I720 Inorganic Chemistry, Vol. 14, No. 7 , 1975 relatively limited solubility in most other solvents. No extinction coefficients werc determined for the fluoro complex because of stability problems; this was not unexpected considering the relatively low stability of Cr(C0)sCl- in the same solvent. The higher stability of Cr(C0)SOH- was surprising. W(C0)sF- is reasonably stable in solution but follows the expected stability order 1 > Br > C1 > F. The spectra of the complexes (except for Cr(CO)jOH-) match the expected pattern in number of peaks and relative intensities.2j.26 W e are unable to account for the fact that while the spectra of the w(co)5X- (X = halide, OH ) complexes are all similar, the only band seen for C r ( C 0 ) 5 0 H - is at much higher energy than in the Cr(CO)5X- (X = halide) complexes. The limitation of the K-dibenzo-18-crown-6 cation in ultraviolet spectroscopy is illustrated by the hydroxo spectra. Acknowledgment. W e thank the Robert A. Welch Foundation (Grant A-509) for support of this research. Registry No. [Dibenzo-18-crown-6-K][W(CO)sOHj, 54964-71-5; [dibenro- 18-crown-6-K][ C r ( C 0 ) 5 0 H ] , 55000-28-7; [dibenzo-l8crown-6-KI [\V(C0)5F], 54964-72-6: dibenzo-l8-cro\w-6, 14187-32-7; Et4N[W(C0)5F], 54964-73-7; Et4T [Cr(CO)sF], 54964-74-8.
eferences and Notes This research constitutes partial fulfillment of the Ph.D degree requirements of J . L . C . C . J . Pedersen. J . An?. Cheni. Soc., 89, 7017 (1967). C . J . Pedersen, J . Ani. C h e m Soc., 92, 386 (1970). C . P. Liotta and H. P. Harris, J . Am. Chem. Soc., 96. 2250 (1974). D. J. S a m s and H . E. Simmons. J . Ani. C h e m Soc.. 96, 2 2 5 2 (1974). D. J. Sams and H. E. Simmons. J . Am. Chem. Soc., 94. 4024 (1972). W . Hciber, K. Englert, and K. Rieger, Z . Anorg Allg. Chem., 300, 295 (1959). W . Heiber. K. Englert, and K. Rieger, 2 . Anorg A/lg. C'hem.. 300, 304 (1959). V. G . Rlbano. G . Cidni, and Lf. Manasscro, J . Organomrr. Chem., 25, C 5 5 ( I 970). 4 . A . loganson, G . V . Loxshin, E. E. Kolobova, and K . N. Aniqimov, 1. Gen. Chem. L 5 S K (L'ngl. Trans/.),44, 20 (1974). M. 0 Johnson and N . Winterton. J . Chem Soc A , 51 1 (1970). 1. W. Stolr, G . R . Dobson. and R . K. Sheline. Inorg. Chrm., 2, 323 [ 1963). r. A. O'Donnell, K. A . Phillips, and A . B. Waugh. Inorg. Chem., 12, 1435 (1973). W . Douglas and J . K. Ruff, J . Organormi. Chmr., 65, 6 5 (1974). C . J. Pedersen. Org. Syntii., 52. 66 ( I 972). G. W . Gokel. D. J. C r a m , C . L. Llotta, H . P. Harris, and F. L. Cook, J . Org. Chem.. 39, 2445 (1974). J . K Ruff, Inorg. Cheni., 8, 86 (1969). J . K.Ruff, Inorg. Chern.. 7. 1 8 1 8 (1968). J. Solodar. Synth. Inorg. Met.-Org. Chem., 1. 141 (1971). A. Galliart and T. M.Brown, Synth. Inorg. Mer.Org. Chem., 2. 273 (1972). E. Linder and H . Behrens, Spertroch/m. Acm, Parr A, 23, 3025 (197 I) J . L. Cihonski and R . A. Levenson, unpublished results. K.J . H . Clark and B. C. Crosse. J . Chem. Soc. A . 224 (1969). E. W , Abel, I . S . Bulter, and .I.G . Reid, J . Cherri. Soc.. 2068 (1963). R. A . N . iMcLean, J . Chem. Soc.. Daiton T r n n s , 1568 (1974). M. Wrighton, Inorg. Chr/n., 13. 905 (1974).
