title: Supramolecular bidentate phosphorus ligands based on bis-zinc(II) and bis-tin(IV) porphyrin building blocks.
abstract: Selective metal-ligand interactions have been used to prepare supramolecular bidentate ligands by mixing monodentate ligands with a suitable template. For these assemblies pyridine phosphorus ligands and a zinc(II) porphyrin dimer were used. In the rhodium-catalysed hydroformylation of 1-octene and styrene improved selectivities have been obtained for some of the assembled bidentate ligand systems. In the palladium catalysed asymmetric allylic alkylation similar effects were observed; the enantioselectivity increased by using a bisporphyrin template. The preparation of supramolecular catalyst systems was also explored using tin-oxygen interactions. Dihydroxotin(IV) porphyrin and carboxylic phosphorus ligands assemble into supramolecular ligands and the phosphorus donor atom coordinates to transition metals. The stronger oxygen-tin bond, compared to pyridine-zinc does not result in a better performance of the catalyst.
authors.affiliation: van 't Hoff Institute of Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV, Amsterdam, The Netherlands.
authors.forename: Vincent F
authors.initials: VF
authors.lastname: Slagt
authors.forename: Piet W N M
authors.initials: PW
authors.lastname: van Leeuwen
authors.forename: Joost N H
authors.initials: JN
authors.lastname: Reek