title: Migratory insertion reactions of nickel and palladium σ-alkyl complexes with a phosphinito-imine ligand.
abstract: Ligand exchange reactions have been used for the synthesis of metallacyclic complexes of Ni and Pd of the type [M[upper bond 1 start](CH(2)CMe(2)-o-C(6)[upper bond 1 end]H(4))(P-N)], where P-N is the phosphinito-imine ligand P(iPr)(2)OC(Me)[double bond, length as m-dash]N(2,6-C(6)H(3)(iPr)(2). The protic acid [H(OEt(2))(BAr'(4))] (Ar' = 3,5-C(6)H(3)(CF(3))(2)) selectively cleaves one of the two σ metal-carbon bonds, affording cationic monoalkyl complexes. Nickel monoalkyls stabilized with Et(2)O or MeCN ligands are thermally unstable and spontaneously undergo a decomposition process that ultimately leads to the breakdown of the phosphinito-imine ligand. In contrast, cationic alkylpalladium derivatives are thermally very stable, allowing the isolation of a formally unsaturated monoalkyl complex stabilized by an intramolecular π-arene interaction. Although monoalkynickel and -palladium phosphinito-imine derivatives are inactive as ethylene polymerization or copolymerization catalysts, they readily experience migratory insertion reactions. A palladium chelate arising from the successive insertion of CO and ethylene has been isolated and characterized.
authors.affiliation: Instituto de Investigaciones Químicas. Consejo Superior de Investigaciones Científicas - Universidad de Sevilla, Américo Vespucio, 49, 41092 Sevilla, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Ortiz de la Tabla
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Matas
authors.forename: Eleuterio
authors.initials: E
authors.lastname: Álvarez
authors.forename: Pilar
authors.initials: P
authors.lastname: Palma
authors.forename: Juan
authors.initials: J
authors.lastname: Cámpora