Phosphine Oxides and Related Chalcogenides

1 Preparation. - The diphosphines (223) can be oxidised to the related dioxides on treatment with oxygen or hydrogen peroxide. Treatment of the diphosphine (223, R = Ph) with an excess of sulfur in hot toluene affords the corresponding bis(sulfide). X-ray studies of representative dioxides and the above disulfide reveal considerable steric strain in the molecule, resulting in out of plane displacement of phosphorus atoms. The reaction of (223, R = Ph) with an 

The reactions proceed with retention of configuration at phosphorus. Various classical routes to alkylphosphine oxides have been applied in the synthesis of a range of potentially chelating and pincer-like ligands, e.g., (233), the binaphthyl system (234), the hybrid phosphine oxide-N-oxide (235), and the chiral pyridine bis(phosphine oxide) (236). A route to diarylmethylphosphine oxides is afforded by the palladium-catalysed reaction of aryl bromides with tet-rakis(hydroxymethyl)phosphonium chloride in the presence of a base. The diastereoisomeric system (237) has been isolated from the reaction of a cyclic 

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Phosphine Chalcogenides as Ligands. - The complexation of lanthanide and actinide ions by phosphine oxide ligands remains an active area, and a theoretical assessment of the coordination of phosphine oxides (and phosphate esters) by trivalent lanthanide ions has appeared." Trivalent lanthanide complexes of the functionalised enol phosphine oxide (265), (and a related phosphonate), have been describedComplexes of thorium(iv) with bis(di-phenylphosphino) ethane dioxide and bis(diphenylphosphinoyl)amide have also been characterised." Calixarene systems which bear phosphine oxide... 

Phosphine Chalcogenides as Ligands. - The enhanced stability provided by two triphenylphosphine oxide ligands has enabled the first crystal structure analysis of a non-haem-di-iron-dioxygen adduct. Complexes of the bis(phosphine oxide) (213 Z=0) with copper(I) and copper(II), and of the related disulfide (213 Z=S) with gold(I) and silver(I), have been characterised. 

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