Magneto-optical studies of liquid mixtures. Part 4.—Additivity of the faraday effect, the magnetic rotation dispersion constant and the excess magnetic rotation in binary liquid mixtures

Abstract

The values of molar magnetic rotation, Λ_m, molecular rotativity, Ω_m, and magnetic rotation dispersion constant, K_m, are presented for 72 organic compounds and their values compared with other physical properties such as molar refraction, molar polarisation and magnetic susceptibility. The magneto-optical parameters indicated three classes of compound amongst those studied, namely, aliphatic compounds, aromatic compounds other than amines and aniline and its derivatives. The molecular additivity of Λ_m, Ω_m and K_m was tested using a set of empirically derived partial values. For more than two-thirds of the compounds studied the agreement between calculated and observed magneto-optical parameters was better than 10%. The various extents of deviation for the remaining compounds were rationalised in terms of their known molecular properties. Many of the compounds had been previously studied in mixtures with CCl₄ and the excess magnetic rotation, α_E, was correlated with the formation of charge-transfer complexes. It was found in the present work that the formation of lone-pair complexes and π-complexes could be correlated with the K_m values of the donors.