651302-83-9Relevant academic research and scientific papers
Ruthenium-stabilized low-coordinate phosphorus atoms. p-cymene ligand as reactivity switch
Menye-Biyogo, Richard,Delpech, Fabien,Castel, Annie,Pimienta, Veronique,Gornitzka, Heinz,Riviere, Pierre
, p. 5091 - 5101 (2008/10/09)
A detailed comparative study of the structural and spectroscopic features and of the reactivity of ruthenium phosphinidene complexes (η6- Ar)(PCy3)Ru(PMeS*) (2a, Ar = p-cymene; 2b, Ar = benzene) has been undertaken. The structures of complexes 2a and 2b have been determined by single-crystal X-ray diffraction and display similar features. Both compounds possess identical chemical behavior toward Broensted acids such as HBF 4: protonation of the phosphinidene ligand yields the new cationic complexes [(η6-Ar)(PCy3)Ru(PHMes*)]BF 4 (3aBF4, Ar = p-cymene; 3bBF4, Ar = benzene), which exhibit an unprecedented phosphenium-bearing hydrogen substituent. 3aBF4 has been characterized using X-ray diffraction techniques. The lone pair of the phosphorus atom of the phosphinidene ligand remains also accessible to the Lewis acid BH3: the reactions of 2a and 2b with borane give the adducts (η6-Ar)(PCy3)Ru[P(BH 3)MeS*] (4a, Ar = p-cymene; 4b, Ar = benzene). In the presence of the larger borane BPh3, no reaction occurs until water is introduced in the reaction vessel. This results in the generation of [(η6-Ar) (PCy3)Ru(PHMes*)]BPh3OH (3aBPh3OH, Ar = p-cymene; 3bBPh3OH, Ar = benzene) presumably through protonation of 2a and 2b by the previously unknown adduct H2O-BPh3. Phosphinidene complexes react also with electrophilic alkylating reagents such as organic iodides provided the alkyl substituent is small. Treatment of 2a and 2b with 1 equiv of methyliodide leads to the alkylation at the phosphinidene center and yields the phosphenium complexes [(η6-Ar)(PCy 3)Ru(PMeMes*)]I (5a, Ar = p-cymene; 5b, Ar = benzene). Examination of the reactivity toward electron-rich reagents such as the alkynes RCCH (R = Me3Si, Ph) yields unexpected results: 2a instantaneously reacts to generate phosphaindane complexes 6 and 7, whereas no reaction occurs when using 2b. A detailed kinetic study provides evidence for a dissociative mechanism involving the release of the phosphine ligand in 2a and explains its specificity. The /?-cymene ligand in 2a acts as a reactivity switch due to the higher steric hindrance of this arene.
Ruthenium-Stabilized Low-Coordinate Phosphorus Atoms: Structural Evidence for Monomeric Metaphosphate
Menye-Biyogo, Richard,Delpech, Fabien,Castel, Annie,Gornitzka, Heinz,Riviere, Pierre
, p. 5610 - 5612 (2007/10/03)
Monomeric metaphosphonate is generated and stabilized within the coordination sphere of a ruthenium atom. The π system of a PO moiety coordinates to the transition metal center and this allows thermodynamic stabilization to give the first structural evidence for monomeric dioxophosphorane.
