SOLVENT DONOR AND ACCEPTOR PROPERTIES OF PYRIDINE

Polarographic and cyclovoltammetric measurements on the perchlorates of Li+, Na+, K+, Rb+, Cs+, Tl+, Ba2+ and Ni2+ as well as on the trifluoromethane sulfonates of Zn2+, Cd2+, Pb2+, Cu2+, Cu+, Mn2+ and Co2+ were carried out. The data allowed the evaluation of the different donor behavior of pyridine towards hard, border line and soft cations. The conclusions drawn from electrochemical investigations were supported by Gibbs energies of transfer for cations, which were derived from both electrochemical measurements based on the bis(biphenyl)chromium assumption and from solubility studies based on the tetraphenylarsonium tetraphenylborate assumption. The acceptor properties of pyridine were obtained from the solvatochromic dyes bis(cyano)bis(1,10-phenanthroline)iron(II) and bis(cyano)bis(3,4,7,8-tetramethyl-1,10-phenanthroline)iron(II) and the results were compared with the acceptor number and the ET-value. © 1990 Plenum Publishing Corporation.