Inorg. Chem. 1988, 27, 43504355
4350
Contribution from the Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1
Preparation and Solid-state and Solution Studies of Three Compounds of the Tetraiodine Dication :1': 142+(AsF6-)2,142+(SbF;)2, and 142+(Sb3F14-) (SbFs-) R. Faggiani, R. J. Gillespie,* R. Kapoor, C. J. L. Lock, and J. E. Vekris Received April 5, 1988 Iodine is oxidized by AsFs and SbFS in solution in sulfur dioxide to give I4(ASF6)2 (1) and I4(Sb3FI4)(SbF6)(2), respectively. 14(SbF6)2(3) was prepared by the reaction of 12Sb2Fllwith fluoride ion. Crystals of 1 are monoclinic, space group A 2 / m , with a = 5.876 (2) A, b = 9.810 (4) A, c = 12.41 1 (5) A, fi = 104.06 (4)', V = 694.0 (4) A), and Doak = 4.17 g - ~ mfor - ~Z = 2. Crystals of 2 are also monoclinic, space group PZ,/c, with a = 8.431 (2) A, b = 15.968 (4) A, c = 16.818 (3) A, fi = 100.48 (l)', V = 2226.4 (8) A', and D = 4.10 pcm-' for Z = 4. Crystals of 3 are triclinic, space group Pi,with a = 5.995 (1) A, b = 10.054 (2) A, c = 9.177 (2) (Y = 122.85 (l)', j 3 = 119.08 (l)', y = 90.66 (l)', V = 376.47 (14) A3, and Dale = 4.32 g . ~ m for -~ Z = 1. The structures of 1 and 2 were solved by means of Patterson functions, and that of 3 was solved by direct methods. The three structures were refined by least squares to final agreement indices of R , ( R 2 )= 0.050 (0.059), 0.058 (0.062), and 0.066 (0.083) for 812, 3550, and 1316 independent reflections, respectively. 1 and 3 consist of discrete 142+ and ASFs-and SbF6- ions, respectively, and 2 consists of 14*+, Sb3F14-,and SbF6- ions. The IC+ cation in all three compounds has a rectangular structure and may be considered to consist of two 12+ cations joined by two long weak bonds. Resonance Raman spectra were obtained from the solid compounds. The spectra had a single line at 232 cm-I together with several overtones. In solution in SO2and HS03F at room temperature, the IC+ ion is dissociated to 12+, but at -78 OC in HS03F and SO2, 142+ is the predominant species.
1,
T h e iodine cations 12+,13+, Is+, and IIs3+have been prepared and characterized in solution in highly acidic media such as HS03Fand H2SO4, and several crystalline salts of these ions have been isolated.'V2 The structures of 12+(Sb2FlI-), 13+(AsF6-), Is+(AsF6-), and IIs3+(SbF6-) have been determined by X-ray ~rystallography.~" In one of the early studies3 on the cation 12+ it was observed that, on cooling of a solution of the cation in HS03F, the color of the solution changed from an intense blue to a deep red-brown at about -80 O C and at the same time the paramagnetism of the solution decreased considerably.6 These results were explained by assuming that a t low temperatures paramagnetic 12+dimerizes to the diamagnetic Id2+ion. Cryoscopic and conductometric measurements on solutions of 12+(S03F)in fluorosulfuric acid were also consistent with the formation of 142+a t -78 O C 6 No information on the structure of this species was obtained a t that time, however. W e have now found that I:+(ASF~-)~ and I:+(SbF;)(Sb3F1c) can be obtained as products of the room-temperature reactions of I2 with AsFs and SbFs in solution in SO2,respectively, and that the compound 14+(SbF6-)2can be obtained by the room-temperature reaction of 12(Sb2FII-) with fluoride ion. This paper reports the preparation of these solid crystalline compounds and their characterization by means of Raman spectroscopy and X-ray crystallography. T h e formation of the 142+ ion in solution and the equilibrium with 12+have also been further studied. A preliminary report of the X-ray crystal structures of 1 and 2 has k e n published previously.'
