Relations between Catalyst Structure and Effectivity

If one plots the 8rei ( Co) values against the Arrhenius energies of activation determined for the [RcpCo(cod)] and [(R-indenyl)Co(cod)] catalysts, then an almost linear correlation is found (Fig. 6). The linear relationship between the Arrhenius energy of activation and 8rei( Co) can also be expressed by the regressional Eq.(48), 

The observed differences in the catalytic properties of the R-cpCo complexes might be explained by steric, electronic, or field effects of the substituent. It is generally accepted that the replacement of H by R alters 

The structure-activity relationship for cobalt catalysts in the pyridine synthesis can be summarized in the following manner If the substituent R is a donor, the Co-NMR signals are shifted to higher field and the catalytic activity decreases. If R is an acceptor, the Co-NMR signal is shifted to lower field and the activity increases. Donor substituents are oriented orthogonal to complexed cod in the catalyst precursors acceptors are oriented parallel. The deformation of the spherical charge distribution about cobalt is also dependent on the nature of R. 

Aresta, M. Rossi, and A. Sacco, Inorg. Chim. Acta 3, 227 (1969). 

Gmelin s Handbuch der anorganische Chemie, Erg zungs Werk, 8th ed., vol. 6, Part II, 118. 1973. 

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VI. Relations between Catalyst Structure and Effect vity. 214... 

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