Issue 6, 1998

Supramolecular interactions between Co(CN)5(SO3)4– and polyammonium macrocyclic receptors

Abstract

The acid–base properties as well as the photochemical reactivity of the co-ordination compound K4[Co(CN)5(SO3)] in the presence of three polyammonium macrocyclic receptors were studied in aqueous solution. The pKa of the free complex (3.9) (sulfite deprotonation) changed to pKa <0.5 upon complexation with the receptors. The quantum yield for sulfite photoaquation of the free complex in the basic form (Φ = 0.85 ± 0.09) decreased to 0.05 ± 0.01, 0.12 ± 0.03 and 0.45 ± 0.09 in the presence of [24]aneN8H88+, [30]aneN10H1010+ and [32]aneN8H88+, respectively. For the acidic form of the free complex (Φ = 0.40 ± 0.05) the quantum yield was not affected by supercomplexation with [32]aneN8H88+. For the adducts formed from the other two macrocyclic receptors it was not possible to evaluate the quantum yields of the acidic forms, because protonation was not complete even at very high proton concentrations. The results were interpreted in terms of second-sphere interactions involving hydrogen bonding between the complex and the macrocycles. In the case of [32]aneN8H88+, the experimental results are compatible with a structure in which the cyanides are involved in hydrogen bonding but the sulfite ligand is not. In the two other supercomplexes the sulfite ligand seems to be involved in hydrogen bonding.

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1998, 1005-1010

Supramolecular interactions between Co(CN)5(SO3)4– and polyammonium macrocyclic receptors

A. Jorge Parola, F. Pina, M. Francesca Manfrin and L. Moggi, J. Chem. Soc., Dalton Trans., 1998, 1005 DOI: 10.1039/A708805A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements