Hexafluorophosphate anion

Hexafluorophosphates. There is a great deal of interest in the hexafluorophosphate anion [1691-18-8], mostly as organic hexafluorophosphates for catalysis in photopolymerization. A number of the compounds are diazonium compounds (see Photoreactivepolymers). 

To obtain the pure topological enantiomers, the chiral auxiliary was easily replaced by the hexafluorophosphate anion. 

Phosphenium ions can also be stabilized by intramolecular coordination to a Lewis base. In ion 294, which was prepared by hydride abstraction739 [Eq. (4.177)], intramolecular bis-coordination exists. The31P NMR spectrum of the corresponding P—H derivative740 exhibits one doublet at 831P 37.6 (JP N = 243 Hz). The X-ray structure, which shows no interaction between the cation and the hexafluorophosphate anion, clearly demonstrates an ionic structure. Both arms are coordinated to the phosphorus center. The N—P distances are 2.082 and 2.068 A, which are longer than the N—P o-bond (1.769 A) but significantly shorter than the sum of the two van der... 

Figure 1-1. The formation of co-ordination compounds may involve only main group donors and acceptors, as shown in the formation of the adduct between trimethylamine and boron trifluoride, and in the formation of the hexafluorophosphate anion.

Fig. 25 A portion of the structure of crystalline [AuI C(NHMe)2 2](PF6)-0-5(acetone), which emphasizes aurophilic interactions and the hydrogen bonding interactions between two cations and a hexafluorophosphate anion. The Au--- Au distance is 3.1882(1) A. From [48]...

Binding of a complex anionic species with the help of hybrid macrocycles able to provide different interactions with the anion simultaneously was demonstrated in an elegant manner by Stoddart et al. They reported the organization of macrocyde via the anion-assisted assembly of large [5]- and [6]pseudorotaxanes from dibenzy-lammonium threads and polyether macrocydes. The resulting systems were found to be interwoven around a central hexafluorophosphate anion (Scheme 9.12, structure 59) [117]. 

In another approach, it was demonstrated by X-ray diffraction that the optically pure, tertiary phosphine ligand (5,5)-(-i-)-Ph2PCH2CH2P(Ph)CH2CH2P(Ph)CH2CH2-PPh2 yields a left-handed double-helical complex of di-silver(I) as well as a corresponding side-by-side conformer. A molecule of each species is found (together with their associated hexafluorophosphate anions) in each unit cell. 

The synthesis of the simple dinuclear racks 42-45, incorporating two bis-terpyridine ruthenium(II) co-ordination spheres, has been achieved by reaction of 2.5 equivalents of [Ru(2,2 6, 2 -terpyridine)Cl3] with the appropriate bis-tridentate species, followed by addition of hexafluorophosphate anion. X-Ray diffraction studies have allowed elucidation of the effect of the central R group on the overall shape of the respective molecular racks. Thus, when R = Me (43) there is a straightening of the structure relative to the presence of more bulky alkyl substituents. It... 

Fig. 1 Diagrams depicting a a layer of a cubic sodium chloride crystal b a monoclinic 1,3-dimethylimidazolium chloride ionic-liquid crystal c two radial distribution functions (RDFs) in liquid l-dodecyl-3-methylimidazolium hexafluorophosphate. Anions and cations are depicted in red and blue. In the cases of b and c the blue circles represent the centroid of the imidazolium rings of the cations. The alternating sequences of red and blue circles in a and b as well as the two curves in phase opposition in c clearly indicate the existence and nature of the polar networks in ionic condensed phases...

Scovazzo P, Kiel J, Finan DA, Koval C, DuBois D, Noble R (2(X)4) Gas separations using non-hexafluorophosphate anion supported ionic liquid membranes. J Membr Sci 238 57-63... 

Fig. 4.1-4 Probability distribution of (a) chloride from liquid [MMIM]Cl at 150°C, (b) hexafluorophosphate anion and (c) the 1,3-dimethyl imidazolium cation from liquid [MMIM][PF6] at 127 °C around a central imidazolium cation, as determined by the EPSR model ofthe neutron diffraction data.

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