2,6-Dicarboxylate pyridine, complexes

Mesoionic 4-amino-l,2,3,5-thiatriazoles constitute the only class of mesoionic 1,2,3,5-thiatriazoles known. They are prepared by the reaction of l-amino-l-methyl-3-phenylguanidine with approximately 2 equivalents of thionyl chloride with pyridine as solvent (88ACS(B)63>. They are obtained as the yellow 1 1 pyridine complexes (17). The dark-violet mesoionic 1,2,3,5-thiatriazole (18) was liberated on treatment with aqueous potassium carbonate (Scheme 3). The structure is established on the basis of elemental analysis and spectroscopic data. In particular, the IR spectrum is devoid of NH absorptions. Compound (18) exhibits a long-wavelength absorption at 463 nm in methanol. When mixed with an equivalent amount of pyridinium chloride, complex (17) is formed and the absorption shifts to 350 mn. The mesoionic thiatriazoles are sensitive towards mineral acids and aqueous base and although reaction takes place with 1,3-dipolarophiles such as dimethyl acetylene-dicarboxylate, a mixture of products were obtained which were not identified. 

Sulfonation was carried out by heating the asphalt with sulfur trioxide-trimethyl amine complex or sulfur trioxide-pyridine complex at temperatures near 135°C. Sulfamic acid treatment was also included in this series. Many other reagents were evaluated such as methyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, 2-dimethyl-aminoethyl methacrylate, 2-vinylpyridine, 4-vinylpyridine, tetrahydro-phthalic anhydride, norbomene dicarboxylic anhydride, and phthalic anhydride. 

Bu2Sn(lV)] complexes formed for pyridine mono- and dicarboxylic acids (Figure 20) containing -COO group(s) and aromatic N donor atom were prepared. 

Another feature ofthe spore is the presence of pyridine 2,6-dicarboxylic acid (DPA) (Fig. 1.10) occurring as a complex with calcium, which at one time was implicated in heat resistance. The isolation of heat-resistant spores containing no Ca-DPA has refuted this hypothesis. 

The hydrolysis of esters by the nickel derivative (271) provided an early example of the use of a metal-capped cyclodextrin as a catalyst (shown here as its p-nitrophenyl acetate inclusion complex) (Breslow Overman, 1970 Breslow, 1971). The synthesis of this host involves the following steps (i) covalent binding of the pyridine dicarboxylic acid moiety to cyclodextrin, (ii) coordination of Ni(n) to this species, and (iii)... 

In the presence of the dioxomolybdenum complex M0O2 (dipic) (HMPA) (dipic = pyridine-2,6-dicarboxylate, HMPA = hexamethylphosphoramide), 2-methylhex-2-ene and phenylhydroxylamine produce the amine 194 in 52% yield other alkenes react analogously199. 

Cyclohexaamylose continued) mono-6-O-tosyl-, preparation of, 23 250 pyridine-2,5-dicarboxylic acid derivative, catalytic action of, 23 251 separation of, by complexing, 23 214 structure, stereochemistry and physical properties of, 23 210-213... 

More advanced semiempirical molecular orbital methods have also been used in this respect in modeling, e.g., the structure of a diphosphonium extractant in the gas phase, and then the percentage extraction of zinc ion-pair complexes was correlated with the calculated energy of association of the ion pairs [29]. Semiempirical SCF calculations, used to study structure, conformational changes and hydration of hydroxyoximes as extractants of copper, appeared helpful in interpreting their interfacial activity and the rate of extraction [30]. Similar (PM3, ZINDO) methods were also used to model the structure of some commercial extractants (pyridine dicarboxylates, pyridyloctanoates, jS-diketones, hydroxyoximes), as well as the effects of their hydration and association with modifiers (alcohols, )S-diketones) on their thermodynamic and interfacial activity [31 33]. In addition, the structure of copper complexes with these extractants was calculated [32]. 

The Ni - and Zn " " -complexes of phenyl and salicyl esters of pyridine-2,6-dicarboxylic acid [50a and b] hydrolyse much faster than the uncomplexed esters (Breslow and McAllister, 1971) the rate of hydroxide ion catalysis of the Ni " -complexes increases 9300... 

Reaction of the m-nitrophenyl ester of pyridine-2,5-dicarboxylic acid with cyclodextrin (see Section 3) gives a picolinate ester [52] of a cyclodextrin secondary hydroxyl group (Breslow, 1971 Breslow and Overman, 1970) which will bind metal ions or a metal ion-pyridine carboxaldoxime complex. Such a complex will catalyse hydrolysis of p-nitrophenyl acetate bound within the cyclodextrin cavity leading to a rate constant approximately 2000-fold greater at... 

RUj(0)g(R-py) (R-py=4-fertbutyl pyridine (4- Bu-py), pyridine-3-carboxylate (nicotinate, nic), pyridine-4-carboxylate (isonicotinate, isonic) and pyridine-3,4-dicarboxylate (cinchonomeronate, cine) are made from (R-py) in CCl with RuO vapour the products are brown-green and of low solubility the 4-ferf-butylpyridine complex is dark red. The vibrational spectra of Ru2(0)g(4- Bu-py) show u"(Ru(0)3) at 822 cm" (Raman) and u "(Ru(0)3) at 815 cm" (Raman) [241]. 

The complexes Ru(pydic)(tpy), Ru(pydic)(pybox-R ) (pydic=pyridine-2,6-dicarboxylate, pybox-Rj=chiral bis(oxazolinyl)pyridines with R=PP, Ph (Fig. 1.37) [105] epoxidised trani-stilbene (as complex/PhlO, Ph OAc), TBHP or OJ CHjClj). Asymmetric oxidations of trani-stilbene were similarly achieved in toluene, benzene and CH Cl with e.e. values from 40-80% cf mech. Ch. 1) [53, 54, 81,97]. Asynunetric epoxidations of rranx-stilbene, styrene, tranx-fl-methylsty-rene and 1-hexene were catalysed by [RuCl(SOMePh)(bpy)j] /TBHP or Ph(IOAc)y CHjCy40°C e.e. values of 33-94% were obtained of the (R. R) forms of the epoxides of tra i-stilbene, tranx-P-methylstyrene [52]. The system Ru(CO)(TPP)/ (CljpyNO)/HBr/C H epoxidised fullerene (C ) to 1,2-epoxy[60]fullerene with 1,2 3,4 di-epoxy and 1,2 3,4 9,10 h- 1,2 3,4 11,12 tri-epoxy species [106]. 

Renaud, F. Piguet, C. Bernardinelli, G. Biinzli, J.-C. G. Hopfgartner, G. In search for mononuclear helical lanthanide building blocks with predetermined properties lanthanide complexes with diethyl pyridine-2,6-dicarboxylate. Chem. Eur. J. 1997, 3(10), 1660-1667. 

Complexes with 2-hydroxycarboxylic acids, pyridine-2-carboxylate, and dicarboxylates are described in Sections II,C,6,c, II,C,4,f, and II,C,6,p, respectively. 

See (239) for the atom labelling. b The sense of distortion of CuN402 is different in this complex (see ref. 553). This complex is dimeric. d pydca = pyridine-2,6-dicarboxylate. e dmphen = 2,9-dimethyl-l,10-phenanthroline. 

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