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Solution Chemistry of Complexes. Although much has been learned con cerning the two major categories of co ordination compounds, robust and la bile complexes, research workers are discovering much more concerning these types, D. N. Hume, Massachusetts In stitute of Technology, stated. The robust type, which show little tendency to revert to their simple com ponents, were explored in detail, then neglected for years. They are now once again the object of considerable re search because of the growing impor tance of chelating agents and the cur rent interest in reaction kinetics and mechanism. Labile complexes, which tend to ap proach equilibrium rapidly with their components in aqueous solution, be came better understood with develop ment of Bjerrum's concept of consecu tive complex formation. More recently (here has been a growing interest in polynuclear complexes, particularly of mixed-ligand complexes. Complex Reaction Rates and Sta bility. The rate of a chemical reaction does not necessarily depend on the mag nitude of the over-all driving forces for reactions, R. G. Pearson, Northwestern University, stated. His paper surveyed some of the fundamentals involved in reaction rates and stability of metal complexes. Elaborate electrostatic models for co ordination complexes show deviations
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from linear relationships for reactions with a common mechanism. Changes in mechanism, such as variation in co ordination numbers and geometries of different metal complexes of a given ligand, can lead to large disruptions of the rate-equilibrium parallelism. The amount of rate data for metal com plexes is sparse compared to the amount of equilibrium data, particularly for labile systems. Chelating Agents in Analysis. A knowledge of factors governing the formation and properties of metal che lates is helpful in understanding cur rent applications and in predicting fu ture trends, reported Henry Freiser, University of Arizona. Included are such structural parameters as basicity, electronegativity of bonding atoms, steric considerations, and ionic poten tial and availability of bonding orbitals of metal ions. He also reviewed applications to various types of separation processes. Ion Exchange Separations. In us ing complexing agents in the selective displacement type of ion exchange sep aration of metals, eluting agents are required which are selective in their complexing action, said J. S. Fritz, Iowa State College. One way to improve selectivity is by careful control of pH. A somewhat related topic, anion ex change separations of metal ions, wag discussed by Kurt Kraus, Oak Ridge National Laboratory. He said that he
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Picker X-Ray Corp., 25 South Broadway, White Plains, Ν. Υ., has opened a new research center at Cleveland, the site of its main manufacturing plant (17325 Euclid A v e ) . The photo shows the master-slave manipulator used to encapsu late a highly radioactive wafer of cobalt-60
