In chemistry, a template reaction is any of a class of ligand-based reactions that occur between two or more adjacent coordination sites on a metal center. In the absence of the metal ion, the same organic reactants produce different products. The term is mainly used in coordination chemistry. The template effects emphasizes the pre-organization provided by the coordination sphere, although the coordination modifies the electronic properties (acidity, electrophilicity, etc.) of ligands.[1]
An early example is the dialkylation of a nickel dithiolate:[2]
The corresponding alkylation in the absence of a metal ion would yield polymers. Crown ethers arise from dialkylations that are templated by alkali metals.[3] Other template reactions include the Mannich and Schiff base condensations.[4] The condensation of formaldehyde, ammonia, and tris(ethylenediamine)cobalt(III) to give a clathrochelate complex is one example.
18-Crown-6 can be synthesized by the Williamson ether synthesis using potassium ion as the template cation.Structure of nickel-aquo nitrate complex of the ligand derived from the templated trimerization of 2-aminobenzaldehyde.[5]
The phosphorus analogue of an aza crown can be prepared by a template reaction.[6] Where it is not possible to isolate the phosphine itself.
Scheme 4. Phosphacrown
^Cotton, Frank Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochman, Manfred (1999). Advanced Inorganic Chemistry (6 ed.). p. 348. ISBN 9780471199571.
^Thompson, Major C.; Busch, Daryle H. (1964). "Reactions of Coordinated Ligands. VI. Metal Ion Control in the Synthesis of Planar Nickel(II) Complexes of α-Diketo-bis-mercaptoimines". J. Am. Chem. Soc.86 (2): 213–217. doi:10.1021/ja01056a021.
^George W. Gokel; Donald J. Cram; Charles L. Liotta; Henry P. Harris; Fred L. Cook (1988). "18-Crown-6". Organic Syntheses; Collected Volumes, vol. 6, p. 301.
^Otilia Costisor, W. Linert "Metal mediated template synthesis of ligands" World Scientific Publisher, Singapore, 2004. ISBN 981-238-813-3
^Fleischer; E. B.; Klem, E. (1965). "The Structure of a Self-Condensation Product ofo-Aminobenzaldehyde in the Presence of Nickel Ions". Inorganic Chemistry. 4 (5): 637–642. doi:10.1021/ic50027a008.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Edwards, P. G.; Haigh, R.; Li, D.; Newman, P. D. (2006). "Template Synthesis of 1,4,7-Triphosphacyclononanes". Journal of the American Chemical Society. 128 (11): 3818–3830. doi:10.1021/ja0578956. PMID 16536558.
In chemistry, a templatereaction is any of a class of ligand-based reactions that occur between two or more adjacent coordination sites on a metal center...
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geometries conducive to reactions either between ligands or involving ligands and other external reagents. A well known metal-ion-templating was described by...
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are detected only rarely. PCR is an enzymatic reaction, therefore, the quality and concentration of template DNA, concentrations of PCR components, and the...
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