July 5, 19.57
SPECTRA OF INORGANIC COORDINATION COMPLEXES
The influence of molecular shape upon the internal field is evident in the values of @ in Table I and the points in Fig. 1. For the roughly spherical molecules of the substituted methanes, the effect of the internal field is greater than that calculated by means of the Powles equation, a discrepancy which would be still greater if the correction for the effect of viscosity were not omitted. The flattening of the sphere to the roughly oblate spheroidal form of the substituted benzene and pyridine molecules re duces the effects of the field to amounts close to those calculated by means of the Powles equation, an apparent exception being 2,6-dimethylpyridine, the points for which lie close to the O’Dwyer and Sack curve. Elongation of the flattened structure as in the quinoline, isoquinoline and substituted naphthalene molecules reduces the effects of the field below those calculated by the Powles equation. That the decrease in field effect is not merely the result of increase in molecular volume is shown
[CONTRIBUTION FROM THE
3313
by the fact that pyridine and the monomethyl and monohalogenated pyridines and benzenes have about the same molar volumes as the tetrasubstituted methanes under consideration. The strong local fields of the highly polar cyanide and nitro groups raise the effects of field well above those calculated by the Powles equation for nitrobenzene and benzonitrile, but the effect is much smaller in the case of the larger 1-nitronaphthalene. It is evident that the macroscopic dielectric relaxation time of a polar liquid is usually greater than the molecular relaxation time but not nearly as much greater as is indicated by calculation based on the Lorentz internal field. The Powles equation and the identical first approximation obtained by O’Dwyer and Sack seems to be the best approximation for the calculation of the molecular relaxation time from the macroscopic, but it is a very rough approximation. PRINCETON, NEWJERSEY
DEPARTMENT O F CHEMISTRY,
UNIVERSITY O F NOTRE DAME]
Infrared Absorption Spectra of Inorganic Coordination Complexes.lash XII. Characteristic NH, Deformation Vibrations of Solid Inorganic Complexes
The
BY G. F. SVATOS, D. M. SWEENY, SAN-ICHTRO MIZUSHIMA,~ COLUMBA CURRAN AND J. V. QUAGLIANO RECEIVED JANUARY 19, 1957 The infrared spectra of a number of solid metal ammine complexes have been investigated. It has been possible to deter mine the three deformation vibrations of the ligated molecules in these complexes. The NH, degenerate deformation is observed in the region of 1650-1560 cm.-]; the NH3 symmetric deformation in the region of 1350-1150 cm.-l; and the NH3 rocking frequency in the region of 950-650 cm.-I. Each of these absorption bands has a characteristic absorption profile. A theoretical explanation for the range of these deformation frequencies is presented.
Introduction Infrared spectra of solid ammine coordination compounds of the transition metals have been subject to several investigation^.^-' The comparative ease of preparation and the wide diversity of substituents possible in this series have emphasized the importance of a definite characterization of the absorption bands, which may be attributed to the NH3 grouping upon complex formation. Mizushima, Nakagawa and Quagliano have recently characterized the deformation vibrations of coordinated ammonia molecules in Co(II1) ammines8 Using a Urey-Bradley type potential function, the frequencies of the degenerate and symmetric deformations and the rocking vibrations have been calculated for the Co(NH3)6+++ (1) (a) Paper XI in series, Spectvochim. Acta. in press. (b) Abstracted from t h e Ph.D. theses of G. F. Svatos, 1954, a n d D. M. Sweeny, 1955. Supported in part under A E C Contract AT(ll-1)-38, Radiation Project of the University of Notre Dame. Presented before t h e Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Pittsburgh, P a . , Feb., 1955. (2) Visiting Professor from Faculty of Science, T o k y o University. (3) J. LeComte and C1. Duval, Burl. soc. chim. Beiges, 151 12, 678 (1945); R . Duval, C1. Duval a n d J. LeCompte, Compf. rend., 824, 1632 (1947). 76, 5346 (1954). (4) J. P. Faust and J . V. Quagliano, THISJOURNAL, (5) D . G. Hill and A. F . Rosenberg, J . Chem. Phys., a2, 148 (1954). (6) M. Kobayashi and J. Fujita, ibid.,2S, 1354 (1955). (7) G. F. Svatos, C . Curran a n d J. V. Quagliano, THISJ O U R N A L , 7 7 , 6159 (1955). (8) S. Mizushima, I. Nakagawa and J . V Quagliano, J. Chem. P h y s . , 23, 1367 (195:).
