DETERMINATION OF REACTION PATHS FOR PENTACOORDINATE METAL-COMPLEXES WITH THE STRUCTURE CORRELATION METHOD

Crystal structures potentially deliver far more information than is present in the average structural communication—if sufficient structural data on closely related molecules or molecular fragments are available, it may be possible to infer details of geometric changes occurring along certain reaction pathways for the species of interest. This geometric information is extrapolated from an analysis of the similarities between the structures of the fragment in the various crystalline environments, by a method that is now known as structure correlation analysis. Since it was first proposed twenty years ago, the method has been applied to a large variety of chemical systems, but none have received as much attention as the class of five‐coordinate compounds. Comparative analyses of the structures of pentacoordinate complexes have yielded information about the intimate mechanisms of substitution and addition/elimination reactions at tetrahedral and square‐planar complexes, and about intramolecular isomerizations of five‐coordinate compounds. Since its inception, the structure correlation method has gradually adapted techniques from other branches of science, in particular group‐theoretical and multivariate statistical techniques, which have been shown to be enormously powerful tools for probing geometrically complex systems. This review traces the development of the method of structure correlation and the evolution of these co‐opted techniques, with a specific emphasis on studies of five‐coordinate metal complexes. Copyright © 1994 by VCH Verlagsgesellschaft mbH, Germany