Abstract:The title compound, (C27H26P3)[AlCl4]·CH2Cl2, was isolated from a mixture containing the triphosphenium ion and its protonated derivative. The central cation ring is non‐planar, as in the analogous hexachlorostannate (though the structures are not isomorphous), and the P—P distances are intermediate between those typical for single and double bonds.
“…The salt crystallizes in the space group P 2 1 / c , the molecular structure is shown in Figure , and relevant metrical parameters are listed in Table . As observed in 4 [I], the P−P bond distances in 5 [I] are shorter than the typical single bonds and are similar to those observed in the only two other salts containing cations of this type, namely, 5 2 [SnCl 6 ] and 5 [AlCl 4 ]. , The P−P−P angle of 97.77(2)° is wider than the corresponding angle in 4 [I] as one would expect for the six-membered ring produced by the larger and more flexible dppp chelate. 2 Thermal ellipsoid plot (30% probability surface) of 5 [I].…”
An improved method for the synthesis of cyclic low oxidation state P cations is presented. The only byproducts of the reaction of phosphorus triiodide with chelating phosphines are readily removed, resulting in an easily accessible P(I) reagent with an anion that can be readily replaced through salt metathesis chemistry. These P(I) salts are surprisingly stable, even in O2 and moisture, and the origin of this unusual stability is elucidated using density functional theory calculations.
“…The salt crystallizes in the space group P 2 1 / c , the molecular structure is shown in Figure , and relevant metrical parameters are listed in Table . As observed in 4 [I], the P−P bond distances in 5 [I] are shorter than the typical single bonds and are similar to those observed in the only two other salts containing cations of this type, namely, 5 2 [SnCl 6 ] and 5 [AlCl 4 ]. , The P−P−P angle of 97.77(2)° is wider than the corresponding angle in 4 [I] as one would expect for the six-membered ring produced by the larger and more flexible dppp chelate. 2 Thermal ellipsoid plot (30% probability surface) of 5 [I].…”
An improved method for the synthesis of cyclic low oxidation state P cations is presented. The only byproducts of the reaction of phosphorus triiodide with chelating phosphines are readily removed, resulting in an easily accessible P(I) reagent with an anion that can be readily replaced through salt metathesis chemistry. These P(I) salts are surprisingly stable, even in O2 and moisture, and the origin of this unusual stability is elucidated using density functional theory calculations.
“…The compound crystallizes in the space group P 1̅ with half of the molecule present in the asymmetric unit; the complete molecular structure is depicted in Figure . The P–P bond distances (Table ) in macrocycle 6 fall within the ranges of distances (2.113(2)–2.184(2) Å) for cyclic triphosphenium complexes ,,,− reported in the CSD, but the P–P–P angle of 100.82(4)° is considerably larger and is more consistent with those of acyclic triphosphenium cations , The centroid-to-centroid distance between the two cyclopentadiene rings is 3.590 Å, and the interplanar spacing of the rings is 3.195 Å. Thus, it would appear as if the heterocycle should be capable of generating endocyclic sandwich-type complexes.…”
A convenient preparative approach to low-valent phosphorus-rich oligomers is presented. Ligand substitution reactions involving anionic diphosphine ligands of the form [(PR2)2N](-) and [(PPh2)2C5H3](-) and a triphosphenium bromide P(I) precursor result in the formation of phosphorus(I)-containing heterocycles, several of which are of types that have never been prepared before. The methodology described also allows for the preparation of the known heterocycle cyclo-[P(PPh2)N(PPh2)]2 in better yields and purity than the synthetic approach reported previously. Preliminary reactivity studies demonstrate the viability of such zwitterionic oligomers as multidentate ligands for transition metals.
“…Indirect alkylation or arylation involves the treatment of a diphosphane R 2 P(CH 2 ) n PR 2 with a dichlorophosphane R PCl 2 (1 : 1) in the presence of two moles of AlCl 3 , as shown in Scheme 2. 12 We have prepared the complete series of such derivatives in solution for R = Et, n-Pr, i-Pr, t-Bu, c-Hex or Ph with the diphosphanes depe (1) and dppe (6); the 31 P NMR data are listed in Tables 3 and 4 respectively.…”
Section: (B) Indirect Alkylation or Arylationmentioning
confidence: 99%
“…In all of the cyclic triphosphenium ions which have been structurally characterised, the P-P distances lie between 2.1172(7) and 2.135(2) A ˚, attributed to a delocalised system, and a bond order higher than one for both P-P bonds. [1][2][3][4][5][6][7][8][9] This possibility is removed by oxidation, and the bond lengths in the di-ium dications are exactly as expected for single P-P bonds. We predict with some confidence that further structural studies on cyclic triphosphenium ions and on their alkyl-or aryl-substituted derivatives will give comparable results to those obtained in previous studies for the former, and in the present work for the latter, with a likely range between 2.19 and 2.24 A ˚for the single-bonded systems.…”
Section: (B) Indirect Alkylation or Arylationmentioning
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. The crystal and molecular structures of five such derivatives have been ascertained for the first time by single crystal X-ray diffraction at 120 K. The results confirm that normal single P-P bond lengths are present in the dications, in contrast with the monocationic parent cyclic triphosphenium ions, where structural determinations have shown that the P-P bond lengths are intermediate between single and double bonds.
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