SOTES
2066
T'ol. 66
NOTES INFRARED SPECTRUM OF NITRYL PERCHLORATE
ported a t 2358 in S02RF4 solid,6 2360 in N02BF4 solution in HN03,8 2364 in NOzPF6 solid,6 2358 in S02SbF6 solid,6 2375 in NZO5 (SOz+NO3-) BY J. R. SOULEN AND W. F. SCHWARTZ solid,g and 2360 in anhydrous HN03 and H N 0 3 solutions in H z S O ~indicating ,~ the presence of S O z + Research and Development Laboratorzes, Pennsalt Chemicals Corpor atzon, Wyndmoor, Pa in these. One other report lists this absorption in SOZBF4 solid at 2384-2395 cm.-', but this Rerewed Aprzl 1 1 , 1961 worklo has been criticizede because of possible The ionic structure of solid nitryl perchlorate, reactions with cell windows. NOz+C104-, has been amply proved by Ramanl.? The broad absorption centering around 1100 and X-ray3 studies. Its vibrational spectrum thus cm.-l is v3 of C104-, and appears very similar to should consist of the superimposed spectra of the that found in "&lo4, NaC1O4.Hz0, KC104, NOz+ and c104- ions. In addition to the Raman and .11g(C104)2.l1 il weaker absorpbion a t 937 work, a limited infrared study also has been made em.-' is v1 of C104-. This is a Raman active, of this omp pound.*^^ However, two fundamental infrared inactive fundamental.*J However, some vibrational frequencies of the SOz+ ion in nitryl dist'ort'ionof the tetrahedral C104- structure allows perchlorate apparently have not yet been reported. this absorption in t'he infrared spectrum of nitryl In addition, very little information exists on the perchlorate. It' also is evident as a weak absorplowest fundamental vibrational frequency of N02f t'jon in S&C1o4, KC1O4, and lUg(C104)z.11 The in any of its ionic compounds. We here report strong absorption a t 625 cm.-l is due t o v4 of C104-. the infrared absorption spectrum of N02C104and This has been reported previously in KOZC104 at discuss it in terms of the vibrational frequencies about the same frequency in the infrared4J and of its constituent ions. at 626 in its Raman spect'rum.2 Infrared or Raman In Fig. 1 the 2-15 p region was obtained with studies of a number of other perchlorates, includNaCl optics, and the 15-20 p region with CsBr ing those of XH4+, Na+, K+, Mg+, and HzO+, optics. No significant absorption occurred from show this absorption prominently, with its maxi2 0 4 0 p . Both spectra were obtained in a Nujol mum in t'he range 620-631 cm.-1.2,5j12-14 mull and polyethylene films mere used to protect TABLE I the windows from attack, as has been found necesCOMPARISON O F TTIBR.4TIONAL FREQUENCIES OF sary with various nitryl compounds here and elseA N D COza The nitryl perchlorate, obtained from Nitryl ion, NOz Callery Chemical Co., was pumped overnight at in in 10 g pressure to remove volatile contaminants NOzNOzwhich can form by hydrolysis. It TTas protected NO, COzi Activity Vibrational mode ClOa rigorously from atmospheric moisture in subse(1340)8 1396* 1400d Symmetric stretching Raman only quent handling. Analysis showed 23.95% C1, 667 670' 53Se Bending Infrared only 9.7201, N (calculated for NOzC104: 24.37% C1, Antisymmetric stretching Infrared only 236OC 2375' 2349 9.63% N), and its X-ray powder diffraction pattern =All values in cm.