Contribution from the Department of Inorganic and Structural Chemistry, The Lniversity, Leeds LS2 9JT. England
Reduction of p-Superoxo-his [pentaamminecobalt(III)] by Hexaammineruthenium(I1) and a Correlation of Kinetic Data for Two Series of Redox Reactions Timothy D. Hand, Michael R. Hyde, and A. Geoffrey Sqkes" Received October 29, 1974
AIC407541
The classification of electron-transfer reactions into either inner-sphere or outer-sphere categories is generally based upon the nature of primary reaction products,l including in some
Notes cases the identification of binuclear intermediates,' as well as information regarding the lability or inertness of metal ion reactants.3 In addition there are now several examples in which the less restrictive criteria of linear free energy correlations4 have been successful in providing a means of differentiating between These correlations have hitherto been established for reactions involving two reductants, for example, Cr*+ and V2+, with a common series of oxidants.8.9 Such correlations should also apply, but are less well established,l0 for the converse situation in which the reactions of two oxidant species with a common series of reductants are compared. Here we seek to test further this possibility and in doing so report data for the reduction of the p-superoxobis[pentaamminecobalt(III)] complex by Ru(NH3)6*+. Experimental Section Hexaammineruthenium(l1I) trichloride (Johnson Matthey Chemicals Ltd.) was purified as previously described] I (Amax 175.5 nm, e 472 M-1 cm-I) and reduced to hexaammineruthenium(I1), , A,( 275 nm, e 640 ,M-l cm I ) using a Jor.es reductor column, containing amalgamated zinc shot (IHopkin and Williams, Analar grade). under argon gas.12 The p-superoxo-bis [pentaamminecobalt(IIl)j complex was prepared by oxidation of p-peroxo-bis[pentaamminecobalt(I1I)] chloride in situ using ammonium peroxodisulfate, (NH4)2S20x. 13 The perchlorate salt was isolated and solutions ca. 0.01 M in 0.1 M HC104 were made u p immediately X(U,, 670 nm, t 890 M-I cm-I) and stored at -5" in a light-proof flask. The stoichiometry of the reaction was shown to be 1:1 by treating freshly generated Ru(NH3)$+ with an excess of the p-superoxo complex and measuring the absorbance change at 670 nm. The w-peroxo complex which is formed is unstable in acid solution.~4and when excess R u ( N H ~ ) ~is ~used. + further reaction occurs with the oxygen released.ll Absorbance changes corresponding to the reaction of the p-superoxo complex and the subsequent decomposition of the p-peroxo intermediate were monitored on a Durrum-Gibson stopped-flow spectrophotometer. Concentrations of Ru(NH3)6*+ pertaining to each run were checked immediately following stopped-flow runs by addition to an excess of p-superoxo complex and measuring the absorbance change at 670 nm.
Results and Discussion
The reaction was monitored at the 296-nm peak of the p-superoxo complex, t 2.45 X lo4 M-1 cm-1.15 At this wavelength two stages were observed, the first of which is assigned to (1). The Ru(NH3)6*+ was in at least eightfold R ~ ( f u " , ) , * ++ (NH,),CO-O,-CO(NH,)~~~ -+ Ru(NH,), 3t f (NH,), Co-O,-Co(NH,), 4+
(1)
excess and the ionic strength maintained at I = 0.1 M using LiC104-HC104. Plots of absorbance changes, log ( A- Am), against time were linear to at least 80% completion and yielded first-order rate constants. A threefold variation of [Ru("3)6*+], which was the maximum it was possible to achieve, indicated a first-order dependence on reductant and a rate law (2). Values of k at temperatures 1.5-15' are given in Table rate = ~ [ R U ( N H , ) , ~ [+p]- 0 2 - ] I. The two stages were less well separated at the higher temperatures, and as confirmation of our procedure and in order to ensure that a correct A m was being used, a full consecutive reaction treatment was carried out for a number of runs.16 Rate constants in Table I are seen to be independent of [H+]in the range 0.014.10 M . The range of concentrations of H+ and C104- as well as the range of temperatures over which reliable data could be obtained was restricted by the stability of Ru(NH3)6*+.17 Activation parameters, AH*= 0.8 f 0.5 kcal mol-1 and AS* = -25.8 f 1.8 cal K-1 mol-I, were obtained by a least-squares treatment (no weighting factor). The second stage of reaction corresponds to the decomposition of the primar,y product, the p-peroxo-bis[penta-
Inorganic Chemistry, Vol. 14, No. 7, 1975 1721
Notes
Table 11. Summary of Rate Constants (25") for the Reduction
Table I. Kinetic Data for the First Stage in the Reduction of p-Superoxo-bis [ pentaamminecobalt(III)] by Hexaamminerutlienium(I1) [ I = 0.1 M (LiClO,), h 296 nm]' 105 [RU(NH,),*+], Temp,"C [H+],M 1.5
5.0 10.0 15.0
0.01 0.01 0.01 0.05 0.08 0.05 0.08 0.01 0.05 0.10
M
106[pO,-],M
10m6k,M-' sec-'
4.19 5.43 5.56 11.85 6.56 6.22 11.62 4.49 6.46 5.32
2.87 6.90 5.73 6.90 6.90 6.90 6.15 2.87 6.90 6.15
2.71 (2) 2.55 (2) 2.65 (2)b 2.90 (2) 2.62 (3) 2.92 (3) 2.95 (2) 2.99 (2) 2.84 (2) 3.01 ( 2 )
of Hexaaquoiron(II1) ( k ~and ~ ) g-Superoxo-bis[pentaamminecobalt(III)]Complex ( k s ) i RU(NH,),~+ VZ+
EuZf cr2+ Fez'
Number of runs which have been averaged are indicated in parentheses [Cl-] = 0.01 M.
