The reaction of the organometallic acid [(η5-C5H4COOH)2CoIII]+ with HBr and HI.: Preparation and characterisation of [(η5-C5H4COOH)2CoIII]Br and [(η5-C5H4COOH)2CoIII]I and hydrogen bridges between cations

The water soluble dicarboxylic cationic acid [(eta(5) -C5H4COOH)(2)Co-III](+) (1) as its Cl- salt has been treated thermally to produce the neutral zwitterion [(eta(5)-C5H4COOH)(eta(5)-C5H4COO)Co-III] (2). 2 reacts with HBr in water solution to yield the bromide salt of the dicarboxylic acid [(eta(5)-C5H4-COOH)(2)Co-III]Br, 1Br. Preparation of the iodide [(eta(5)-C5H4-COOH)(2)Co-III]I, II, has been achieved by direct oxidation of [(eta(5)-C5H4Me)(2)Co-III]OH with KMnO4 immediately followed by reaction with HI. The crystal structures of 1Br and 1I have been determined by single crystal X-ray diffraction. The hydrogen bonding interactions between the acid cations and between the acid cation and the halide ions, have been investigated. (C) 2003 Elsevier Science B.V. All rights reserved..