THEINFRARED SPECTRA OF NITROAND NITRITOCOMPLEXES
Sept. 20, 1958
4817
TABLE V
pM versus pH DATA OH
Ca + z
Mg+2
Srt2
3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0
2.00 2.09 2.71 3.83 5.52 7.39 8.93 9.96 10.50 10.62 10.63 10.63
2.00 2.03 2.33 3.09 4.23 5.83 7.33 8.36 8.90 9.01 9.03 9.03
2.00 2.00 2.11 2.82 4.54 6.43 7.98 9.01 9.55 9.66 9.68 9.68
(M+2) = 1 X 10-1 M Ba+? Cu+2
2.00 2.00 2.01 2.23 3.31 5.38 6.92 7.96 8.50 8.62 8.63 8.63
(DTPA) = 2 X 1 0 - 2 M Ni+l c o +a
8.29 10.28 12.01 13.90 15.87 17.78 19.33 20.36 20.90 21.01 21.03 21.03
parable data for EDTA.15 It is immediately evident that DTPA is a more effective chelating than EDTA a t high pH values due to the greater stability of the MY-3 chelate. However, a t lower PH values, due to the influence of the less stable hydrogen chelate, DTPA is in some cases less effective, e.g., in the and Mg+2systems. Chelates of the type M2Y- are not formed to any extent since it has been shown that $K,H, is independent of the concentration of metal ion. If ligand-metal binding in the hydrogen chelates involved only one terminal iminodiacetic acid group (15) S. Chaberek. Jr., Arch. Biochem. Biophys., 55, 3 2 2 (1955).
[CONTRIBUTION
FROM THE
8.26 10.20 11.68 13.19 15.07 16.97 18.51 19.54 20.08 20.20 20.21 20.21
6.32 8.31 10.04 11.91 13.89 15.80 17.34 18.37 18.91 19.03 19.04 19.04
Zn+Z
Cd+?
Fe+2
6.09 8.04 9.53 11.12 13.02 14.92 16.46 17.50 18.03 18.15 18.16 18.17
5.52 7.68 9.76 11.78 13.77 15.69 17.23 18.26 18.80 18.92 18.93 18.93
4.30 6.25 7.84 9.57 11.51 13.42 14.96 15.99 16.53 16.65 16.66 16.66
Mn
+
2.40 4.09 5.86 7.99 9.97 11.89 13.43 14.46 15.00 15.12 15.13 15.13
the stability would be of the same order of magnitude as the chelates of iminodiacetic acid or methyliminodiacetic acid. However, the chelates are very much more stable indicating a greater degree of ring formation. Several possibilities also exist for the binding in the MY-3 chelates; however, no definite choice can be made a s to the actual structures from these data alone. Acknowledgment.-The authors wish to express thanks to the Geigy Chemical Corporation for financial support of this work. NEW YORK53, N. Y.
DEPARTMENT O F CHEMISTRY, OSAKA UNIVERSITY RESEARCH INSTITUTE]
AND THE
OSAKA MUNICIPALTECHNICAL
Infrared Spectra of Metallic Complexes. V. The Infrared Spectra of Nitro and Nitrito Complexes’ BY KAZUO NAKAMOTO JUNNOSUKE ,~~ FUJITA AND HIROMU MTJRATA~~ RECEIVED FEBRUARY 21, 1958
-
The infrared spectra of nitro and nitrito complexes have been measured in the 5000 400 ern.-' region. The normal coordinate treatment of the [Pt(N02)4I2-ion has been carried out to give complete assignments. The following conclusions have been obtained: (1) in a series of nitro complexes of various central metals, the metal-nitrogen bond becomes stronger progressively in the order of [iKi(NO,)6]4- < [Co(N02)6]3-< [Pt(NOz)a]2 - - . (2) the spectra of nitroammine complexes can be correlated with the structure more easily in the KBr region than in the NaC1 region; (3) the structure of the nitro bridge O ,H .in NH3)aCo-OH-Co( NH& ion can be determined by the infrared study; (4) [Cr(NH&N02]2+ is spectroscopically
r(
“02’
1 3 +
shown to be a nitrito and not a nitro complex.
