TRISPHAT (full name tris(tetrachlorocatecholato)phosphate(1−)) is an inorganic anion with the formula P(O
2C
6Cl
4)−
3 often prepared as the tributylammonium ((C
4H
9)
3NH+
) or tetrabutylammonium ((C
4H
9)
4N+
salt. The anion features phosphorus(V) bonded to three tetrachlorocatecholate (C
6Cl
4O2−
2) ligands. This anion can be resolved into the axially chiral enantiomers, which are optically stable (the picture shows the Δ enantiomer).
The TRISPHAT anion has been used as a chiral shift reagent for cations.[1] It improves the resolution of 1H NMR spectra by forming diastereomeric ion pairs.
Preparation
The anion is prepared by treatment of phosphorus pentachloride with tetrachlorocatechol followed by a tertiary amine gives the anion:
- PCl5 + 3 C6Cl4(OH)2 → H[P(O2C6Cl4)3] + 5 HCl
- H[P(O2C6Cl4)3] + Bu3N → Bu3NH+ [P(O2C6Cl4)3]−
Using a chiral amine, the anion can be readily resolved.[2]
References
- ^ Ratni, Hassen; Jodry, Jonathan J.; Lacour, Jérôme; Kündig, E. Peter (2000). “[n-Bu4N][Δ-TRISPHAT] Salt, an Efficient NMR Chiral Shift Reagent for Neutral Planar Chiral Tricarbonylchromium Complexes”. Organometallics. 19 (19): 3997–3999. doi:10.1021/om000437f.
- ^ Favarger, France; Goujon-Ginglinger, Catherine; Monchaud, David; Lacour, Jérôme (2004). “Large-Scale Synthesis and Resolution of TRISPHAT [Tris(tetrachlorobenzenediolato) Phosphate(V)] Anion”. Journal of Organic Chemistry. 69 (24): 8521–8524. doi:10.1021/jo048641q. PMID 15549835.