Triazolate complexes

The ternary triazole complex [Fe (abptrz)2(tcnq)2] ((132) in Section 5.4.3.6.3 above abptrz = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole) contains the 7,7, 8,8 -tetracyanoquinodimethane (tcnq) radical anion coordinated in trura-positions at unusually short Fe—N distances the tcnq radical ligands are stacked in pairs to give diamagnetic entities. " ... 

IR spectra, 22 177-179 Raman spectra, 22 178, 179 triazole and triazolate complexes, 32 180 trifluoride, structure, 27 90, 91, 92, 95, 97 trifluorophosphine complexes cyclopentadienyl, 29 103 hexakis anion, 29 53-54 [Ni4(0CH3)4(acac)4(CH3OH4)l, 43 323 Nitramide, reaction mechanisms, 22 138, 139 acid catalysis, 22 139... 

Kume S, Kuroiwa K, Kimizuka N. Photoresponsive molecular wires of Fe triazole complexes in organic media and light-induced morphological transformations. Chem Commun 2006 2442-2444. 

Kuroiwa K, Shibata T, Takada A, Nemoto N, Kimizuka N. Heat-set gel-like networks of lipophilic Co(II) triazole complexes in organic media and their thermochromic structural transitions. J Am Chem Soc 2004 126 2016-2021. 

Rates for this reaction may easily be measured by disappearance of azide UV absorption. Most importantly, kinetic saturation behavior is noted with sufficient amounts of the reactants cycloaddition velocity becomes independent of substrate concentration. As is familiar from enzyme catalysis, this indicates complete occupancy of all available cucurbituril by reacting species. In actuality, the rate of the catalyzed reaction under conditions of saturation was found to be the same as that for release of the product from cucurbituril. Such a stoichiometric triazole complex was independently prepared and its kinetics of dissociation were examined by the displacement technique previously outlined, giving the identical rate constant of 1.7xl0 s under the standard conditions. (It is not uncommon for product release to be rate-limiting in enzymic reactions). 

Adducts of triazoles with transition metal salts are usually prepared by direct reactions between the two components involved and frequently precipitate or crystallize spontaneously from the reaction mixture (55,172,194, 202). Complexes containing triazolate anions can usually be obtained from the corresponding transition metal halide, carboxylate, nitrate, or perchlorate complex and an alkali metal (146, 147, 172) or thallium(I) triazolate salt (33). Other routes to triazolate complexes include the direct reactions of metal halides with triazoles in the presence of a base (201) and the treatment of triazole/metal halide... 

This section highlights some of the more important spectroscopic results obtained for triazole and triazolate complexes. 

Infrared data have been tabulated for benzotriazole and a wide range of its transition metal complexes or adducts (172). Far infrared spectra have been recorded for copper(II) benzotriazole adducts and bands at 270-320 cm-1 have been assigned to Cu-N vibrations (172). Infrared absorptions at approximately 825, 800, and 775 cm-1 in the spectra of cobalt(III)/4,5-disubstituted triazolate complexes have been attributed to triazolate ring vibrations (109). Infrared data have been reported and assignments made for palladium and platinum thiatriazoline-5-thionate complexes (37) and for the parent thione (127). Vibrational spectroscopy has been employed in an attempt to determine coordination sites for a range of 8-azapurine complexes (108). 

Relatively little has been reported on the electronic spectra of triazole and triazolate complexes. Copper(II) benzotriazolate adducts and benzotriazolate complexes show ligand-field maxima in the range 12.5-15.9 kK, in agreement with the proposed octahedral coordination geometry (172). Electronic spectra have also been reported for rhodium(I) and iridium(I) benzotriazolate complexes (33). 

To date no triazole complexes appear to have been reported for the scandium, yttrium, and lanthanum group of metals. 

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