2574
PAULM. KUZNESOF AND WILLIAM L.
Iizorgunic Clzenzistvy
JOLLY
COSTRIBUTIOK FROM THE DEPARTMENT OF CHEXISTRY OF THE UNIVERSITY OF CALIFORSIAA N D T H E IPU'ORGANC MATERIALS RESEARCH DIVISIONOF THE LAWRENCE RADIATION LABORATORY, BERKELEY, CALIFORXIA 94720
Potassium 2-Germaacetate, an Analog of Potassium Acetate BY PAUL M. KUZXESOF A N D WILLIAM L. JOLLY
Recehed illay 23, 1968 Potassium germyl reacts with carbon dioxide to give a salt, KGeHSCO2. The infrared and ultraviolet spectra and the products of hydrolysis suggest a structure for the anion analogous to that of the acetate ion. Aqueous sdutions of KGeH3COz undergo very slow hydrolysis a t room temperature; a t 85" hydrolysis is essentially complete in 2 days: GeH3C02H20 + GeHp HCOJ-. Acidification of aqueous KGeH3C02 yields a solution of 2-germaacetic acid (pK = 3 . 5 ) which undergoes decomposition to give a quantitative yield of carbon monoxide and nonstoichiometric amounts of germane and an orange solid containing germanium and hydrogen. The effects of the vacant 4d, orbital of germanium on the physical and chemical properties of 2-germaacetate are discussed.
+
+
Introduction Results and Discussion I t has previously been shown1 that potassium germyl Spectral Studies.-Potassium germyl in 1,2-dimethoxyethane reacts quantitatively with carbon reacts with diborane to form the adduct K+H3GeBH3-. In this investigation we have found that potassium dioxide to produce a white solid, KGeH3C02: KGeH3 germyl reacts with carbon dioxide to form the adCOZ+ KGeH3C02. At present, our best evidence duct K+H3GeC02-, which we believe to be structurally that the GeH3C02- ion has a structure like that of the analogous to potassium acetate. By comparing the acetate ion is the infrared spectrum shown in Figure 1. physical and chemical properties of the H3GeC02- ion The absorptions a t 1540 and 1325 cm-' are characterwith those of the acetate ion, it is possible to learn istic of the carboxylate group;l0 for sodium acetate, the effect of replacing a carbon atom adjacent to a CO2- vibrations appear a t 1560 and 1410 cm-'. The n-bonded system with a germanium atom. In preband a t 2060 cm-' is characteristic of Ge-H stretching vious comparisons of this type (involving organo-ain germyl compounds. l 1 - I 3 Absorptions a t 873, 825, germyl and -a-silyl ketones2s3 and carboxylic acids4) and 800 cm-I are probably GeH3 deformation modes.14 the interpretations have been complicated by the The 678-cm-l band may reasonably be assigned to a presence of organic groups attached to the germanium GeH3 rocking vibration on the basis of assignments for atom. the 670- and 664-cm-' absorptions in digermoxaneI5 I t appears likely that a wide variety of germyl derivaand fluorogermane, respectively. The last band a t tives can be conveniently prepared by the reaction of 557 cm-1 occurs in the region (600-520 cm-l) assigned potassium germyl with Lewis acids and with compounds to asymmetric Ge-C stretching vibrations. containing displaceable electronegative groups (such The bathochromic shift of the infrared COX- vibrations on going from CH3C02- to GeH3CO2- may be as alkyl halides5). Potassium germyl can be prepared by the reaction of germane with potassium metal explained in terms of pT-d, back-bonding from the in liquid ammonia6!' (where considerable side reaction carboxyl group into the vacant d orbitals of germanium. Such back-bonding would be expected to to form Ge(NH2)2occurs), in dimethoxyethane1*8(where the reaction is slow because of the low solubility reduce the double-bond character of the C0,- group, of the potassium) , or in hexamethylpho~phoryltriamide~ resulting in a frequency shift to lower energy. In this (where, because of the low volatility of the solvent, manner, Brook, et aZ.,'*have interpreted the relative carbonyl stretching frequencies for a series of organosoluble nonvolatile products from subsequent reactions are difficult t o isolate). We have found that potassium substituted a-germyl, a-silyl, and a-methyl ketones. However, it should be pointed out that such interpregermyl is most conveniently prepared by the reaction tations have been criticized. Thus, Yates and Agoof germane with a slurry of potassium hydroxide in liniIg have discussed the data of Brook, et al., in terms a nonhydroxylic solvent, although the reaction with of an inductive effect in order to obtain a correlation potassium in dimethoxyethane is preferred when i t is desired to isolate quantitatively a given quantity of (10) J. L. Bellamy, "The Infrared Spectra of Complex Molecules," 2nd potassium germyl. ed, Methuen and Co., Ltd., London, 1957, p 174.
