The Chelate, Cryptate and Macrocyclic Effects
- 1 February 1988
- journal article
- research article
- Published by Taylor & Francis in Comments on Inorganic Chemistry
- Vol. 6 (5-6) , 237-284
- https://doi.org/10.1080/02603598808072293
Abstract
The chelate, macrocyclic, and cryptate effects are analyzed. It is concluded that for all three effects considerable stabilization is derived from the greater basicity induced in donor atoms as ethylene bridges are added. Further considerations of importance in these effects are (1) desolvation effects, where steric constraints to solvation of the donor atoms in the free ligand lead to increased complex stability, (2) enforced dipole-dipole repulsion in the ligand, which is relieved on complex formation, and (3) structural preorganization of the ligand such that the donor atoms in the free ligand are already correctly oriented for complex formation. Only for the chelate effect is entropy of paramount importance, where it is derived from a cratic effect. It is emphasized that the level of preorganization of macrocycles, and to a lesser extent cryptands, is much lower than commonly realized. Newly emerging types of more highly preorganized ligands are discussed.Keywords
This publication has 69 references indexed in Scilit:
- Stability of ammonia complexes that are unstable to hydrolysis in waterInorganic Chemistry, 1985
- Relationship between Lewis acid-base behavior in the gas phase and in aqueous solution. 1. Role of inductive, polarizability, and steric effects in amine ligandsInorganic Chemistry, 1983
- Diaza-crown ethers—II: Stability constants of a cyclic and a bicyclic diaza-polyether with some alkali cations in acetonitrileJournal of Inorganic and Nuclear Chemistry, 1980
- Binding of lithium(1+) ion to Lewis bases in the gas phase. Reversals in methyl substituent effects for different reference acidsJournal of the American Chemical Society, 1978
- Progress toward the development of totally synthetic heme-protein models - the use of substituents to control the oxidation-reduction properties of metal ions in complexes with macrocyclic ligandsJournal of the American Chemical Society, 1976
- Crystal structure analyses of 1,4,7,10,13,16-hexaoxacyclooctadecane and its complexes with alkali thiocyanatesActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials, 1974
- Lincomycin. V. Amino acid fragmentJournal of the American Chemical Society, 1967
- Proton Affinities and the Methyl Inductive Effect1Journal of the American Chemical Society, 1965
- The Basicity of PhosphinesJournal of the American Chemical Society, 1960
- A Proposed Approach to the Chelate Effect1Journal of the American Chemical Society, 1954