ion. These calculated values were shown to be in good agreement with frequencies observed for a number of Co(II1) ammines containing coordinated ammonia molecules and, furthermore, the values calculated for the deuterated hexammine cobalt(II1) chloride, using the same set of force constants, agreed with the observed frequencies. The infrared spectra of a number of ammines have now been obtained to determine the effect of the nature and the oxidation state of the central metal atom on the frequencies of the three characteristic deformation vibrations of the coordinated ammonia molecules. Experimental Preparation of Compounds.-The compounds listed in Table I were prepared by methods similar to those given in the references in the last column. Most of the compounds were dried by heating under reduced pressure in an Abderhalden apparatus for several hours a t 110’. A11 other compounds listed in Table I1 were supplied by Dr. D. N. Sen .9 Absorption Measurements.-Spectra were obtained by means of a Perkin-Elmer Infrared Spectrophotometer Model 21 with a sodium chloride prism. Preparation of the potassium bromide disks was carried out according to the procedure of Stimson and O’Donnell’O as described in a previous article. The frequency values for the NH3 deformation vibrations are listed in Table 11. (9) D. N. Sen, P h . D . Thesis, University of Notre Dame, 1953. (10) M. hl. Stimson and hl. J. O’Donnell, THIS JOURNAL, 74, 1805 (1952).
3314
G. F.SVATOS, D. &f.
SWEENY,
s. h I I Z U S H I h f A , c. C U R R A N A N D J. V. QUAGLIANO
TABLE I ANALYSIS OF COMPOUNDS Component analyzed
Compound
%
Calcd.
NHa 38.20 [Co(”a)e.l CIS “3 44.04 [CO(”I)B] Cl2 XH3 17.93 [Ag(SHa)zIzsoi ”3 27.72 [CU(KH3)aJSOa.Hl.O 41.08 SH3 [Si(xH3)6]Cl~ SHa [Cr(NH&I Cl3 39.22 “3 34.96 [Cr(NH3)5C1]C12 [Co(NH&BrI Br2 XH3 22.18 [CO(NH3)5N021Clz SH3 32.62 NH3 30.74 [CO(NHa)6N03]Clz NHa 31.71 lCo(”s)sHzOl CL XH3 25.28 [CO(”S)~(H~O)ZI CIS trans- [Co(NHl)a(K O Z ) Z ] C ~ S H s 26.76 h-Hr [CO(NHI)I(NOZ)~] 20.60 SH3 ~CO(NH~)~CIIB~~ 25.09 KH3 32.62 [Co(NHa)jOi\’O]C1z SH3 30.98 ~ C ONH3)sSOil ( C1 [CO(XH3)jC03]S03,1/2H20 SH3 26.40 SHa 25.12 [ C O ( X ” ~ ) ~ OBr2.Hz0 H] KH3 [CO(NH~)~C~O~]B~.H B ~ 21.67 NH3 30.62 [CO(NH3)aC03]C1 K [ C ~ ( N H I ) Z ( ~ - ~ Z ) ~ ATH3 I~~ 10.77
TABLE I1 DEFORMATION FREQUENCIES IN C M . - ~FOR METALAMMINE COMPLEXES 96
Found
Ref.
