Trinuclear pyrazolate complex

Kim, S.J., Kang, S.H., Park, K.-M., Kim, H Zin, W.-C., Choi, M.-G. and Kim, K. (1998) Trinuclear Gold(l) Pyrazolate Complexes Exhibiting Hexagonal Columnar Mesophases with Only Three Side Chains. Chemistry of Materials, 10, 1889-1893. 

In the crystal, most trinuclear carbeniate complexes are known to be stacked with close aurophilic interactions, and organic 7r-acids can be intercalated into these stacks.252 Similar intercalation takes place with the cations of simple silver and thallium(i) salts. The cations become attached to form polymetallic core units through metallophilic bonding. With the trinuclear silver pyrazolates, both metal and ligand exchange have been observed to give new stacks of trinuclear units.254... 

The interest for pyrazolate complexes containing the pz group as a mono-dentate ligand arises because of their recognized usefulness in the synthesis of dinuclear and trinuclear heterometallic derivatives. The mononuclear complex... 

Polynuclear Copper(l) Catalysts. Apart from mononuclear copper-catalyzed cyclopropanation, more recently polynuclear copper catalysts have been demonstrated to give characteristic diastereoselectivity. [Cu(dtbpz)]4, derived from 3,5-di-tert-butylpyrazole, gave high transicis ratio of 88 12 with slyrene and nonbulky EDA (19). In contrast, trinuclear triangular complexes, [Cu3( i3-OH)()u-pz)s(MeCOO)(MeO)(Hpz)] (Hpz = pyrazole), gave the same cyclopropanes in cis selectivity (trans cis = 38 62) (20). 

Finally, NHC complexes of copper, formed in situ from the hnidazolium salt and CuBr have been used in the monoarylation of aniline [167]. Trinuclear Cu(I) catalysts have been applied to the arylation of pyrazoles, triazoles, amides and phenols [168] (Scheme 6.50). 

Au-C bonds, mixed metal gold-silver dimers of planar, trinuclear complexes are readily formed by mixing gold(I) carbeniates and gold(I) benzylimidazolates with silver(I) pyrazolates in stoichiometric ratios. The complexes retain the ligands associated with the metal atoms of the starting materials. 

Barbera, J., Elduque, A., Gimenez, R., Oro, L.A. and Serrano, J.L. (1996) Pyrazolate Golden Rings Trinuclear Complexes That Form Columnar Mesophases at Room Temperature. Angewandte Chemie... 

Other oligomeric complexes are obtained with nitrogen donor ligands including amides, such as [Au4 NSiMe3)3 4] [226], or formamidates such as [Au4 (NPh)2CH 4] [227], triazenides, such as [Au4 (NPh)2N 4] [228], or pyrazolates, such as the trinuclear species commented above or the hexanuclear [Au6(2-5-Ph2pz)6] [229]. 

The corresponding pyrazole mononuclear derivatives [AuCl(pzH)] have been prepared with the same ligands (Figure 7.41) [38]. Only the monosubstituted non-mesomorphic pyrazole leads to a liquid crystal, not the disubstituted mesomorphic ligand. The complex displays a SmA mesophase on cooling to 69.2 °C, although this is mixed with some crystallization. Moreover, this derivative is luminescent at 77 in the solid state. In addition, the corresponding trinuclear and mononuclear derivatives, namely [ Au(pz) 3] and [Au(Hpz)2]+, which could be expected to be liquid crystals are non-mesomorphic. 

With the previously demonstrated ability of trinuclear gold(I) pyrazo-late complexes that possess long-alkyl chains to form columnar mesophases [119-121], Aida and co-workers synthesized a series of luminescent Au3 complexes bearing dendritic poly(benzyl ether) functionalized pyrazole ligands [122]. By controlling the dendron generation, superhelical fibres with extensive inter molecular Au3 stacking could be obtained, which resulted in an... 

Photolysis of the trinuclear complex Ru3(CO)i2 with hydrogen halides (HCl, HBr and HI) has been shown to give high yields of (p-H)(p-X)Ru3(CO)io (X = C1, Br, With pyrazole, Ru3(CO)i2 gives a substitution product... 

A series of dinuclear and cyclic trinuclear Pt(ii) complexes is prepared by combining C,A-chelating aromatic ligands with pyrazolate and benzimidazolate ligands 512 and 513." The complexes show a red-shift of the emission peaks compared with the ligand. 

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