Experimental Section Materials and General Procedures. Antimony pentafluoride (OzarkMahoning Co.) was purified by double distillation in an all-glass apparatus under a dry N2 atmosphere and stored in FEP bottles with Kel-F stoppers in a drybox. Arsenic pentafluoride was prepared by the direct fluorination of freshly sublimed arsenic in a nickel can at liquid-N2 temperature. Iodine (BDH Analytical reagent) was further purified by sublimination. Sulfur dioxide (Canadian Liquid Air Ltd.) was distilled
from and kept over phosphoric oxide before use. Reactions were carried out in a two-bulb glass vessel incorporating a medium sintered-glass frit, a Rotoflow valve, and a Teflon-covered stirring bar. A drybox equipped with a microscope was used to select suitable crystals for X-ray structural determination. These crystals were sealed in Lindemann capillaries (0.24.3-mm diameter) under a dry nitrogen atmosphere. Raman spectra were recorded with a Spex Industries Model 1400 spectrometer equipped with a double monochromator, an RCA C31034 phototube detector, an electrometer amplifier, and a recorder. The exciting radiation was either the red 6328-A line of a Spectra-Physics 125 He-Ne laser or the green 5145-A line of a Spectra-Physics Model 140 Ar+ laser. Both solid and liquid samples were sealed in 0.25-in.-0.d. Pyrex tubes. These were spun, when it was appropriate, to minimize decomposition. Low-temperature spectra were recorded by mounting the sample in a double-walled Pyrex glass Dewar flask. Liquid nitrogen was boiled off from a Dewar flask at a controlled rate by an electric heater and the cold gas passed through the sample Dewar flask. The temperature was monitored with a copper-onstantan thermocouple positioned just upstream of the sample. The infrared spectrum of 14(A~F6)Z was recorded on a Perkin-Elmer Type 283 grating infrared spectrometer (4000-200 cm-I) in a KBr pellet. Magnetic Susceptibility. Magnetic susceptibility measurements were carried out on a fully automated Faraday magnetic balance* calibrated with Hg[Co(NCS),]. Temperatures were measured with a National Research Council thermocouple. A diamagnetic correction was determined for the sample container. Other diamagnetic corrections (cm3mol-I) used were as follows: F,0.3 X lo6; Sb(V), -14.0 X lo6;I-, -44.6 x 106.9 UV-Visible Absorption Spectrascopy. Solution spectra were recorded (220-750 nm) on a Cary 14 spectrometer. Solutions in SO2were prepared in an apparatus composed of a 1.0-cm rectangular silica cell (Helma) with a graded seal to a Rotoflow valve and a Pyrex vessel equipped with a magnetic stirrer. Lower temperature spectra were taken in a quartz Dewar flask with quartz windows. The Dewar flask was cooled by passing cold N2 from a liquid-nitrogen boiler, and the temperature was measured with a thermocouple. Reparatiom. (a) I ~ ~ + ( A S FIodine ~ ) ~ . (10 mmol, 2.54 g) was allowed to react with AsFS (15 mmol, 2.55 g) in solution in SO2 at room temperature. 212 + 3AsFS 142+(ASF6-)2+ AsF3 The dark green solution was stirred for 48 h, after which the volatile components of the reaction were slowly removed, producing dark crystals. These crystals gave a red powder on grinding. The same reaction was carried out in solution in S02CIFand gave an immediate precipitate of a red amorphous powder. This powder was dissolved in SO2,and crystalline material was obtained from this solution by slow removal of the solvent. Crystals from both preparations were shown, by an X-ray crystallographic study, to be the compound 14(ASF6)2, 4
Gillespie, R. J.; Passmore, J. In Advances in Inorganic Chemistry and Radiochemistry; Emeleus, H. J., Sharpe, A. J., Eds., Academic: New York, 1975; Vol. 17, pp 49-87 and references therein. Passmore, J.; Taylor, P.; Whidden, T.; White, P. S. Can. J. Chem. 1979, 57, 968-973. Davies, C. G.; Gillespie, R. J.; Ireland, P. R.; Sowa, J. M. Can. J . Chem. 1974, 52, 2048-2052. Passmore, J.; Sutherland, G.; White, P. S. Inorg. Chem. 1981, 20, 2169-2171. Apblett, A.; Grein, F.; Johnson, J. P.; Passmore, J.; White, P. S. Inorg. Chem. 1986, 25, 422-426. Gillespie, R. J.; Milne, J. B.; Morton, M. J. Inorg. Chem. 1968, 7, 2221-2225. Gillespie, R. J.; Kapoor, R.; Faggiani, R.; Lock, C. J. L.; Murchie, M.; Passmore, J. J. Chem. SOC.,Chem. Commun. 1983, 8-9.
(8) Donini, J. C.; Hollebone, B. R.; Kochlet, R. A,; Lever, A. B. P. J. Phys. E 1972, 5, 385.
(9) Figgis, B. N.; Lewis, J. In Modern Coordination Chemistry; Lewis, J., Wilkins, R. G., Eds.; Interscience: New York, 1960.
0020-1669/88/1327-435O$OlSO/O 0 1988 American Chemical Society
Table I. Summary of the Structure Determinations fw cryst size, mm syst absences space group unit cell consts: A, deg
v,A' Z
wm-' temp, OC abs coeff p, cm-l (pcalcfrom SHELX, cm-I) max 20, deg octants
PCaIC'
std reflcns (esd) no. of reflcns collcd Rmcrg
no. of indep reflcns no. of reflcns with I > 0 used final residuals: R I f R2c final shift/error: max; av. final diff map peaks, e.A-': max; min secondary extinctn x weighting function error in observn of unit wt
14(ASF6)2 885.438 0.2 X 0.17 X 0.33 hkl, k + I = 2n + 1
14(SbF6)2 979.094 0.2 X 0.27 X 0.33
14(Sb,F14) (SbF6) 1374.578 0.06 X 0.10 X 0.33 hOl, I = 2n + 1; OkO, k = 2n + 1 P2dC a = 8.431 (2), b = 15.968 (4), c = 16.818 (3); j3 = 100.48 (1)
A2/ma a = 5.876 (2), b = 9.810 (4), c = 12.411 (5); j3 = 104.06 (4)
Pi a = 5.995 (l), b = 10.054 (2), c = 9.177 (2); a = 122.85 (l), @ = 119.08 (l), y = 90.66 (1)
694.0 (4) 2 4.2 -35 140.8 (131.2)
376.4 (1) 1 4.3 22 119.9 (113.9)
2226.4 (8) 4 4.1 22 106.3 (101.6)
55 0 Q h Q 7,O Q k Q 12, -15 6 I d 15 302 (0.013); 133 (0.013) 94 1 0.038 812 811 0.052; 0.059 0.001;
