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The chemistry of cationic polyphosphorus cages--syntheses, structure and reactivity.

Holthausen MH, Weigand JJ - Chem Soc Rev (2014)

Bottom Line: The aim of this review is to provide a comprehensive view of the chemistry of cationic polyphosphorus cages.The synthetic protocols established for their preparation, which are all based on the functionalization of P4, and their intriguing follow-up chemistry are highlighted.In addition, this review intends to foster the interest of the inorganic, organic, catalytic and material oriented chemical communities in the versatile field of polyphosphorus cage compounds.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Toronto, Toronto, Canada. m.holthausen@utoronto.ca.

ABSTRACT
The aim of this review is to provide a comprehensive view of the chemistry of cationic polyphosphorus cages. The synthetic protocols established for their preparation, which are all based on the functionalization of P4, and their intriguing follow-up chemistry are highlighted. In addition, this review intends to foster the interest of the inorganic, organic, catalytic and material oriented chemical communities in the versatile field of polyphosphorus cage compounds. In the long term, this is envisioned to contribute to the development of new synthetic procedures for the functionalization of P4 and its transformation into (organo-)phosphorus compounds and materials of added value.

No MeSH data available.


Related in: MedlinePlus

Nortricyclane type molecular structures of the related, polyphosphorus cations 59f+, 612+ and 433+.
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fig12: Nortricyclane type molecular structures of the related, polyphosphorus cations 59f+, 612+ and 433+.

Mentions: Their structural motif resembles that of nortricyclane, with a basal P3-ring, the tetra-coordinated P atom and the selenium atoms occupying the bridging positions, and one P atom defining the apex of the cage. This class of compounds feature interesting 31P and 77Se NMR characteristics. Cages 59a,f+ reveal an AM2OX spin system for the CS-symmetric isotopomer without a 77Se nucleus. These resonances are superimposed by the C1-symmetric isotopomer featuring one 77Se atom in one of the bridging positions. This isotopomer gives rise to an AMNOXZ spin system which is highly influenced by higher order effects. However, in the case of 59a+, the spin systems of both isotopomers were successfully simulated allowing for the exact determination of chemical shifts and coupling constants. A series of experiments employing varying temperatures, reaction times and stoichiometries gave meaningful insights into the mechanism of the chalcogenation. These experiments indicate that the insertion of Se atoms into P–P bonds of 36a,f+ proceeds in a stepwise manner via the intermediates 60a,f+. In the case of alkyl-substituted cage 36a+ the insertion of a second equivalent grey selenium is fast, yielding the respective product 59a+ quantitatively. If the aryl-substituted starting material 36f+ is employed, the intermediate formation of dication 612+ is observed. This species forms via the transfer of a [Ph2P]+ moiety from a second equivalent of 36f+ to the reactive intermediate 60f+. Due to the higher stability of the corresponding phosphenium ion Ph2P+,19,50 this transfer is faster than the insertion of the second selenium atom. Subsequently, one of the [Ph2P]+-moieties of 612+ is substituted by a selenium atom giving rise to 59f+. The formally liberated Ph2P+-phosphenium ion is not stable and reacts with a GaCl4– anion to give the Lewis acid–base adduct 37 (Ph2PCl–GaCl3). This is in accordance with the observation of only 50% conversion and the quantitative formation of P4 and 37 or the respective oxidation product Ph2P(Se)Cl–GaCl3 in the case of reactions involving 36f+ as a starting material. The targeted preparation of 612+ as GaCl4– salt is achieved by utilizing a 2 : 1 stoichiometry of 36f+ and grey selenium. Another synthetic approach for the preparation of 612+ is the targeted substitution of one [Ph2P]+-moiety in the tricationic cage 433+. This is achieved by reacting 433+ with grey selenium under solvent-free conditions (Scheme 17).49 Dication 612+ was comprehensively characterized by X-ray crystallography (Fig. 12) as well as 31P and 77Se NMR spectroscopy. The 31P NMR spectrum reveals a characteristic AA′MOXX′-spin system for the isotopomer without a 77Se nucleus which is superimposed by the respective AA′MOXX′Z-spin system of the 77Se containing species.


