Analytically pure chloride and bromide salts of two different cyclic triphosphenium cations are prepared by the reaction of PX3 (X=Cl, Br) in the presence of the halogen-scavenging reagent cyclohexene. For the brominated species, the neutral, volatile 1,2-dibromocyclohexane byproduct is readily removed under reduced pressure, and the desired salts are obtained in high yield. Reactions involving phosphorus trichloride are complicated by the formation of salts containing both chloride and hydrogen dichloride anions. Reactivity experiments on potential undesired halogenated diphosphine byproducts suggest that the formation of such species can be prevented by increasing the concentration of cyclohexene employed in the reaction.
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http://dx.doi.org/10.1021/ic701342u | DOI Listing |
Inorg Chem
September 2012
Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK.
The first transition metal complexes of cyclic triphosphenium ions have been unequivocally identified in solution by (31)P NMR spectroscopy. The ligands coordinate to platinum(II) via the central phosphorus atom, but only when at least one of the outer phosphorus atoms has non-aromatic substituents. Depending on the system, either trans- (the kinetic reaction product) and/or cis- (the thermodynamic reaction product) complexes are formed.
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January 2012
Chemistry Department, University of Durham, South Road, Durham, DH1 3LE, UK.
Reaction of a diphosphane with a chlorophosphane in the presence of SnCl(2) or AlCl(3) leads to the formation of dicationic heterocycles with three (3P) or four (4P) linked phosphorus atoms. Some 3P derivatives with small alkyl substituents may also be prepared by direct alkylation of cyclic triphosphenium ions. Several new species were prepared in solution, some of which were isolated and characterised by single-crystal X-ray diffraction.
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March 2008
Chemistry Department, University of Durham, South Road, Durham, UK DH1 3LE.
Direct alkylation of cyclic triphosphenium ions by triflates to give di-ium dications is only possible for small organic substituents on the attacking reagent. The dicationic products are not intrinsically unstable, however, and in many instances they may be synthesised by an alternative route, pioneered by Schmidpeter and co-workers. These species may be readily identified in solution by (31)P NMR spectroscopy.
View Article and Find Full Text PDFInorg Chem
February 2008
Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, N9B 3P4, Canada.
Analytically pure chloride and bromide salts of two different cyclic triphosphenium cations are prepared by the reaction of PX3 (X=Cl, Br) in the presence of the halogen-scavenging reagent cyclohexene. For the brominated species, the neutral, volatile 1,2-dibromocyclohexane byproduct is readily removed under reduced pressure, and the desired salts are obtained in high yield. Reactions involving phosphorus trichloride are complicated by the formation of salts containing both chloride and hydrogen dichloride anions.
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April 2007
Chemistry Department, University of Durham, South Road, Durham, UK DH1 3LE.
The mechanism of formation of cyclic triphosphenium ions [-(CH(2))(n)P(R(2))PP(R(2))-](+) 3 from diphosphanes R(2)P(CH(2))(n)PR(2) and phosphorus(III) halides PX(3)(X = Cl or Br) has been unequivocally established for the six-membered heterocycles with R = Et, (i)Pr or c-Hex, n= 3, and for five-membered rings with R = Et, n= 2. The initial stage is the formation of an acyclic species, [R(2)P(CH(2))(n)P(R(2))PX(2)](+)X(-) 1. The cation of this species cyclises to a symmetrical dication [-R(2)P(CH(2))(n)P(R(2))P(X)-](2+) 2 by loss of halide, where the middle P atom has an X group attached and is still formally P(iii).
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