1454 zyxwvutsrqpon Inorganic Chemistry, Vol. zyxwvut 15, No. 6, zyxwvuts 1976 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA of Br(S03F)34 with the highest SO stretch at 1490 cm-'. From a comparison of the Raman spectra listed in Table I1 it appears that the bands in the region of 640-750 cm-' are not found for the potassium salt and are most likely due to the [Hal(S03F)21f ion. Since both SO3F stretching and deformation modes are generally not found in this region and are rarely so intense, assignment of these bands as halo- gen-oxygen skeletal vibrations is plausible. The following assignment is suggested: v(BrO*),, at 745 cm-I and v(BrO& at 652 and 640 cm-I; ~(102)as at 712 and 690 cm-' and ~ ( 1 0 2 ) ~ at 663 and 650 cm-I. The observed splittings of some of the modes may be due to a slight nonequivalence of the two [Hal(SO3F)2]+ ions in the cation. A band at 309 cm-' for the bromine compound and at 284 cm-I for the iodine compounds may be the BrO2 or the I02 bending mode, re- spectively. These assignments of the Br-0 and 1-0 skeletal vibrations suggest that our previous4 assignments of these vibrations in I(S03F)3and Br(S03F)3 are probably too low and should be revised. All bands in the lower frequency range are not distin- guishable from the anion vibrations, perhaps with the exception of the bending mode at -625 cm-' which is also present in [I(SO3F)4]-. The Raman bands at 308, 462, and 1242 cm-' reported by Gillespie and Morton7 for solutions of Br(S03F)3 in superacid and ascribed to the [Br(S03F)2lf cation are all observed as strong bands for solid [Br(so3F)2]2[sn(so,F)6] in approximately the same region. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Experimental Section The chemicals S206F2,12 S II(SO~F)~,~S~~ I(S03F)3,1 and BrS03F3 were synthesized according to published methods. Raman spectra were obtained on a Cary 8 1 spectrometer equipped with a Spectra Physics Model 125 He-Ne Laser. The samples were contained in flat-bottom Pyrex tubes (5-mm 0.d.) Solids were handled in a "Dri-Lab", Model No. HE-re-2 (Vacuum Atmospheric Corp.), filled with purified dry nitrogen and equipped with a "Dri-Train", Model No. HE-93 B. The Mossbauer spectrometer has been described el~ewhere.~ All synthetic reactions were carried out in Pyrex reactors of zyxwvuts N 100-ml volume, equipped with Teflon stem valves and Teflon-coated magnetic stirring bars. Generally 10-20 ml of S206F2 was added to the reaction mixture by vacuum distillation. Details of the synthesis are given in the Discussion. The solid materials were obtained after removal of the solvent. In the case of [I(SO3F)2]2[Sn(SO3F)6] a yellowish liquid mass was formed initially which solidified only after 3-5 days. Characterization of the Compounds. [I(so3F)2]2[sn(so3F)6] is a yellowish white, very hygroscopic solid (mp 74-75 "C). Quantitative analysis was performed by Alfred Bernhardt, Elbach, West Germany. Anal. Calcd: I, 18.63; S, 23.49; F, 13.87. Found: I, 18.77; S, 23.53; F, 14.23. [Br(SO3F)2]~Sn(SO3F)6] is a pale yellow to white, very hygroscopic solid, melting to a yellow liquid at 48-50 OC. Anal. Calcd: Br, 12.60; S, 25.22; F, 14.90. Found: Br, 12.86; S, 25.47; F, 15.15. Acknowledgment. Financial support from the National Research Council of Canada is gratefully acknowledged. Registry No. zyxwvutsrqpo [ I(S03F)2]2[sn(so,F),], 587 18-63- 1; [Br(S03- F)2]2[Sn(SO3F)6], 58718-64-2; Sn(S03F)c2BrSO3F, 587 18-65-3; I(SO3F)3, 13709-37-0; Sn(S03F)4, 28017-03-0. References and Notes (1) J. R. Roberts and G. H. Cady, J. Am. Chem. SOC., 82, 354 (1960). (2) F. Aubke and G. H. Cady, Inorg. Chem., 4, 269 (1965). (3) F. Aubke and R. J. Gillespie, Inorg. Chem., 7, 599 (1968). (4) H. A. Carter, S. P. L. Jones, and F. Aubke, Inorg. Chem., 9,2485 (1970). (5) M. Lustig and G. H. Cady, Inorg. Chem., 1, 714 (1962). (6) R. J. Gillespie and J. B. Milne, Inorg. Chem., 5, 1236 (1966). (7) R. J. Gillespie and M. J. Morton, Inorg. Chem., 11, 586 (1972). (8) P. A. Yeats, J. R. Sams, and F. Aubke, Inorg. Chem., 12, 328 (1973). (9) P. A. Yeats, B. L. Poh, B. F. E. Ford, J. R. Sams, and F. Aubke, J. Chem. SOC. A, 2188 (1970). (10) A. M. Qureshi, L. E. Levchuk, and F. Aubke, Can. J. Chem., 49, 2544 (1971). (11) R. J. Gillespie and E. A. Robinson, Can. J. Chem., 39, 2179 (1961). (12) G. H. Cady and J. M. Shreeve, Inorg. Synth., 7, 124 (1963). Notes (13) The interaction of SnC14 with S206F2 is rather vigorous and may lead occasionally to an explosion. It is advisable to warm the mixture rather carefully. Contribution from the Department of Chemistry, Stanford University, Stanford, California 94305 Reduction of Pyrazine Oxide, Free and Coordinated to Ruthenium(I1) M. A. Blesa and H. Taube" Received October 13, 1975 AIC50739B Coordination of N2O to Ru(I1) enormously increases the rate of reduction of the oxide by V2+ or by Cr2+.1 A possible explanation of the effect is that Ru(I1) assists in the reduction of the coordinated N20, with the internal and the external reducing agents cooperating in producing a 2e- reduction of N20. On the basis of this hypothesis, it seemed reasonable to suppose that pyrazine oxide when coordinated to Ru( 11) would also undergo reduction more rapidly than does free pyrazine oxide. Accordingly, we undertook to study the rate of reduction of both and - The expected effect was not observed, and as a result our understanding of how Ru(I1) enhances the reducibility of N20 has not been much advanced. Because results we have ob- tained may nevertheless be of interest in other contexts, we make a brief report of them here. Experimental Section Pyrazine oxide was prepared following the procedure described by Klein and Berkowitz.2 The product obtained was recrystallized from benzene and then subjected to analysis. Anal. Calcd: C, 50.0; H, 4.2; N, 29.2. Found: C, 49.4; H, 4.23; N, 29.3. The ir and uv spectra agreed well with those described.2 T h e ion R u ( N H ~ ) s C ~ H ~ N ~ O ~ + was prepared by mixing Ru- (NH3)sOH22+ with pyrazine oxide, the former in 10% excess, under an atmosphere of argon. After complexation was complete, saturated sodium bromide was added. The solid was collected, washed, and dried. Anal. Calcd for [ R U ( N H ~ ) ~ C ~ H ~ N ~ O ] B ~ Z : C, 10.87; N , 22.18; H, 4.33; Br, 36.14. Found: C, 10.56; N, 21.97; H, 4.28; Br, 36.98. Solutions containing V(I1) and Cr(I1) were prepared by standard procedures. The spectrophotometric method was used in determining reaction rates. In all cases, experiments were done under pseudo-first-order conditions, with the reducing agent being used in excess. For V(I1) in reaction with uncomplexed ligand, measurements were made at 214 nm; this wavelength is at a band maximum for pyrazine oxide, the product pyrazine showing much weaker absorption. Advantage was taken of the zyxwv P* - ?rd charge-transfer transition in measuring the rate of reduction of the complex of pyrazine oxide with Ru(I1). The band maxima for the reactant complex and the product3 J in acid solution coincide (A 527 nm) but there is enough difference in the extinction coefficients to make it possible to follow the reaction using light in the visible region of the spectrum. With Cr2+ as reductant, reaction is too rapid for the rate to be measured by ordinary