37.94 43.71 17.58 27.34 43.83 38.77 34.58 22.06 32.38 30.64 31.58 24.99 26.71 20.57 25.20 32.73 30.98 26.11 26.10 21.76 30.35 11.19
10 11 11 11 11 11 11 12 13 14 11 15 11 11 16 13 17 18 19 20 21 11
Discussion The previous calculation* of normal frequencies for the NH3 ligand was based on the following potential function V = Z: 2:Ki(Aui)
Vol. i9
+Z1
Compound
1 [Ag(SH3)zIzSOc 2 [Co(”~)el cl2 3 [Ni(”&] clz 4 [CU(XH~)~]SO~.H~O 5 [Cr(xHt)e.Ic13 6 [Pd(NH3)11Clz 7 [CO(“3161 Cla 8 [Pt(NH3)41Clz 9 [Pt(SHs)jCl]Cl3 10 [Cr(NHa)5C1]Clz 11 [Cr(KH3)nN02]CIZ 12 trans- [Pt(KH3)2C12] 13 trans- [Pd(NH3)2Clz] 14 [CO(NH3)5NOz]C12 15 trans- /Co(NH3)~(SOg)P]Cl 16 [CO(NHa)a(SO2)3I 17 K [CO(ITH:j)g(NO2)rl 18 [Co(SH3)aC1]Brg 19 [Co(SH3)nBr]Rr~ 20 [Co(NH3)50H]Br2 21 [CO(SHa)sOSO]Clz 22 [CO(KH3)5HzO]CI3 23 cis- [CO(NHa)a(HzO)p]C1a NO3 24 [CO(SH3)sC031 25 [CO(NH3)rCOal C1 O~J 26 [ C O ( S H ~ ) S NClg 27 [CO(SHa):,SO4]Cl Br.HBr ( 28 [Co(S H a ) &CZO,)]
Degenerate
Symmetric
Rocking
1650 1610 1610 1615 1620 1610 1620 1570 1560 1600 1620 1605 1614 1595 1620 1630 1630 1600 1590 1620 1620 1620 1620 1603 1600 1600 1615 1625
1215 1158 1175 1285 1314 1304 1325 1360 1355 1290 1303 1295 1250 1315 1300 1390 1265 1310 1312 1303 1320 1325 1320 1305 1280 1315 1315 1310
738 650 678 732 757 82 7 82 7 850 933 721 768 815 736 850 840
813 790 840 832 806 845 835 850 830 850 85.5 830 533
$3ijriorJo ( A ~ i j ) ~
throughout the series, whereas the remaining two, H(HKM) and F(H. . .&I), depend considerably on +,z i F i j ( A p i , ) z linear terms the nature of the central metal, M. The calculation showed that the degenerate dewhere ri and rj are bond lengths with equilibrium values ri0 and yJ0; aij bond angles and qij distances formation frequency depends on H(HNH) and between non-bonded atoms. In addition K , H F(H. .H), the rocking frequency on H(HNM) and the symmetric deformation and F represent stretching, bending and repulsive and F(H. . .M), frequency on all four constants. It follows from force constants, respectively. The deformation frequencies depend on the bend- these relationships that the difference in the nature ing force constants H ( H N H ) and H(HXhf), and of the central metal atom should be reflected veri the repulsive force constants, F(H- . .H) and strongly in the value of the rocking frequency F(H- -&I), where M denotes the central metal. considerably in the symmetric deformation freOf these constants H(HNH) and F ( . .H) are the quency and little in the degenerate deformation same as those used for the calculation of the vibra- frequency. The frequencies of the deformation vibrations tions of ammonia (NH3), ammonium ion (NH4+), and the deuterated products (ND, and ND4+).23 fall in characteristic regions of the spectra for a11 Therefore, these two constants have the same value metal-ammine complexes reported. The degenerate deformation appears between 16.50 and 1500 (11) I. Bjerrum and J. P. McReynolds, Znorg. Syntheses, 2, 210 cm.-l, the symmetric deformation between 1350 (1946). and 1150 cm.-l and the rocking vibration between (12) H. Biltz and W , Biltz, “Laboratory Methods of Inorganic Chemistry,” 2nd E d., John Wiley and Sons, New Y o r k , S . Y . , 1928. 930 and 050 cm.