The chemistry of cationic polyphosphorus cages--syntheses, structure and reactivity.

Holthausen MH, Weigand JJ - Chem Soc Rev (2014)

Nortricyclane type molecular structures of the related, polyphosphorus cations 59f+, 612+ and 433+.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4288811&req=5

fig12: Nortricyclane type molecular structures of the related, polyphosphorus cations 59f+, 612+ and 433+.
Mentions: Their structural motif resembles that of nortricyclane, with a basal P3-ring, the tetra-coordinated P atom and the selenium atoms occupying the bridging positions, and one P atom defining the apex of the cage. This class of compounds feature interesting 31P and 77Se NMR characteristics. Cages 59a,f+ reveal an AM2OX spin system for the CS-symmetric isotopomer without a 77Se nucleus. These resonances are superimposed by the C1-symmetric isotopomer featuring one 77Se atom in one of the bridging positions. This isotopomer gives rise to an AMNOXZ spin system which is highly influenced by higher order effects. However, in the case of 59a+, the spin systems of both isotopomers were successfully simulated allowing for the exact determination of chemical shifts and coupling constants. A series of experiments employing varying temperatures, reaction times and stoichiometries gave meaningful insights into the mechanism of the chalcogenation. These experiments indicate that the insertion of Se atoms into P–P bonds of 36a,f+ proceeds in a stepwise manner via the intermediates 60a,f+. In the case of alkyl-substituted cage 36a+ the insertion of a second equivalent grey selenium is fast, yielding the respective product 59a+ quantitatively. If the aryl-substituted starting material 36f+ is employed, the intermediate formation of dication 612+ is observed. This species forms via the transfer of a [Ph2P]+ moiety from a second equivalent of 36f+ to the reactive intermediate 60f+. Due to the higher stability of the corresponding phosphenium ion Ph2P+,19,50 this transfer is faster than the insertion of the second selenium atom. Subsequently, one of the [Ph2P]+-moieties of 612+ is substituted by a selenium atom giving rise to 59f+. The formally liberated Ph2P+-phosphenium ion is not stable and reacts with a GaCl4– anion to give the Lewis acid–base adduct 37 (Ph2PCl–GaCl3). This is in accordance with the observation of only 50% conversion and the quantitative formation of P4 and 37 or the respective oxidation product Ph2P(Se)Cl–GaCl3 in the case of reactions involving 36f+ as a starting material. The targeted preparation of 612+ as GaCl4– salt is achieved by utilizing a 2 : 1 stoichiometry of 36f+ and grey selenium. Another synthetic approach for the preparation of 612+ is the targeted substitution of one [Ph2P]+-moiety in the tricationic cage 433+. This is achieved by reacting 433+ with grey selenium under solvent-free conditions (Scheme 17).49 Dication 612+ was comprehensively characterized by X-ray crystallography (Fig. 12) as well as 31P and 77Se NMR spectroscopy. The 31P NMR spectrum reveals a characteristic AA′MOXX′-spin system for the isotopomer without a 77Se nucleus which is superimposed by the respective AA′MOXX′Z-spin system of the 77Se containing species.

Bottom Line: The aim of this review is to provide a comprehensive view of the chemistry of cationic polyphosphorus cages.The synthetic protocols established for their preparation, which are all based on the functionalization of P4, and their intriguing follow-up chemistry are highlighted.In addition, this review intends to foster the interest of the inorganic, organic, catalytic and material oriented chemical communities in the versatile field of polyphosphorus cage compounds.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Toronto, Toronto, Canada. m.holthausen@utoronto.ca.

ABSTRACT
The aim of this review is to provide a comprehensive view of the chemistry of cationic polyphosphorus cages. The synthetic protocols established for their preparation, which are all based on the functionalization of P4, and their intriguing follow-up chemistry are highlighted. In addition, this review intends to foster the interest of the inorganic, organic, catalytic and material oriented chemical communities in the versatile field of polyphosphorus cage compounds. In the long term, this is envisioned to contribute to the development of new synthetic procedures for the functionalization of P4 and its transformation into (organo-)phosphorus compounds and materials of added value.

No MeSH data available.


Related in: MedlinePlus