title: Chemistry of bridging phosphanes: CuI dimers bearing 2,5-bis(2-pyridyl)phosphole ligands.
abstract: Bis(2-pyridyl)phosphole 1 reacted with Cu(I) sources giving rise to dicationic or neutral dimers 2,3. In these derivatives, 1 acts as a 1kappaN:1,2kappaP:2kappaN donor with a symmetrically bridging P centre. X-ray diffraction studies of these species revealed no constraint due to the unusual coordination mode of the P donor. A comparative study with a monometallic Cu(I) complex in which 1 acts as a P,N chelate is presented. The acetonitrile ligands of the dicationic complex 2 can be displaced by a variety of donors. Bipyridine (bipy) acts as a chelating donor, while 1,1'-bis(diphenylphosphino)methane (dppm) and bis(2-pyridyl)phosphole 1 behave as bridging ligands. By using dppm and 1, the complexes arising from the stepwise displacement of the acetonitrile ligands of complex 2 can be isolated. X-ray diffraction studies performed on these novel complexes revealed that the P centre can easily switch from a bridging to a semibridging coordination mode. Of particular interest, within the same unit cell, complexes with P centres exhibiting bridging and semibridging coordination modes are observed. This switching can be induced by weak effects such as a different conformation of the incoming ligand. Cu(I) dimers assembled by 1 are air-stable derivatives that are not water sensitive. Hydrolysis of the PF(6) (-) counterion occurs under drastic conditions and results in the formation of a PO(2)F(2) fragment coordinated to a Cu(I)-1 fragment.
authors.affiliation: Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Campus de Beaulieu, Rennes Cedex, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Nohra
authors.forename: Elena
authors.initials: E
authors.lastname: Rodriguez-Sanz
authors.forename: Christophe
authors.initials: C
authors.lastname: Lescop
authors.forename: Régis
authors.initials: R
authors.lastname: Réau