-I. The absorption profiles of the (13) H. Diehl, H. Clark a n d H . H. Willard, Inorg. Syntheses, 1, 186 deformation are also quite characteristic. The (1939). degenerate deformation is broad and of moderate (14) H. F. U’alton, “Inorganic Preparations,” Prentice-Hall, New Y o r k . N . Y . , 1948, p. 92. intensity, the symmetric deformation is quite (15) S . Xi. Jorgensen, J . auakt. Chem., as, 237 (1881). sharp and very intense, and the rocking vibration (16) H. Hecht, “Preparative Anorganische Chemie,” Springer Verband is very broad and intense.24 lag, Berlin, 1961, p. 173. The effects of the nature and oxidation state of (17) S. M. Jorgensen, I.P a k ! . Chem., [?I 18, 221 (1878). the central metal atom on the deformation fre(18) F. Ephrdim and W. Flugl, H r ! s . Chim. A c t a , 7 , 724 (1924). (19) A. B. Lamb and K. J . hlysels, THISJ O U R N A L , 67, 470 (1945). quencies are revealed by the data in Table 11. (20) A. Werner, B e r . , 40, 4109 (1907). I t is evident that the rocking frequency decreases (21) S. &I.Jorgenson, Z. nnorg. Chem., 11, 425 (1896).
+
-
( 2 2 ) A. B. L a m b and E. B. Damon, THISJOURNAL, 69, 385 (1937). 193) I. Nakagawa and S . Mizushima, Bull. Chem. SOL.J a p a n . 28, 589 (1955).
(24) T h e spectrum of hexamminecobalt(1II) chloride has been reported in a previous paper.‘ See also D G. Hill and A. F. Rosenberg, J. C h e m . Phys., 24, 1219 (196ci).
July 5 , 1957
SYNTHESIS OF ETHYLENEDIAMINEPLATINUM(~~) AND (IV) BROMIDES AND IODIDES33 15
in the following order: Pt(1V) > Pt(I1) > Co(II1) plex itself on the ammonia deformation frequencies Pd(I1) > Cr(II1) > Cu(I1) > Ni(I1) > Co(I1). is seen also in the series of cobalt(II1) ammines Univalent silver is somewhat out of line, the am- (compounds 17, 16, 15 and 14). (The position of monia ligands in [Ag(NH&]+ having a rocking the rocking band a t 790 ern.-' in compound 17 is frequency slightly greater than that in [Cu- not accurately known as the NO2 group also ab(NH3)4]++. The presence of rocking frequencies sorbs strongly in this region). Both the rocking in the spectra of the hexammine Ni(I1) and Co(I1) and symmetrical deformation frequencies increase, complex ions indicates that the nitrogen-to-metal in general, with increasing positive charge on the bonds have covalent character; the relatively low complex. This increasing positive charge coincides frequencies along with the paramagnetism of these with increasing number of ammonia molecules in these Co(II1) complexes. complexes indicate sp3d2outer orbital type bonds. The replacement of the carbonate group in the The rocking frequencies show a large variation and are thus very sensitive to the nature and oxida- [Co(NH3)&03]+ ion (compound 24) by a sulfate tion state of the central metal ion. This is under- group (compound 27) has no effect on the rocking standable from the above discussion of the nature frequency, and replacement by an oxalate group (compound 28) has very little effect on either the of the rocking vibration. The symmetrical bending frequencies of coordi- rocking or the symmetric deformation frequencies. ions ~ (compounds 1s to 21 nated ammonia molecules show a similar variation I n the [ C O ( N H ~ ) & ] + with the nature of the N-L!I bond but the percen- and 26), an appreciable lowering of the rocking tage difference in frequency in going from the and symmetric deformation frequencies occurs Co(I1) to Pt(1V) ammines is not so great as for only where X is a hydroxyl group. The replacethe rocking frequencies. Moreover, the degenerate ment of an inner chlorine atom by a nitro group in frequencies show little variation with the nature the [Cr(NH3)&1]++ ion (compounds 10 and 11) of the N-M bond. These observations are also in results in an appreciable increase in the these deforaccord with the foregoing discussions of the natures mation frequencies. The spectra of these metal ammine complexes of the symmetric and degenerate deformation vibraare being determined in the cesium bromide region tions. The neutral Pt(NH3)zClZ molecule (12) has a in these laboratories t o study the nature of the lower rocking and a lower symmetric deformation lower frequencies, as reported in a previous paper.