Introduction Recently Beattie and Tyrrel13 studied the infrared spectra of a series of nitroammine coniplexes, [Co(”3) 6- w ( NOz).](3--n) + in the 5000650 cm.-l region, and attempted to correlate the stereoisomerism and the number of nitro groups with the infrared spectra. It was found, however, that the spectra were too complicated to allow band assignment because the absorptions due t o nitro and ammine groups overlap each other. Faust and Quagliano4 also compared the infrared spectra of (1) Presented before the annual meeting of the Japan Chemical Society, April, 1957, Tokyo University, Tokyo, Japan. (2) (a) Department of Chemistry, Clark University, Worcester 10, Massachusetts; (b) Osaka Municipal Technical Research Institute, Osaka, Japan. (3) I. R. Beattie and H. J. V. Tyrrell, J. Chem. Soc., 2849 (1956). (4) J. P. Faust and J. V. Quagliano, Tars JOURNAL, 76, 5346 (1954).
trans- and cis- [Co(NH,),(N02)z]Cl. However, no substantial difference was observed between these two isomers, although the latter exhibits a more complicated spectrum than the former in the 7 4 3 p region. It is expected that a study of the infrared spectra of these nitroammine complexes below 650 cm.-1 will afford more information, since the Co-NH3 and Co-NO2 stretching modes as well as the wagging, rocking and twisting modes of the nitro group appear in this region, and the overlapping of the nitro and ammine bands may possibly be avoided. The infrared spectra of ammine complexes have already been studied extensively by Powell and S h e ~ p a r d ,and ~ Mizushima, et a1.6 In order to ( 5 ) D. B. Powell and N. Sheppard, J . Chem. Soc., 4495 (1956). ( 6 ) S. Mizushima, I. Nakagawa and D. hf. Sweeny, J . Chem. Phys., a6, IOOG
(ism).
KAZUO ~ A K A h I O T O JUNNOSUKE , FUJITA AND HIROMU MURATA
4818
VOl. SO
Cm. -I. 1200
l4UO
950
8
9
10
11
476
685
SOD
.
1 L
I -
7
850
16
12
17
18
454
435
416
22
23
24
L_
21
e. Fig. 1.-Infrared
absorption spectra of: (1) __ , [Pt(NOz)r]’-; - - - -, ( 2 ) [Co(XOz),]’-;
discuss the spectra of nitroammine complexes, it is necessary, therefore, to study the infrared spectra of nitro complexes and to give complete assignments based on the normal coordinate treatment. I n the present paper, the assignments of the infrared spectrum of [Pt(NO2)*l2-ion will be made bascd on the result of the normal coordinate treatmcnt. Combining these results with those of the amine complexes, the spectra of nitroammine coiiiplexes will be discussed. In connection with the nitro complexes, the infrared spectra of [Cr,OH---. (NH3)&02]C12 and (NHJ)JCO--OH-CO(NH~)~
[
“02’
1
Cis will be studied to determine the structure of the NOz group in these complex ions.
-*-*-.-
, (3) [Ni(iV02)6]*-.
indicate the infrared spectra of threc nitro coni plexes in the 5000-400 em.-’ region. I n order to give complete assignments, the normal coordinate treatment was carried out using [Pt(N02)4]2 - ion as an example. The detailed method of calculation is given in the Appendix. -4s is shown in Table 11, the agreement between the calculated and observed values is fairly good. According to thc results of the calculation, tlic bands a t 1440-1350 C I ~ . - and ~ 838-828 cm. - l are assigned, respectively, to the stretching and bciiding vibrations of the nitro group. The Pt-N stretching bands which are most interesting cheinically appear weakly near 450 cm.-’ in the infrared and a t 319 and 307 crii.-l in the Raman spectrum. The assumed force constant for this mode is 3.4 x
TABLE I INFRARED SPECTRA OF SITRO COMPLEXES (cM.-~) Compoutid
Asym. N-0 str.
Sym. h*-0 str.
NOZ bend
N o t wagg.
M-N str.
ONO- ion“ 1335 1250 830 ... .. K C a [Ni( n’02)6] 1355 1325 833 463 Ko [CO(NOz)61: 1396,1381 1332 834 F30 413 450 K*[Pt(NOdd 1436,1410,1380 1350 838,832,828 636,613 CHsNO; 1582 1384 G47 599,476 .. * A. Rosenheim and I. Koppel, 2. anorg. Chenz., 17, 35 0 F. A. Miller and C. H. Wilkins, .4nal. Chenz., 24, 1233 (1952). (1898). c E. Billmann, Z. anal. Chein., 39,2’34 (1900). d M. Vezes, Bull. SOG. chinz. France, 19, 875 (1898). e T. P. Wilson, J. Chenz. Phys., 11, 361 (1943). Only the nitro frequencies are listed in the above table.