H+ H 0
lo3 103
3.7 x 9.6 x 3.0 X 2.3 x 5.8 x
106 104 lo4 103 lo-*
a, b c, d
d, e d , ~ g, h
First-order rate
a2CoZt + lo",*
(NH,),CO-O,-CO(NH,)~~~
105 104
This Reference 23; data extrapolated to 25", I = 0.1 M . w o r k ; I = 0.1 M . Reference 24. Reference 19. e D. W. Carlyle and J. H. Espenson, J. Am. Chem. SOC.,9 0 , 2 2 7 2 (1968). G. Dulz and N. Sutin,ibid., 8 6 , 8 2 9 (1964). J. Silverman and R. W. Dodson, J . Phys. Chern., 5 6 , 846 (1952); I = 0.55 M. R. Davies and A. G. Sykes, J. Chem. Foe. A , 2831 ( 1 9 6 8 ) ; I = 2.OM. The ionic strength ( I ) was 1.OM except as stated.
a
amminecobalt(III)] complex,lX as in (3).
4.3 x 1.8 x 6.8 X 2.3 x 4.0
+ 0, 0.01 M>
(3)
constants (kdec = 5.1 sec-I at l S O , [H+] = are dependent on [H+], but full details have not as yet been investigated. Reaction 3 is also observed as a second stage in the Cr2+, V2+, and Eu2+ reduction of the p-superoxo complex. 19 The rate constant for the reduction of the p-superoxo complex by R u ( N H ~ ) ~of~ 3.7 + X 106 M-l sec-l a t 25" (extrapolated value) and the low lability a t both the Ru(II)lo and Co(II1) centers ensure that the reaction is outer sphere. Data for a series of metal ion reductions of the p-superoxobis[pentaamminecobalt(III)] complex are now available, with rate constants ( k s ) a t 25" spanning several orders of mag~ )the reduction of hexanitude. Rate constants ( k ~ for aquoiron(II1) ([H+]-independent paths) are also available, Table 11. Although a plot of log k s against log k ~Figure ~ , 1, gives a satisfactory linear correlation (4), or for the aquo log k s = I .6 1 log kFe - 2.09
(4)
ions alone ( 5 ) , we have chosen to draw a line of slope 1.0 log ks = 1.75 log kFe - 2.39
(5 )
through the R u ( N H ~ ) ~ V2+, ~ + , and Eu2+ points only. Our reasons for adopting this approach are as follows. Data for the V2+ and E u ~ +reductions of seven common oxidants, including C0("3)6~+ and Co(NH3)5py3+ (which react by an outer-sphere mechanism) and the p-superoxo complex and Fe(H20)63+, give a good linear correlation (6).21 Similarly log kv= 1.01 log kEu
+ 0.51
(6)
rate constants for the y-superoxo and Fe(H20)63+ oxidants are in excellent agreement with the linear correlation for outer-sphere V2+ and Ru(NH3)62+ reductions as previously illustrated (eq 7).5 Data for outer-sphere reductions of V2+ log kv = 0.89 log k,,
- 0.95
(71
and Cr2+ also give a good correlation (8).22 From (6)-(8) log k v
zz
1.02 log k,,
+ 1.13
(8)
it can be concluded that four out of five of the p-superoxo reactions of Table I1 are outer sphere. Furthermore the Ru(NH3)62+ reduction of Fe(H20)63f is outer sphere since both reactants a r e insufficiently labile.23 Along with this assignment it has previously been concluded that the reaction of V2+ with Fe(H20)63+ is outer sphere.24 Now the slopes of (6)-(8) are close to unity, and it can therefore be concluded that the points for R u ( N H ~ ) ~V2+, ~ + , E u ~ +and , Cr2+ in Figure 1 should lie on or close to a line of slope unity, and certainly
Figure 1. Linear correlation of rate constants for the reduction of the p-superoxo-bis[pentaamminecobalt(III)]complex ( k s )and Fe(H20),'+ ( k F e ) ,by a common series of reductants.
