QUANTITATIVE AND STRUCTURAL INVESTIGATIONS OF HYDROGEN-BONDING INTERACTIONS IN ANION-BINDING OF MONO-SUBSTITUTED AND 1,1'-BIS-SUBSTITUTED ARYL COBALTOCENIURN RECEPTORS

New acyclic monosubstituted aryl cobaltocenium derivatives, functionalised with additional hydrogen-bonding amine groups have been prepared. Quantitative investigation of the anion-binding properties by H-1 NMR spectroscopy and electrochemical methods shows enhanced binding believed to be due to amine group participation in hydrogen bonding. Similar recognition studies on 1,1'-bissubstituted aryl cobaltocenium analogues indicate an order of magnitude selectivity for the dihydrogenphosphate anion over simple halide anions. The importance of hydrogen bonding is also illustrated by the first single-crystal structure showing the anion complex of a cobaltocenium receptor.