1'-Amino-cobaltocenium-1-carb-oxy-lic acid chloride, [Co(C5H6N)(C6H5O2)]Cl·H2O, (3), and its azo derivative 1'-[2-(1-amino-2,6-dimethylphenyl)diazen-1-yl]cobaltocenium-1-carb-oxy-lic acid hexa-fluorido-phosphate, [Co(C13H14N3)(C6H5O2)]PF6·H2O (5) were obtained from cobaltocenium-1,1'-di-carb-oxy-lic acid hexa-fluorido-phosphate by converting one carboxyl group to its chloro-carboxyl derivative followed by chloride/azide exchange, Curtius rearrangement, diazo-tiation and azo coupling with 2,6-di-methyl-aniline. Both title compounds crystallize as their monohydrates. In the crystal structure of 3, both functional groups lie in the same direction, with the Cp rings being nearly eclipsed, and participate in an extended hydrogen-bonded supra-molecular network including the counter-ion and the water mol-ecule of crystallization. Although the functional groups in 5 are somewhat further apart, bearing a greater torsion angle with the Cp rings now staggered, a similar supra-molecular network is observed with not only the carb-oxy-lic acid and azo groups, but also with the more remote amino group participating in a hydrogen-bonded network, again including the counter-ion and the water mol-ecule. The hexa-fluorido-phosphate ion shows positional disorder. Compound 3 was refined as an inversion twin. In 5, each of the six F atoms is disordered over two sets of sites in a 1:1 ratio.
Keywords: amino acid; azo coupling; azo dye; cobaltocenium; crystal structure; metallocene; metallocenium.