INFRARED SPECTRA OF ? ~ ~ A L O N A TMETAL O COMPLEXES
Jan. 20, 1959
TABLE 11 QUANTITATIVE ELECTROS DIFFRACTIoS DATAFOR
CARBON
SUBOXIDE Feature Max. Min.
1 1
4 4
5 7
7 8
10 10 12 13 14 15
PO
1
14.08 18.38 30.50 34.61 37.86 47.04 50.75 54.52 63.15 66.66 75.81 79.80 92.65 108.80
1.010 1.004 1.003 1.004
d P o
2
3
0,999 1.001 0.995 ,998 ,999 ,992 1.001 0.995 0.904 1.000 1.004 0.994 1.020 1.025
0.983 ,998 ,982 ,995 ,998 ,981 ,998 ,988 .987 1.002 0,983 0.983
1.009
1.001
0.007
0.006
0.902 0.009
1.011 0.995 1.005 1.007 1.006 1.003 1.016
... 1.026 1.029
... -
1.016
~
Mean Av. dev. from the mean
TABLE I11 PRINCIPAL PARAMETERS FROM ACCEPTABLE h I O D C L S Parameter, A. 1 2 3
c-0 c-c
1.150
1.202
1 .I61 1.281
1.171 1.270
experimental curve is a visual curve, they were considered as barely acceptable. The quantitative
[CONTRIDUTIOS PROM THE
DEPARTMEST OF
%Si
electron diffraction data are shown in Table 11. The parameters calculated from the three models are listed in Table 111. The final parameters of carbon suboxide by the radial distribution curve and the correlation procedure are
c-o
= 1.16 =t0.015 A.
C-C = 1.28 f 0.015
A.
It should be noted that the uncertainties determined in this investigation are much smaller than those reported in the earlier investigations3-j which employed the visual method with non-sectored plates with the data extending to about q = 70 a t the most. The C-C distance obtained in this investigation is smaller than the C-C distance in ethylenes and ketene.15 This is possibly because of the greater multiple bonding in carbon suboxide. The C-0 distance in ( 2 3 0 2 agrees very well with the C-0 distances in ketene and carbonyl fluoridelj but is less than the C-0 distance in aliphatic ketones.16 Acknowledgments.-The authors’ thanks are due to Professor Henry Feuer and Mr. R. Miller for their assistance and advice in the preparation of carbon suboxide. (15) T. T. Broun and R . L. Livingston, T i m J O U R N A L , 74, G O 8 1 (1952). (16) C. Romcrs and J. I3 G Creutzberg, Rec. f m v . C / I ~ ? J Z , 7, 6 , 331 (1956). LAFAYETTE, 1NDIAS.l
CHEMISTRY, UKIVERSITY O F NOTRE DAME]
Infrared Absorption Spectra of Inorganic Coordination Complexes. XVIII. Studies of Malonato Metal Complexes’
Infrared
BY 11. J. S C I I ~ R I EICIZIRO L Z , ~ NAKAGAWA, ~ SAN-ICIIIRO MIZUSIIIMA~~ AND J. V. QU.AGI,IANO’C RECEIVED AUGUST1, 1958 Tlie infrared spectra of maloiiic acid and simple metal nialoiiates have beeit iiieasurcd iu the S a c 1 region. Tlie observed bands are assigned by comparison with the frequencies reported for simpler molecules of similar structure for which normal vibration calculations are available. The spectra of the malonato metal complexes of Fe(III), C r ( I I I ) , Al(III), Cu(I1) and Pd(I1) are interpreted by correlation with the spectra of the alkali metal malonate salts. The nature of the oxygen-to-metal bonds present in these complexes can be determined indirectly from the observed values of the 0-C-0 stretching frequencies.
Introduction
A variety of organic chelating agents are known which involve one or more carboxylate ions as donor centers. Previous studies3 indicate that in nickel(II), copper(I1) and zinc(I1) complexes with glycine the resonance structure of the carboxylate ion is essentially maintained and the bonding between the central metal and the carboxylate ion is essentially ionic in nature. Similarly, EDTA4 and (1) Paper X V I I in series, Speclrochim Acta, in press Supported in p a r t under A E C Contract AT(ll-1)-38, Radiation Project of t h e University of h’otre Dame. Presented before t h e Physical and Inorganic Division of t h e 132nd National Meeting of t h e American ChemiSeptember, 1957. cal Society, New York, N. Y., (2) (a) Sister M a r y Judith, R.S.M., M o u n t Saint Agnes College, Maryland. (b) Visiting professor, Faculty of Science, Tokyo University. (c) To whom correspondence concerning this article should be addressed: Dept. Chemistry, Florida S t a t e Univ., Tallahassee. (3) (a) D . N. Sen, S. hlizushima. C. Curran a n d J. V. Quagliauo, THIS JOURNAL, 77, 211 (1955); (b) D. h l . Sweeny, C. Curran and J. V. Quagliano, ibid., 77, 5508 (1955). (4) AI. L. Axorris and D. H. Biisch, lhrd , 78, 2178 (1956).
aspartic acid complexes5 of copper(I1) show relatively small shifts in the 0-C-0 vibrations from those observed for the simple ionic salts of these ligands. The infrared spectra of the oxalato complexes, of Fe(III), Cr(III), Al(II1) Pd(I1) and Cu(11),6 however, reveal that the oxygen-to-metal bond present in these compounds is approximately 50% covalent in character. The present investigation reports an infrared study of the complexes formed by these same metal ions with the bidentate malonate ion; the chelate malonato ligand is not rigid and planar like the oxalato group. The infrared absorption bands of malonic acid and its simple salts are assigned and the spectra of the malonato metal complexes are explained by comparison with these. Earlier work on malonate salts includes the infrared stud( 5 ) S. Kirschner. ibid.,78, 2372 (10.50). ( 6 ) h I . J. Schmelz, T. hfiyazawa. S. Mizushima, T. J . Lane anh J. V, Q u a p l i a n o , Spc
