2822 Inorganic Chemistry, Vol. 39, No. 13, 2000
Gerken et al.
been characterized for the first time in solution by 75As NMR
spectroscopy. While [AsCl4][As(OTeF5)6] is stable, [AsBr4][As-
(OTeF5)6] undergoes slow decomposition at room temperature
ClOTeF5 (1.7750 g, 9.104 mmol; 5.3 mol % excess) was condensed at
-196 °C into a preweighed 100 mL Pyrex glass bulb equipped with a
J. Young stopcock, followed by condensation of Br2 (0.6905 g, 4.321
mmol) into the bulb at -196 °C. The mixture was allowed to react at
room temperature in the dark for 12 h, forming an orange-brown vapor
over a dark-red liquid. The reaction vessel was connected to a series
of two dry glass U-traps, and the vessel was cooled to -20 °C. The
contents were slowly pumped through traps cooled to -45 and -78
°C, respectively, to remove excess ClOTeF5. A ruby-red liquid was
collected at -45 °C, whereas an orange solid was collected at -78
°C. The -45 °C trap was warmed to room temperature, and all the
material was distilled into the -78 °C trap. The cold baths were then
exchanged and the product pumped in the opposite direction over a
period of 90 min, collecting the product in the -45 °C trap. The final
product was a deep-ruby-red liquid; yield 2.7375 g (8.595 mmol, 99.5%
based on the total amount of Br2), mp -52 °C (reported value -75
°C).72 The 19F NMR spectrum of the product in SO2ClF solvent at -50.3
°C showed a single AB4 pattern (FA, -47.2 ppm; FB, -53.9 ppm;
2J(19FA-19FB), 180 Hz; 1J(125Te-19FA), 3419 Hz; 1J(125Te-19FB), 3788
Hz) and no detectable impurities.
Syntheses of [AsCl4][As(OTeF5)6], [AsBr4][As(OTeF5)6], [AsBr4]-
[AsF(OTeF5)5], and [AsCl4][Sb(OTeF5)6-nCln]. (a) [AsCl4][As-
(OTeF5)6]. In the drybox As(OTeF5)5 (1.0573 g, 0.8339 mmol) was
loaded into a 7 mm glass tube equipped with a 4 mm J. Young stopcock.
On the vacuum line, 0.1576 g (0.8693 mmol) of AsCl3 and 0.2909 g
(1.0615 mmol) of ClOTeF5 were distilled into the tube at -196 °C
and the mixture was allowed to warm to and remain at room temperature
overnight. Excess ClOTeF5 was removed by pumping first at -78 °C
and then at room temperature to give a white powder. The product
was returned to the drybox and loaded into a two-arm glass crystal-
lization vessel where it was recrystallized from SO2ClF. To obtain
crystals suitable for X-ray crystallography, the solution was cooled from
45 °C to room temperature over several days in a water bath.
Transparent, well-defined, hexagonal crystals appeared and were
isolated by sealing off one arm of the reactor.
-
but is kinetically more stable than the previously reported AsF6
salt and the presently reported AsF(OTeF5)5- salt, which rapidly
decompose upon warming to room temperature. Analysis of the
bond valence parameters associated with the long cation-anion
-
contacts reveals that the As(OTeF5)6 anion is more weakly
+
coordinating toward AsCl4 than AsF6-. Density functional
theory calculations have been used to calculate the geometrical
parameters and vibrational frequencies of known PnX4+ cations
and have been used to predict those of the presently unknown
+
BiX4+, SbF4+, and SbI4 cations.
Experimental Section
Materials and Apparatus. Manipulations involving volatile materi-
als were performed under strictly anhydrous conditions as described
previously.30 Caution: Most of the compounds described in this work
are highly toxic and must be handled on vacuum systems or in dryboxes
that have pumps and ports that are correctly vented and in laboratories
equipped with adequate ventilation and fume hoods. In addition, work
involving the handling of glass vessels pressurized with SO2ClF and
liquid Cl2 should be conducted with proper shielding in place.
Sulfurylchlorofluoride, SO2ClF (Columbia Organic Chemical Co.),
was purified according to the literature method.68 Chlorine gas
(Matheson) was dried by bubbling through concentrated sulfuric acid
followed by condensation at -78 °C into a dry glass U-tube equipped
with J. Young glass/Teflon stopcocks and stored at -78 °C until it
was used. Arsenic tribromide (Strem Chemical, 99.9%) was used
without further purification. Arsenic trichloride, AsCl3 (BDH, >99%)
and SbCl5 (Eastman Kodak) were vacuum-distilled twice and stored
in Pyrex glass vessels prior to use. Literature methods were used to
prepare ClOTeF5,69 B(OTeF5)3,53 As(OTeF5)5,70 and AgOTeF5.50,71
Preparation of AsF(OTeF5)4. It was not possible to obtain AsF-
(OTeF5)4 completely free of As(OTeF5)5. The preparation was similar
to that used to prepare As(OTeF5)5,70 which has been previously
obtained in high purity. In a typical preparation, 1.3275 g (7.81 mmol)
of AsF5 was condensed onto 9.4889 g (13.05 mmol) of B(OTeF5)3 at
-196 °C contained in one bulb of a dry double-bulb (100 mL each)
glass reaction vessel equipped with a magnetic stirring bar, with a J.