-'. 6 Ref. 2. this work. Obagreed well with that published previously.' served by J. Chkdin (Thesis, Paris, 1937); reBecause of its extreme deliquescence, the nitryl ported originally subsequently by him and others. Ref. 9. G. perchlorate was mulled and the absorption cell Herzberg, "Infrared and Raman Spectra of Polyatomio components were assembled in a well dried inert Molecules," D. Van Xostrand Co., Inc., New York, N.Y., atmosphere box, and the spectra were obtained 1945, pp. 272-273. IJnder low resolution. Under higher this is two lines, at 1285.5 and 1388.3 ern.-', with a Perkin-Elmer 21 or 221 spectrophotometer resolution due t o Fermi resonance. This does not occur with KO*+ immediately on removal. The absorptions marked because vi is not approximately 2v9, as occurs with COz. with dots in Fig. 1 also were obtained in blank The final absorption in Fig. 1 at 570 cm.-I must runs using Nujol alone between polyethylene films, be the low frequency fundament'al v z of KO2+. and are thus of no interest. Significant in the spectrum are the absorptions In dinit'rogen pentoxide, S02+N03-, this has been a t 2360, 1100 (middle of very broad band), 937, foundgat 538 cm.-l. XO2+ and C 0 2 are similar, linear, symmetric 625, and 570 cm.-l. That a t 2360 cm.-' is the v 3 fundamental of KOz+. This has been re- species containing 22 electrons. Their vibrational +
VI
YZ
6
f
Q
(1) C. K. Ingold, D. J. Millen, and H. G. PooIe, Nature, 168, 480 (1946). (2) D. J. Millen, J . Chem. Soc.. 2606 (1950). (3) E. G. Cox and G. A. Jeffrey, Nature, 162, 259 (1948). (4) D. J. hIillen, J . Chem. Soc., 2611 (1950). ( 5 ) H. Cohn, %bad., 4282 (1952). (6) D . Cook, S.J . Kuhn, and G. A. Olah, J . Chem. Phgs , 83, 1669 (1960). (7) H. G. Norment, P I, Henderson, and R. L South, Anal. Chem., 32. 797 ,1960).
(8) R. A. Marcus and J. hf. Fresco, J . C'hem. Phys.. 27, 564 (1967). (9) R. Teranishi and J. Decius, i b i d . , 22, 897 (1953). (10) R. W. Sprague, A . B. Garrett, and H. H. Sisler, J . A m . Chem. Soc., 82, 1062 (1960). ( I 1) F.A. Miller and C. H. Wilkins. Anal. Chem.. 24, 1283 (1952). (12) E'. A . Miller, G. L. Carlson, F. F. Bentley, and W. H. Jones Spectrochim. Acta, 16, 153, 213 (1960). (13) 0. Redlich, E. X. Holt, and J. Biegeleisen, J . A m . Chem. Soc.. 66, 13 (1944). (14) D. J. hlillen and E. G. Vaal, J . Chem. SOC.,2913 (12156).
2067
YOTES
Oct., 1962
MICRONS 15
6
17
16
18
19
PO
04
z 06
NICL *, CaEa I
5000
3000
2000
1500
1000
,
I
900
700
800
600
500
CM.-‘.
Fig. 1.-Infrared
absorption spectrum of nitryl perchlorate.
spectra thus should resemble each other. In Table I their fundamental vibrations are listed. These agree exactly in activity and rather closely in frequency, with the exception of the v 2 bending mode which occurs a t a distinctly lower frequency (15 to 20%) in KO2+ than in COz. Discussion of the CIOIL- fundamental frequencies is sufficiently ~ o m p l e t ethat ~ , ~it need not be repeated here. Acknowledgment.-The authors are grateful for the considerable assistance of Niiss Ruth Kossatz and her staff of the Infrared Department in carrying out this work. It was supported in part by the U. S. Air Force.