Experimental
IO5 dyne/cm. which is nearly equal to 3.43 X IO5
dyne/cm. obtained for the Pt-CSN bond in Preparation.-The compounds used in this investigation were prepared by the usual methods according to the litera- K2[Pt(CN)4].gSince this value is comparable to ture given in each table. The purity of each compound was the force constants of the C-H and C-C stretching ~ checked by the measurement of the ultraviolet s p e c t r u t ~ i . ~ , modes in organic molecules, it is concluded that the Absorption Measurements.-The infrared spectra were Pt-NOz bond is fairly covalent. obtained by a Perkin-Elmer Model 21 double beam infrared As is discussed later, all the nitro complexes spectrophotometer using NaC1 and KBr prisms. The KBr disk method and the Nujol mull technique were employed to exhibit several sharp bands of medium intensity obtain the spectra of the NaCl and KBr regions, respec- between 630 and 560 crn.-l. Since, in our calcutively. The Ranian spectrum of a concentrated aqueous lation, the wagging and twisting vibrations of the solution of Kx[Pt(N0~)4]was obtained by a “Yukigosei” nitro group are not included, the observed bands lianian spectrograph. Results and Discussion I. Nitro Complexes.-Figure 1 and Table I (7) Y . Shimura a n d R. Tsuchida, Bull. Chein. SOC.J a p a n , 29, 311 (19563. ( 8 ) S Ysrnada, THISJOIJRXAI., 73, 1182 (1951).
near 600 cm.-l may be the wagging modes of the nitro group which usually have higher frequencies than the twisting modes. Further evidence to support this assignment is seen in nitrito and poly(9) D. hI. Sweeny. I. h’akagnwa, S . hIizushimn linno, ibid., 78, 880 (1!15t?).
:irid
J. T . Quag-
Sept. 20, 19%
THEINFRARED SPECTRA
TABLE I1 CALCULATED AND OBSERVED FREQUESCIES OF THE MENTALS I N THE [ P t ( K o ~ ) d ]I~O-N (CM.-') Vibrational modes
K-0 str.
Ca1cd.c
1347 307 847
-Obd--Infrared
Inactive Inactive Inactive In act i vc Inactive 1440
OF
FUXDA-
Kamanb
1360 319 842 I nac t ive Inactive Inactive Inactive Inactive 1325 307 835 Inactive 245
Pt-n' str. K'Oz bend. KOz twist." .. NO2 \vagg.* .. X-0 str. 1445 .. .. N-Pt-N bend." SO2 rock. 177 ? illactive N-0 str. 1338 Inactive Pt-I\; str. 295 NO2 betld. Inactive 832 .. Inactive NO2 twist." Inactive 269 N-Pt-x bend. ? NO* wagg." .. Inactive 1445 X-0 str. Inactive Inactive .. X-Pt-K bend.'' Inactive Inactive h-Op rock. Inactive Inactive 177 1410 1444 N-0 str. Inactive NO2 rock. 183 Inactive 185 .. ? NO2 twist.& Inactive 1313 Inactive N-0 str. 1335 Pt-n' str. 450 428 Inactive 833 867 Inactive NO2 bend. N-Pt-N b e d . ? 200 Inactive KO2 wagg." .. Inactive 636,613 a Out-of-plane modes. The reported Raniail lines of Na*[Pt(NOz)dl are 307, 321(p), 835, 847(p), 1324, 1364, 1412. Here (p) denotes polarized line. (Mathieu and Cornevin, J . chinz. phys., 36, 271 and 308 (1939)). The Pt-N and N-0 distances were taken as 2.02 and 1.22 A., respectively, accorditig t o the result of X-ray analysis. Furthermore, these angles were assumed: (Y = a' = p = 120°, 6 = 90" (see Appendix).
