Crystal structures of 1′-aminocobaltocenium-1-carboxylic acid chloride monohydrate and of its azo dye 1′-[2-(1-amino-2,6-dimethylphenyl)diazen-1-yl]cobaltocenium-1-carboxylic acid hexafluoridophosphate monohydrate

Abstract

1′-Aminocobaltocenium-1-carboxylic acid chloride, [Co(C5H6N)(C6H5O2)]Cl·H2O, (3), and its azo derivative 1′-[2-(1-amino-2,6-dimethylphenyl)diazen-1-yl]cobaltocenium-1-carboxylic acid hexafluoridophosphate, [Co(C13H14N3)(C6H5O2)]PF6·H2O (5) were obtained from cobaltocenium-1,1′-dicarboxylic acid hexafluoridophosphate by converting one carboxyl group to its chlorocarboxyl derivative followed by chloride/azide exchange, Curtius rearrangement, diazotiation and azo coupling with 2,6-dimethylaniline. 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 supramolecular network including the counter-ion and the water molecule 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 supramolecular network is observed with not only the carboxylic 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 molecule. The hexafluoridophosphate 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

• crystal structure
• cobaltocenium
• azo dye
• amino acid
• metallocene
• metallocenium
• azo coupling