RAMAN SPECTRA OF GERMANIUM AND LEADTETRACHLORIDES
Oct., 1948
3. The effect of a C-methyl group on the spectrum of 4dimethylaminoazobenzene and the possible structura.1 relationship between the parent FROM THE CHEMICAL
[(;ONTRIBUTION
3463
dyes and the polar bound dyes formed in vivo are discussed. RECEIVED FEBRUARY 9,1948
LABORATORIES OF THE UNIVERSITY OF
CALIFORNIA]
Raman Spectra of Germanium Tetrachloride and Lead Tetrachloride BY JOHN T. NEU AND WILLIAMD. GWINN The molecules of the type XU4 have been the subject of considerable investigation and the Raman spectra of a large number of these compounds have been measured and tabulated.’ Professor Hildebrand2 has for some time been especially interested in the tetrahalide molecules and has recorded that the distance from the cen-
t
1
\
700 I
6oo
be expected. Haun and Harkins3 have noted a possible alternate value for V I , which would give a point closer to the one predicted by the graph. It was, therefore, considered worth while to repeat the determination of the Raman spectrum for germanium tetrachloride and to check the value of 1’3.
tC Y -
s ‘ ,
loo
1
LI
0
1.8
1.9
20 21 2.2 2.3 2.4 M-CI distance. Fig. 1.- Raman frequencies plotted against central atom-chlorine distance in
1.7
tral atom to the halogen atom plotted against the Raman frequencies V I and v2 gives generally smooth curves as shown in Fig. 1. The v3 frequency for germanium tetrachloride on such a plot, however, shows a considerable deviation from what might (1) G. Hcrzberg, “Infrared and Raman Spectra,” D. Van Nostrand. X e u York I\‘ Y. 1945 (2) J I1 Hildebranil J C/iev8 Phys , 15, 727 (1947)
25
A.
It also seemed possible that the above-mentioned graph might be used t o predict Raman frequencies of tetrahalides where the central atornhalide distance was known. Lead tetrachloride appeared to be a suitable compound with which to verify such a prediction, and a t Professor Hildebrand’s suggestion, the determination was made (3) 1IdUll and I-liirkins
* l l i I b J O U H ~ A L ,6 4 ,
31171 (I‘J3LJ
3464
JOHN
Vol. 70
T.NEWAND WILLIAMD. GWINN _ .
I
!
0
0)
2 F40 0.1
I
1
(J.5
1.7
1.8
Fig. 2.-Force
2.0 2.1 2.2 2.3 2.4 IN-Cl distance. constants plotted against central atom-chlorine distance in b. 1.9
2.5
exciting line. The exposure required for germanium tetraExperimental chloride was approximately equal to that required for carApparatus.--A Steinheil type GH spectrograph was used bon tetrachloride, while lead tetrachloride exhibited very with three glass prisms, f/10 collimator and camera lenses, strong scattering, due to a close absorption band, and reand a slit width of 0.025 mm. Eastman Kodak Co. 103F quired only about one-fiftieth of the exposure necessary for spectroscopic plates were employed. An iron arc refcrence carbon tetrachloride. spectrum was placed on the plate in such a way that it parApparatus for obtaining qualitative polarization data tially overlapped the Raman spectrum. Shifts were as- was assembled using a combination of schemes cited by signed by interpolation from the nearest iron lines. Dis- Glockler and Balier.j Two horizontdl mercury arcs lying placements are tabulated in wave numbers in oacuo iis de- in a plane inclined a t 43' to the vertical to eliminate differtermined by conversion of X in air to wave numbers in ential reflection a t the prism surfaces were used in conuucuo from Kayser's "Tabelle der Schwingungszahlen." junction with baffles to produce planar and perpendicular The light source consisted of twelve mercury arcs G.E. incident light. A quartz Wollaston prism, inclined so that type H-2) in a circular arrangement around the sampje the axis lay in the plane of the incident light, was placed tube. In the case of germanium tetrachloride, the 4358 A. behind the slit in the collimator tube. With this arrangeline was used for excitation with filter solutions of satu- ment, a single exposure gave two representations of the rated sodium nitrite, saturated praseodymium chloride, spectrum, one above the other (and shifted slightly), in and rhodamine 5GDN extra dye as described by S t a m n ~ , ~which the polarized lines appeared less intense in one band interposed between the light source and the sample in three than in the other. concentric Pyrex cylinders. Lead tetrachloride strongly Preparation of Compounds.-The lead tetrachloride was absorbed the 4358 A. line and consequently the 54131 b. prepared by passing chlorine gas into a mixture of lead line was used for excitation. The outer filter in this, case chloride and concentrated hydrochloric acid cooled to 0".6,' Chloroplumbic acid, HzPbC16, was formed and was contained saturated sodium chromate, and in the place of the two inner filters a set of b d e s was employed to make converted t o the stable insoluble ammonium salt, ("4)sthe incident light essentially perpendicular t o the sample ( 5 ) Glockler and Baker, J. Chem. P h y s . , 11, 440 (1943). tube and hence reduce Rayleigh scattering of the excitation (6) V. F. I'ostmikov and A. I. Speranskil. J. Gen. Chcm. ( T i .9 S line, thus facilitating detection of Raman shifts close l o the ~~
14) R G Stamm. I i f d E n p Chrm A n a l . E d . . 17. 318 (194!5)
R.1, 10, 1328 (1940) (7) Friedrich. Rsr.. $6, 1434 (189.7)
SOMEHALOBENZENE PHOSPHONIC ACIDS
Oct., 1948
3465
PbC16, by addition of ammonium chloride. This salt, when treated with concentrated sulfuric acid a t O o , separated out lead tetrachloride as a dense oily, yellow liquid, which was purified by washing with concentrated sulfuric acid. The liquid was kept at 0 ” while the Raman spectrum was being taken. Germanium tetrachloride was made by boiling germanium dioxide with concentrated hydrochloric acid in a stream of hydrogen chloride gas.8 The escaping hydrogen chloride gas carried the germanium tetrachloride through a water condenser into an acetone-Dry Ice-bath where germanium tetrachloride was frozen out of the gaseous mixture. The product was purified by distillation and treatment with sodium carbonate.