nuclear nitro bridge complexes which show no such bands near 600 cm.-'. Table I also compares the spectra of nitro complexes with those of CH3N02 (the C-N bond is covalent) and free ONO- ion. I t is interesting to note that the asymmetric nitro stretching frequency increases progressively in the order of ONO- ion < [Ni(NO&]"-< [Co (NO2j6I3-< [ P t ( N 0 2 ) 4 ] 2 - < CH3N02. As already pointed out by Beattie and Tyrrell, the separation between the asymmetric and symmetric nitro stretching frequencies increases as the metal-nitrogen bond becomes stronger. The symmetric stretching mode does not show a large shift as in the case of organic nitro compounds.10 Therefore the above result seems to indicate that the metal-nitrogen bond becomes stronger in the order of Ni is
482 1
THE INFRARED SPECTRA OF NITROAND NITRITOCOMPLEXES
Sept. 20, 1955
TABLE Y ISFRARED SPECTRA O F S I T R I T O COMPLEXES (CM.-') Compound
Sym. N O str.
NO2 bend.
1428 1468 14GO
1310 1065 1048
824 825 839
594
1516
1200
830
..
[Co(SH3)jS02]2' [Co(XHa)jOKO] + [Cr(SH3jsOSO] 2T 3 ;-a . -O H -/ (SH~)~CO-OH-CO(SH~)~
1
1x021
a
Nor
Asym. N O str.
Co-N str.
wagg.
..
..
Cr-N str.
.........
499 ?
.........
..
476,466,444
500
.........
-1.LYerner, -1.Grun and E. Bindschedler, Ann., 375, 123 (1910).
,OH\ complex. For example, in [ (IYHa);{Co-OH-Co\NOz' (NH3)s]Cla, the following structures are possible
not probable because of the close approach of the two oxygens of the neighboring nitro groups. Therefore, a structure such as shown in Fig. 3 was assumed in which all the four nitro planes are perpendicular to the Pt-N square plane.17
0
\ .......................... hf,
As is shown in Table V, the EO stretching frequencies of this complex are markedly different from those of nitro and nitrito complexes. This result may rule out the structure I11 since I11 is expected to exhibit similar frequencies to that of the nitrito complexes. Structure I1 also has a difficulty to explain the high asymmetric stretching frequency of this complex. Therefore, the structure I which has one Co-N and one Co-0 bond is most probable from the infrared study. Fig. 3.--Xssumed
TABLE VI THE Cr(III)-SH3 STRETCHING FREQUESCIES IN T'ARIOUS AMMISE COMPLEXES Cr-NHa str. band (cm
Compound
[Cr(NHa) e ] + [Cr(NH3)sC1]2+ [Cr(S H 3 )jOiSO l 2 + [Cr(S H 3 ) I2 +
model of [ P ~ ( K O Z )2 I- ] ion.
The point group of this model is D 4 h . Then, the thirty-three normal vibrations are grouped into ten classes as shown in Table VII. Among those, twenty-three are in-plane vibrations which are calculated in this paper. The remaining ten vibrations are out-of-plane and separable from the in-plane vibrations. l*
-1)
455 (broad, weak) 470,460,431 476,466, 444 448
TABLE VI1 OF THE SORMAL VIBRATIONSBELONGING TO EACHCLASSOF SYMMETRY CLASSIFICATION I
In-plane modesNO? Pt-S bend. bend.
s o . of vib.
NO str.
Pt-N str.
3 1 1 3
1 0
1 0 0
1 0 0
1
0
0
1
1
1
0 0 1 1 1
n
0
0 0 0
3 1 >
I
3 3 >
0
1
R-02 rock.
----Out-of-plane modes-.. wagg. NO2 twist. NO2 bend. Pt-N.
0 0 0
0 0
1
0
0
n
0 0 1
0
0
0 1
n
0 0
0 0
1
Appendix The following procedure was used in the calculation of the normal vibrations Of the [pt(N02)4]'ion. According to the X-ray analysis of Lambot16 the and the four nitrogen atomsform a square plane, each o-hT-oplane being tilted 690501 to the square plane. However, it is desirable to assume a model of higher symmetry to reduce the order of the secular equation'. It is evident that a planar structure the is (16) H. Lambot, Bull. Sci. Liege, 12, 463, 541 (1043).
