Synthesis of Crown Ether Ligands and

Metal Complexes that contain them.


Our attention is centered on the synthesis of crown ether-containing transition metal complexes in which catalytic activity and/or product selectivity is "switched" on or off through binding of simple cations by crown ether units.  One project addresses our hypothesis that the migratory insertion reaction depicted in Scheme 1 for a transition metal carbonyl complex can be accelerated by the addition of added cation when R is a crown ether.   The presence of Lewis acids can activate the carbon of metal carbonyl complexes toward nucleophilic attack.   Preliminary studies suggest that the number of intervening methylene groups between the metal site and the benzo-crown ether are critical in providing the correct  conformation for interaction between a CO and the cation trapped within the crown.  Molecular modeling indicates that a three or more methylene groups provide the flexibility required to place the crown ether in a favorable conformation for complexation with a terminal carbonyl group. 







A synthetic route has been devised and a model complex has been prepared

We are now preparing a series of complexes where  x = 3, 4, 5, and 6. When these compexes are in hand the migratory insertion will be investigated both in the presence and absence of added cation.  


Last Modified: 03/19/2013

Chemistry Department
James Madison University
Harrisonburg, VA 22807