Half-wave potential Subject

The use of the Hammett equation has also been extended to several new types of applications. Since these are not germane to the subject matter of the present chapter, we wiU simply mention work on applications to ethylenic and acetylenic compounds the various applications to physical properties, such as infrared frequencies and intensities, ultraviolet spectra, polarographic half-wave potentials, dipole moments,NMR and NQR spectra,and solubility data and applications to preparative data and biological activity. 

Ketonate complexes of Ru are reported in a number of papers. The parent complex [Ru(acac)3] has been subject to a polarized neutron diffraction study at 4.18 K, to powder neutron diffraction studies and to single-crystal structure determinations at 293 K, 92 K, and 10.5 K. The structure is disordered at all temperatures. Measurements of the magnetic susceptibilities (at 2.5 K and 300 K) have been made along different crystal axis directions, and the results analyzed. An investigation of the relationships between ionization potentials and half-wave potentials of a series of tris(/3-ketonate)Ru complexes has been reported, and the electrochemical properties of [Ru(acac)3] in chloroaluminate molten salt media have been reported. The reduced species [Ru(acac)3] can react with AICI4 reduction by bulk electrolysis of a small amount of [Ru-(acac)3] in the melt yields [RuClg]. ... 

Polarographic reduction of the parent gave a value for the half-wave potential (E1/2 = -0.85 v) which is intermediate between the values for quinoxaline ( 1/2 =-1.09 v) and pteridine ( 1/2 =-0.52 v). The electrochemical reduction of substituted pyrido[2,3-fc]pyrazines has been the subject of a recent study. Along with other fused pyrazine systems, the... 

The ruthenium compound also has been prepared and displays similar properties, although it has not yet been the subject of an x-ray study. Bis-indenylcobalt, the first member of the series to be prepared, has a structure similar to the iron analogue on the basis of a comparison of x-ray powder photographs. This latter compound can be readily oxidized to give the quite stable Co(III) compound which, like the cobalticinium ion, may be precipitated as the triiodide, tribromide picrate, or perchlorate. The perchlorate exhibits a well-defined polarographic reduction wave at —0.6 V vs SCE. The corresponding half-wave potential for cobalticinium perchlorate is — 1.16 V. Thus the annulation of a benzene ring produces a very marked decrease in the reduction potential and, conversely, the oxidation of the new compound to the ion should become more difficult. 

---