However, it is barely resolved from the envelope due to the other CY- and P-protons. Replacement of the @-hydrogens by deuterium removes all proton-proton spin coupling in the backbone hydrocarbon chain and allows the a-protons in isotactic, syndiotactic, and heterotactic environments to be resolved clearly under appropriate conditions. The proton resonance spectrum of poly-P,b-dideuteriostyrene has been reported previously, but the experimental conditions were not suitable for resolution of the individual peaks.8
Experimental The proton resonance spectra were obtained in a manner described previously.4 The spectra were obtained on 15 wt. % solutions of polymer in benzene enclosed in a sealed tube at 100’. Peak positions are listed in p.p.m. to high PROTON RESONANCE SPECTRB ,4KD field of benzene as an internal reference. The p,p-dideuT A c r I C r w OF POLYSTYRENE AKD teriostyrene was obtained from Merck, Sharp and Dohme of Canada Ltd. and was reputed to be of better than 98% IlEUTERIOPOLYSTYRENES1~2 isotopic purity. The polystyrenes were prepared by standBY S.BROWNSTEIN, S. BYWATER, AND D. J. WORSFOLD ard methods using anionic, cationic, and free radical initiators as described before for a-methylstyrene.4 Dzvzszon of A p p l i e d Chamastry, Nataonal Research Counczl, Ottawa, Canada Recczved Aprzl 1.4. 1988
Results
It has been shown that there are large solvent
effects upon chemical shifts when aromatic moleObservations of polymer tacticity by proton cules are dissolved in aromatic ~ o l v e n t s . ~Adresonance spectroscopy have now been made on vantage was taken of this fact to maximize the several polymer sy~tems.3-~However, only with chemical shifts of the a-protons by choosing a polymethyl methacrylate and poly-a-methylsty- solvent which shifted them relative to the other rene have peaks due to isotactic, syndiotactic, and protons in the molecule. Benzene was found to heterotaetic environments been clearly resolved. have the greatest effect of the many solvents Usually, spin coupling of protons on adjacent which were tried. The spectrum of isotactic carbon atoms produces several lines for each polystyrene in benzene as solvent is shown in Fig. chemically unique species and when their chemical 1. It may be compared with one published preshift is small compared to the spin coupling between v i o u ~ l y to , ~ show the improvement in separation them, only a broad envelope of absorption is ob- of peaks which may be obtained by appropriate tained. One method of removing this obstacle choice of solvent. For comparison, the spectrum is to substitute deuterium for some of the protons. of a polystyrene polymerized by sodium naphthenide The smaller spin coupling constants and almost in tetrahydrofuran is included. This polymer infinite chemical shift combine to simplify the is primarily syndiotactic, as will be shown by the spectrum This has been done with polypropylene, measurements on a deuterated sample. but the choice of sites for deuterium substitution Line widths in proton resonance spectroscopy was such that some chemically non-equivalent are a function of the viscosity of the medium.’O protons were spin coupled.6 As a result, peaks For polymer solutions the macroscopic viscosity due to all three possible tacticities could not be is not the significant quantity since the line width resolved clearly. A separate peak for the a- of the solvent is generally much narrower than proton in isotactic polystyrene has been r e p ~ r t e d . ~those of the protons in the polymer chain. The (1) Issued as N.R.C. No. 7014. degree of segmental motion and internal rotation (2) Presented in part a t the symposium on “Spectroscopy of High along the polymer chain appear to be primarily Polymers,” American Chemical Society National Meeting, Atlantic responsible for broadening of the absorption peaks. City, 1962. (8) F. A. Bovey, G. V. D. Tiers, and G. Filipovich, J . Polgmer Sei., (3) F. A. Bovey and G. V. D. Tiers, J. Polymer Scz., 44,173 (1960).
(4) 5. Brownstein, S. Bywater, and D. J. Worsfold, Makromol. C h e n . , 48, 12‘7 (1961). ( 5 ) U Johnsen, J. Polymet Sci., 64,56 (1961). (6) F. Stehling, Paper #45,Division of Polymer Chemistry, American Chemical Society National Meeting, Washington, March, 1962. (7) R. J. Kern and S. V. Pustinger, Nature, 186, 236 (1960).
38, 73 (1959). (9) A. A. Bothner-By and R. E. Glick, J. Chem. Phys., 26, 1651 (1957). (IO) J. A. P o p h , W. G. Schneider, a n d H. J. Bernstein, “High Resolution Nuclear Magnetic Resonance,” McGraw-Hill Book Co., New York, N. Y., 1959, p. 204.