Young stopcock on one side and a medium porosity glass frit separating
the two bulbs. The vessel and contents were allowed to warm to room
temperature, whereupon the mixture liquified and BF3 evolution took
place. The mixture was allowed to stand for 24 h prior to condensing
ca. 20 mL of SO2 onto the reaction mixture, which was stirred for a
further 48 h. Purification by recrystallization from liquid SO2 was
identical to that previously reported for As(OTeF5)5. The melting point
of the product ranged from 25 to 30 °C. The 19F NMR spectrum at
-70 °C consisted of a well-resolved AB4 spin coupling pattern (FA,
(b) [AsBr4][As(OTeF5)6] and [AsBr4][AsF(OTeF5)5]. In the drybox,
AsF(OTeF5)4 containing ca. 5-10 mol % As(OTeF5)5 (0.8021 g) was
1
transferred in a two arm /4 in. o.d. FEP tube. The tube was cooled to
below -100 °C, and AsBr3 (0.2016 g, 0.6407 mmol) was added. The
cold tube was removed from the drybox and maintained at -78 °C
until SO2ClF (ca. 3 mL) was distilled into the tube. The BrOTeF5 was
distilled into a preweighed graduated glass tube, and 0.2111 g (0.6628
mmol) was distilled from there into the reaction tube. The sample was
warmed briefly to 0 °C and mixed, and about 0.5 mL of SO2ClF was
rapidly pumped off. Crystals were grown at -30 °C, slowly decreasing
the temperature to -38 °C over a period of 8 h. During this period
large well-formed tablet-shaped crystals were deposited on the walls.
The sample was cooled to -45 °C, and the solvent was decanted into
the sidearm. The sidearm was then cooled with liquid N2 and heat-
sealed off under vacuum. Samples for Raman and 19F NMR spectro-
scopic studies were prepared in a similar manner by mixing the reagents
at -78 °C in SO2ClF and rapidly pumping to dryness at 0 °C. The
resulting pale-yellow powder was transferred at low temperature (ca.
-100 to -120 °C) inside a drybox into the appropriate glass sample
tubes, which were closed and removed from the drybox. In the case of
the NMR samples, SO2ClF solvent was condensed into the sample tubes
at -196 °C and all tubes were heat-sealed at -196 °C. Samples for
75As NMR spectroscopy were prepared directly from the reagents
BrOTeF5 and AsF(OTeF5)4, as described above, in 10 mm thin-wall
glass NMR tubes and heat-sealed with SO2ClF solvent. All samples
were stored at -78 °C or lower until their spectra or crystal structure
could be determined.
2
1
-48.6 ppm; FB, -39.8 ppm; J(19FA-19FB), 182 Hz; J(125Te-19FA),
3643 Hz; J(125Te-19FB), 3722 Hz) that is very similar to that of As-
1
(OTeF5)5 except that a broadened singlet (12.6 ppm; ∆ν1/2 ) 125 Hz)
corresponding to fluorine directly bonded to arsenic also appears. The
relative integrated intensities of the F-on-Te region (inclusive of 125Te
and 123Te satellites) to the F-on-As region was 20:1. The singlet was
presumably broadened by the unresolved four-bond scalar couplings
to the axial and equatorial fluorines on tellurium and/or by the nearly
quadrupole collapsed 1J(75As-19F) coupling. The observation of a single
AB4 pattern at low temperature is consistent with a trigonal pyramidal
arrangement of F and OTeF5 ligands undergoing rapid intramolecular
exchange by means of a Berry-style pseudorotation mechanism.
Preparation of High-Purity BrOTeF5. The synthesis of BrOTeF5
is an improved version of the published method.72 In a typical synthesis,
(c) [AsCl4][Sb(OTeF5)6-nCln]. The procedure for the preparation
of AgSb(OTeF5)6 was similar to that reported previously except that
the reaction was carried out in SO2ClF solvent. The reagents SbCl5
(0.5098 g, 1.705 mmol) and AgOTeF5 (5.5612 g, 10.28 mmol) were
transferred into the central arm and into one of the sidearms of a three-
arm glass reaction vessel, which was equipped with three 4 mm J.
Young stopcocks and two medium porosity glass frits separating the
(68) Schrobilgen, G. J.; Holloway, J. H.; Granger, P.; Brevard, C. Inorg.
Chem. 1978, 17, 980.
(69) Seppelt, K.; Turowsky, L. Z. Anorg. Allg. Chem. 1990, 590, 37.
(70) Collins, M. J.; Schrobilgen, G. J. Inorg. Chem. 1985, 24, 2608.
(71) Strauss, S. H.; Noirot, M. O.; Anderson, O. P. Inorg. Chem. 1985,
24, 4307.
(72) Seppelt, K. Chem. Ber. 1973, 106, 1920.
Gerken, Michael