*j frequency than the [Pt(NH3)4]++ion (8) and a ( 2 5 ) D. M. Sweeny, I. Nakagawa, S. Mizushima and J. V. Quaglisimilar effect is observed in the Pd(I1) compounds ano, THISJ O U R N A L , 78, 889 (1956). (13 and 6). The effect of the charge of the com- NOTREDAME,INDIANA
>
[CONTRIBUTION FROM THE
DEPARTMENT OF
CHEMISTRY OF THE UNIVERSITY OF TEXAS]
The Synthesis o€ Certain Ethylenediamineplatinum(I1) and (IV) Bromides and Iodides1 BY GEORGEUT.WATTAND ROBERTE. MCCARLEY RECEIVED MARCH16, 1957 Methods for the synthesis of ethylenediamine coordination compounds of certain halides of platinum( 11) and ( I V ) in high yield and high purity are described. It is shown that [Pt(en)Brzl and its isomer [Pt(en)g]PtBra may be separated quantitatively owing t o the solubility of the former in liquid ammonia a t -33.5'.
In the course of studies on the lower oxidation states of platinum,2 we have had occasion to prepare numerous ethylenediamine coordination compounds of platinum halides. Although many of the corresponding chlorides have been synthesized and are well characterized, they are not desirable as starting materials for reactions in liquid ammonia owing to their generally low solubility. Accordingly, the necessary bromides and iodides were prepared. The syntheses described below either correspond to compounds not previously reported or represent new and/or improved procedures.
Experimental Methods.-Platinum, when present as the only nonvolatile component, was determined by ignition t o the metal; otherwise, platinum was reduced t o the metal with ( 1 ) This work was supported in p a r t by the U. S. Atomic Energy Commission, Contract AT-(40-1)-1639. (2) G. W. W a t t and R. E. McCarley. THISJOURNAL, 79, in press (1957).
hydrazine, dissolved in aqua regia, and determined spectrophotometrically.a Halogens were determined as silver halide; where halogen was covalently bonded in complexes, i t was displaced with ethylenediamine prior to precipitation. All X-ray diffraction patterns were obtained using a Hayes unit, Cu Kor radiation, an Ni filter, a tube voltage of 35 kv., a filament current of 15 ma. and exposure times that varied with the nature of the sample. All of the X-ray diffraction data reported here are assembled in Table I and include only the six most intense lines for each compound for which such data are riot already available; more nearly cotnplete data are tabulated elsewhere.' For potentiometric titrations, the potential was measured with a Leeds and Northrup type K potentiometer, a platinum indicator electrode, and a saturated calomel reference electrode. Materials.-Unless otherwise indicated, all chemicals employed in this work were reagent grade materials that were used without further purification. Hexabromoplatinic acid was obtained by dissolving finely divided platinum in bromine and concentrated hydrobromic acid followed by boiling t o remove excess bromine and acid. Massive platinum was dissolved in aqua regia and the re(3) G. H. Ayres and A. s. Meyer, Jr., Anal. Chem., 23, 299 (1951). (4) R. E. McCarley, Dissertation, The University of Texas, 1956.
