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Several pyridine carboxylate complexes of cobalt(I1) and nickel(I1) have been prepared and their spectral and magnetic properties and X-ray powder patterns used to establish their stereochemistry. The cobalt(I1) complex of pyridine-3-carboxylic acid Co[3-py(C0,)],~4H20, whose crystal structure we have previously reported, was used as a model for a consideration of the structural details of these complexes. Like the latter cobalt(I1) derivative, the nickel(I1) complex of pyridine-3-carboxylic acid and the cobalt(l1) and nickel(I1) complexes of pyridine-4-cartioxylic acid and pyridine-3-sulfonic acid, isolated as their tetrahydrates, are formulated as non-classical zwitterions. Comparisons are made with the related pyridine carboxylate complexes of silver(I1).On a prepare plusieurs complexes carboxylate de pyridine de cobalt(I1) et de nickel(I1) et on a utilise leurs proprietes spectrales et magnetiques et leurs spectres de poudres par rayons-)< pour 6tablir leur stereochimie. Le complexe de cobalt(I1) de l'acide pyridine-carboxylique-3 Co[3-py(CO2)],~4H2O, dont la structure cristalline a tte rapportee prCc6demment, a kt6 utilise comme modele dans 1'6tude des details structuraux de ces complexes. Comme le derive du cobalt(I1) precedent, le complexe de nickel(I1) de l'acide pyridine-3 carboxylique et les complexes de cobalt(I1) et de nickel(I1) l'acide pyridine-4 carboxylique et de I'acide pyridine-3 sulfonique, isoles sous forme de tetrahydrates, sont formules comme ttant des zwitterions non-classiques. On compare ensuite ces complexes a ceux de l'argent(II), soient les complexes pyridine carboxylate.

Restriction of theEnvironment of the Dimethylthallium(III) Ion by 'Threading' through a Crown Ether: X-Ray Crystal Structure of Dimethyl(dibenzo[b,k] [ I ,4,7,10,13,16] hexaoxacyclo-octadecin)thall i um (111) 2,4,6-Trinitrophenolate