494191-96-7Relevant articles and documents
Use of the imine-enamine equilibrium in cooperative ligand design
Wambach, Truman C.,Ahn, Jun Myun,Patrick, Brian O.,Fryzuk, Michael D.
, p. 4431 - 4439 (2013/09/02)
The imine-phosphine ligands Ph2PC5H7NAr, where Ar = 2,6-Pri2C6H3, 2,6-Me 2C6H3, were deprotonated using KH to generate the corresponding potassium salts, which were reacted with [(COD)IrCl] 2 to generate the enamidophosphine derivatives (COD)Ir(Ph 2PC5H6NAr) (Ar = 2,6-Pri 2C6H3, 4a; Ar = 2,6-Me2C 6H3, 4b). These complexes were exposed to alcohols, H 2, and CO to generate a series of products, some of which involve protonation of the enamido unit to generate the imine tautomer. The reaction of 4a with isopropyl alcohol or H2 generates the dinuclear hexahydride [(Ph2PC5H7N-2,6-Pri 2C6H3)IrH2]2(μ-H) 2 (5a), while the reaction with primary alcohols generates the dicarbonyl enamidophosphine complex (CO)2Ir(Ph2PC 5H6NAr) (6a). The reaction of the hexahydride 5a with CO generates 6a, for which a mechanism is proposed on the basis of monitoring this reaction as a function of time by NMR spectroscopy. On the basis of these experiments, cooperative ligand effects can be replicated by imine-phosphine ligands by proton transfer to and from the ligand backbone.
