rare, have been reported (5). They are undoubtedly of lesser importance and will not be further discussed. 

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