Charge-Transfer Interactions of the Higher Valency Halides and Oxyhalides with Aromatic Hydrocarbons. Ball-Plane Interactions. Measurements of Weak Interactions and Literature Review

摘要

The following generalizations are examined in a review of the chemical literature: (1) the covalent higher valency halides, oxyhalides, and oxides of the elements are molecules of high electron affinity, and will demonstrate charge-transfer absorptions with aromatic hydrocarbon donors; (2) as such donors produce firm complexes only in close, plane-to-plane combinations, and since the interactions will be mostly of the 'ball-plane' type for acceptor structures higher than and including the tetracoordinate state, all interactions will be very weak or just contact. Some brief experiments to test these views are described. In particular, the disappearance of color in frozen mixtures is a useful criterion of simple eutectic phase diagrams. Methods of measuring weak associations are discussed, and the spectral techniques outlined here, namely, equilibria studies in solution, temperature effects on absorption intensity, and color changes in the frozen mixtures, are concluded to be among the most discriminating. Although the evidence is incomplete, the proposals seem to be correct, and the weak interactions are discussed in terms of geometric incompatibility. The positions of the charge-transfer transitions and the relative acceptor strengths are examined in terms of the structures of the molecules. (Author)