Dl. Zhang et al., A F-19 nuclear magnetic resonance study of the conjugate Bronsted-Lewis superacid HSO3F-SbF5. Part 1, CAN J CHEM, 77(11), 1999, pp. 1869-1886
Citations number
32
Categorie Soggetti
Chemistry
Journal title
CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE
The Bronsted-Lewis superacid HSO3F-SbF5 or "magic acid" is re-investigated
by modern F-19 NMR methods over a wide concentration range. The system is f
ound to be considerably more complex than had been assumed previously. A,to
tal of 13 different anions are identified of which only five have previousl
y been identified in magic acid. With increasing SbF5 contents the concentr
ation of monomeric anions like [SbF6](-), [SbF5(SO3F)](-), cis- and trans-[
SbF4(SO3F)(2)](-), and mer-[SbF3(SO3F)(3)](-) gradually decreases. Except f
or [Sb2F11](-), which is present in very small concentrations only the form
ation of oligomers involves exclusively mu-fluorosulfato bridges. In additi
on to donor (SO3F)(-) and acceptor (SbF5) complex formation to give [SbF5(S
O3F)](-) and possibly ligand redistribution, the solvolysis of SbF5 or SbF4
(SO3F) in HSO3F appears to be the principal formation reaction for polyfluo
rosulfatofluoroantimonate(V) anions. In glass (NMR tubes) the solvolysis pr
oduct HF is converted to the oxonium ion [H3O](+), which has previously bee
n identified by H-1 NMR and structurally characterized as [H3O][Sb2F11] by
us.