Donor and acceptor properties of the solvents tetrahydrofuran and tetrahydrothiophene

Abstract

The donor and acceptor properties of tetrahydrofuran and tetrahydro-thiophene were evaluated by means of electrochemical and spectroscopic methods. Polarographic and cyclovoltammetric data for LiClO4, NaClO4, KClO4, RbClO4, CsClO4, Ba(ClO4)2, AgCF3SO3, TlClO4, Zn(CF3SO3)2, Cd(CF3SO3)2, Cu(CF3SO3)2, Pb(CF3SO3)2, Mn(CF3SO3)2, Co(CF3SO3)2, Ni(ClO4)2·2H2O, oxygen, perylene, ferrocene, and bis(biphenyl)chromium tetraphenylborate in tetrahydrofuran and of TlClO4, CuCF3SO3, Pb(CF3SO3)2, Cd(CF3SO3)2, oxygen, ferrocene and bis(biphenyl)chromium tetraphenylborate in tetrahydrothiophene together with the potentials of the Ag/0.01 M Ag+-ion electrodes in these two solvents are given. Molar Gibbs (free) energies for the transfer from acetonitrile into tetrahydrofuran for Na+, K+, Rb+, Ag+, Tl+, Zn2+, Cd2+, and Pb2+, and for the transfer into tetrahydrothiophene for Ag+, Cu+, Tl+, Cd2+, and Pb2+ were calculated from these data. Visible spectra were obtained for the solvatochromic dyes acetylacetonato(N,N,N′,N′,-tetramethylethylenediamine) copper(II) perchlorate and for 2,6-diphenyl-4-(2,4,6-triphenyl-l-pyridinio)phenoxide, which served as secondary standards to obtain donor and acceptor numbers. The changes in half-wave potentials of the cations vs. bis(biphenyl)chromium(I)/(0) and the Gibbs energies of transfer are discussed on basis of hard and soft donor properties of these two solvents.