+
(1) D. S. Rustad and W-.L. Jolly, Inoig. Ckein., 7, 213 (1968). (2) R. W. Harrison and J. Trotter, J . Chem. Soc., A , 258 (19681, and references therein. (3) D. A. Sicholson and A. L. Allred, Inoig. Chem., 4, 1747 (19651, and references therein. (4) 0. W. Steward, H. W. Irwin, R. A. Gartska, and J. 0. Frohlinger, Abstracts, 154th National Meeting of the American Chemical Society, Chicago, Ill., Sept. 1967, No. 0115. (5) D. S. Rustad, T. Birchall, and W. L. Jolly, Inovg. S y n . , 11, 128 (1968). (6) G. K . Teal and C. A. Kraus, J . A m . Chem. Soc., 72, 4706 (1930). (7) D. S. Rustad and W. L. Jolly, Inorg. Ckem., 6,1986 (1967). (8) W. R. Bornhorst and >I. A. Ring, ibid., 7 , 1009 (1968). (9) S. Cradock, G. A. Gibbon, and C. H. Van Dyke, ibid., 6 , 1751 (1967).
(11) D. A. Dows and R. PI. Hexter, J . Ckem. P k y s . , 34, 1029 (1956). (12) J. E. Drake and W. L. Jolly, J . Ckenz. Soc., 2807 (1962). (13) R. C. Lord and C. M. Steese, J . Ckem. P k y s . , 2 2 , 542 (1954). (14) GeHs deformations (excluding rocking modes) appear between 1300 and 750 cm-1: E. A. V. Ebsworth in "Infared Spectroscopy and Molecular Structure," M. Davies, E d . , Elsevier Publishing Co., New York, N. Y., 1963, p 314. (15) T. D. Goldfarb and S. Sujishi, J . Am. Chem. Soc., 86, 1679 (1964). (16) J. E. Griffiths, T. N.Srivastava, and M. Onyszchuk, C a n . J . Ckein., 40, 579 (1962). ( l i ) F. Glockling, Q z i a ~ l .Keu. (London), 20, 45 (l!lOfl). (18) A, G. Brook, &I. A. Quigley, G . J. Peddle, N-.V. Schwartz, and C.X I . Warner, J . Am. Chem. Soc., 82, 5102 (1960). (19) K. Yates and F. Agolini, Can. J . Chem., 44, 222Y (1966).
Vol. 7, No. 12, December 1968
POTASSIUM
Crn“. 2200 2000 1500
1250 900
800
700
2-GERMAACETATE 2576
ducible amounts of germane and an insoluble orange solid containing both germanium and hydrogen
650600
H+
GeHaCOzH --f CO
+ xGeH6 + solid
The value of x ranges from 0.1 to 0.6. It seems reasonable to compare this reaction with acid-catalyzed decarbonylations of organic carboxylic acids. Possibly a mechanism of the following type is involved. GeHaCO2H
0
+ H + -+
[GeH&02H2+]
+ CO + HzO + HnO --+ xGeH4 + solid
[GeHaCO2H2+]---f [GeH3+] Figure 1.-The
infrared spectrum of a Nujol mull of KGeHsC02. n’ujol absorptions have been deleted.
with their ketone basicity measurements. And from a recent X-ray determination of the structure of triphenylgermyl methyl ketone2 it has been inferred that the extent of back-r-bonding in the solid is insignificant. The electronic spectrum of the 2-germaacetate ion consists of a band a t 239 mp ( E