7
0
0 1 0 0 0
1 0
0 0
0 1
1
0
o
0
1 1 0
0
0
1
0 1
1 0
0 0
1
0 0 0
Activity
Ranian Inactive Inactive Infrared Rainan Inactive Rntnan Inactive Rainan Infrared
(17) Since such a model is different from the actual configuration, t h e force constants obtained (Table X) may not be accurate. Nevertheless, this assumption was made because t h e main purpose of calculation is t o give band assignments, and not t o determine a n accurate set of the force constants. (18) I t is generally shown t h a t the interaction between the in-plane and t h e out-of-plane modes is fairly small when t h e Urey-Bradley field is used t o express the potential energy. (See, S. Mizushirna, "Structure of Molecules and Internal Rotation," Academic Press, Xew Y o r k , s.Y . , 1964, p. 315.) I n t h e present case, all t h e offdiagonal terms of the F-matrices and t h e G-matrices which represent the interaction between these two modes vanish, except the one with t h e N-Pt-N bending in the E, which is, however, estimated t o be fairly small.
Vol.
4s2s
Et,
so
4823
MERCURY(II)--OLEFIN ADDITIONCOMPLEXES
Sept. 20, 1958
A%,
E
BIE
Fil
=
4
= FI~*IC
2
FiiAIE
1 Fz2 = h - zFn + i F 1 ~ y
Fl2
=
Fia =
Fia
FizAlq
F34
=
0
(2R
=
F,Pl'
+ r)2Fl -
3
-r2Fl]
10 F2n
= F&ie
The symmetry coordinates for the in-plane modes are given in Table VIII. Using these symmetry coordinates, the secular equation was set up according to the procedure of Wi1s0n.l~ The G and Fmatrices are calculated as shoayn in Table IX. An Urey-Bradley type field20 was used to express the Potential energy. The values of the force constants which give the best fit with the observed infrared and Raman frequencies are given in Table X. (19) E. B. Wilson, J . Chent. P h y s . , 7, 1047 (1039); 9 , 7G (1941). (20) T. Shimanouchi, ibid., 17, 245, 734, 848 (1941).
[CONTRIBUTION FROM
THE
F33
=
FdlF
FORCE
FBI=
9
FOR
TABLE X coUsTANTs OF [pt(~0,),12-
Str. K(Pt-N) = 3 . 4 0 ICl(N-0) = 7 . 3 0
Bend. R(O-N-O)
= 0.15
HI(Pt-N-O) = 0.08 Ha(N-Pt-K) = 0 . 0 4
ION (106 DYNE/CM.)
Repulsive F ( O ....O ) = 3 . 0 W N . . . .N) = 0 . 2 F i ( P t . . . .O) 3 0 . 0 3
Using these values of the force constants, the calculations have been made according to the usual procedure,'S and the results are shown in Table 11. OSAKA,JAPAN
DEPARTMENT O F CHEMISTRY, MASSACIIUSETTS INSTITUTE
O F TECHNOLOGY]
Proton Resonance Spectra and Structures of Mercury(I1)-Olefin Addition Compounds BY F. A. COTTON AND J. R. LETO RECEIVED MARCH27, 1958 The proton resonance spectra of methyl ethyl ether, CH30CH2CH2HgOCOCH3and HOCH2CH2HgOH are reported The first two were measured in CC14 solution and the measured chemical shifts extrapolated to infinite dilution. The last compound was measured in basic D20 and shifts again extrapolated to infinite dilution. The results conclusively support the above structures for the mercury compounds on the basis of observed area ratios and spin-spin hyperfine structure The relative chemical shifts of the several types of methyl and methylene groups are in general accord with expectation from previous studies.
Introduction As part of a broad study of the nuclear resonance spectra and structures of the addition compounds formed by various metals with alkenes and alkynes, we have investigated the proton resonance spectra of two simple but typical olefin adducts of mercury (11) salts, uiz., CH&OOHgCH2CH20CHs and HOCH2CH2HgOH. Aside from its intrinsic in-
terest, this study serves a purpose in our over-all program of providing data on olefin-metal complexes for which there is good evidence that addition of HgX2 across the double bond to give a carbon-mercury(I1) u-bond has occurred.' It is found that, conversely, the proton resonance spec(1) For comprehensive discussion of this point see G. F. Wright, A n n . A;. Y. Acnd S c i . , 65, 430 (3057), and J . Chott, ChPm. Revs., 48, 7 (1951).