The Raman shifts obtained for germanium tetrachloride were found to be essentially the same as those found by the two previous investigators (Table I). With long overexposure, however, no trace of a line could be found in the region between 500 ern.-' and 600 cm.-l, so i t was concluded that the value of 452 cm.-l for v3 was the correct one rather than the possible alternate value listed by Haun and Harkins. The deviation of v3 may be explained by consideration of the masses of the atoms involved. VI (A1) and v2 (E) represent, respectively, a “breathing” and a bending freDiscussion quency. Both are independent of the mass of the Considerable difficulty was encountered in lo- central atom, while v3(F2) and vq(F2) represent vicating the Raman frequencies v2 and v4 in the case brations in which the central atom as well as the of lead tetrachloride since they lay close to the ex- chlorine atoms are displaced. It would, thereciting line and were obscured by the background fore, be expected that the deviations in the latter two frequencies might occur, as shown by the v3 from it. Plate tracings showed a peak a t 90 cm.-l, but on only one plate were two separate lines re- frequency of germanium tetrachloride. I n an attempt to eliminate the effect of the mass of the solved, these appearing at 85 cm.-’ and 93 cm.-l. The latter values are inclosed in brackets in Table central atom, force constants calculated by the I. The frequencies obtained for lead tetrachloride method of RosenthallO rather than frequencies are in satisfactory agreement with those which were plotted against the central atom-chlorine would have been predicted by extrapolating the distance as shown in Fig. 2. It will be noted that in this plot the germanium tetrachloride shows no curves in Fig. I,. marked deviations. TABLE I A more complete discussion of the correlation of the Raman spectra with metal-halogen disRAMANFREQUENCIES OF GERMANIUM TETRACHLORIDE tance is given by Hildebrand.2 Investigator VI VI
Haun and Harkins? Schneiderg The authors
397(10)
Y4
V2
132(6)
451(1) 171(6) or 508 396 134 453 172 397(10) P 132(2) D 452(1) D 171(3) D
Summary
For germanium tetrachloride, the correct value of v3 is 452 ern.-', and the deviation from the value predicted by plotting the metal-halide distance RAMAX FREQUENCIES O F LEADTETRACHLORIDE against Raman shift may be explained by considThe authors 227(10) P 90(3) D 348(3) D 90(3) D eration of the mass of the germanium atom. The [or 851 [or 931 Raman frequencies of lead tetrachloride are essentially what would have been predicted. ( 8 ) Foster, Drennan and Williston, THIS JOURNAL, 64, 3042 (1942). (9) K. W. F. Kohlrausch, “Der Smekal-Raman-Effect, Erganzungsband,” 1981-1937, J. Springer, Berlin, 1938.
[CONTRIBUTION FROM
THE
(10) J. E. Rosenthal, Phys. Rev., 46, 538 (1934); 46, 730 (1931).
BERKELEY 4, CALIFORNIA
RECEIVED JUXE 5 , 1948
CENTRAL RESEARCH DEPARTMENT, M o z r s ~ ~ CHEMICAL ro Cu.1
Synthesis of Aromatic Phosphonic Acids and their Derivatives. 11. Some Halobenzene Derivatives BY GENNADY M. KOSOLAPOFF Since the scientific literature contains the syntheses of only the p-chloro- and the p-bromo-benzenephosphonic acids, i t was felt advisable to prepare the possible isomers of halo-benzenephosphonic acids containing the principal halogens. This paper describes the syntheses of the m- and the p-isomers of the chloro-, bromo- and iodobenzenephosphonic acids, and includes the preparation of the related (p-chlorobenzene)-(9-aminobenzene)-phosphinic acid. The 9-chloro derivative was prepared in the ( 1 ) Michaelis. A n x . , 293. 193 (1896)
manner already described2 and was used for the preparation of phosphanilic acid according to B a ~ e r which ,~ was readily converted into the piodo-acid by the diazo-reaction. The preparation of the $-bromo-acid was conducted by our modified Michaelis reaction,2 in the course of which i t was found that considerable debromination took place, apparently through the action of the aluminum chloride catalyst. The m-isomers were prepared from benzene(2) Kosolapoff, THIS JOURNAL, 69. 2020 (1947) (3) R a n e r