not as in (4) or ( 5 ) . The line which we have drawn gives good correspondence for the points R u ( N H ~ ) ~ V2+, ~ + , and E u ~ + but is less satisfactory for Cr2+ and Fe2+. The deviation of almost one logarithmic unit for the Cr2+ point is perhaps marginal bearing in mind that NaC104 and not LiC104 was used to adjust the ionic strength for the Cr*+ reduction of Fe(H20)63+. The deviation from the line of slope unity is more extensive for the Fez+ point. If it can be assumed that outer-sphere Fez+ reductions should lie on the line of slope unity, then the deviation observed can be explained by too high a k~~ value. This may result from the Fez+ exchange with Fe(H20)63+ taking advantage of a more favorable inner-sphere pathway. Thus the evidence presented here suggests that the Fez+ reduction of Fe(H20)63+ ([H+]-independent pathway) may well proceed by inner-sphere electron transfer. It has previously been noted that for the Fe2+-Fe3+ exchange a mechanism involving H atom transfer with the generation of FeOH2+ and FeH303+ is unlikely on energetic grounds.25 There are at present no other examples in which it has been demonstrated that a water ligand bridges two metal ion reactants in an inner-sphere electron-transfer process. Previously Toppen and Linck26 have failed to detect a reaction path corresponding to the Cr2f reduction of Co(NH3)5H203+, and the reaction observed proceeds entirely via Co(NH3)50H2+.
Acknowledgment. T.D.H. and M.R.H. a r e grateful to the U.K. Science Research Council for the award of research studentships. W e thank Professor Gould for comments.
1722 Inorganic Chemistry, Vol. 14, No. 7 , 1975 Registry KO.Ru("3)6?+, References and Notes (1) H . Taube and H . Myers. J . Am. Chem. Soc.. 76. 2103 (1954). (2) (a) A. G. Sqkes and R.U. F. Thorneley. J. Chem. SOC.A , 232 (1970): (b) D. Seewaid, N.Sutin, and K.0. Watkins, J. A m . Chem. Soc.. 91. 7307 (1969); (c) W' G. Movius and R G . Linck, ;bid., 91. 5394 (1969). (3) ( a ) A . McAule) and J. Hill, Q. Rev., Cheni. Sor.. 23, 18-36 (1969); (b) K. Kustin and J . Swinehart. Prog. Inorg. Chem.. 13,101-158 (1970). (4) When the gradient is unity. such correlations a r e consistent with the Marcus cross reaction eqcation \ r i t h f = 1: R. A . Marcus. Annu. Rev. Phys. Chem., 15, 1 5 5 (1964),and refcrences therein. (5) M . R. Hyde, R. S . Taylor, and A . G . Sqkes, J . Chem Soc., Doiron Trans., 2730 (1973). (6) P.R.Guenther and R. G. Linck. J . A m Chem. SOC.,91,3769 (1969). (7) B. Grossman and A . Haim. J . A n i . Chem. SOC..93, 6490 (197l), (8) K. L.Scott and A. G . Sykes, J . Chem. Soc.. Dairoil Prafls.. 1832 (1972). (9) J C. Chen and E. S. Could. J . Arn Chem. Soc.. 95 (10) See data obtained by D. H . Huchital, K Sutin. and B.Warnqvist, Inorg. Chem., 6 , 838 (1967). and illustration and commenta in D. R Rosseinsky, Chem. R e v . , 72, 229 (19.72). ( 1 I ) J . R.Pladziewicz. T . J. Meqer. .IA. Broomhead. and H . Taube. Inorg. Chem., 12. 639 (1953). ( 1 2) An argon and not nitrogen atmosphere is essential: D. E. Harrison and H . Taube. J . Am Chem. Soc.. 89, 5706 (1967). (13) R.Davies. M. Mori. A. G . S!kes. and J A \Veil. Inorg S y n f h , 12. 197 (1970). (14) J . Simplicia and R . G . Wilkins, J . .4ri1.Chem. Soc.. 91, 1325 (19691. (15) A . G . Sykes and J . 4.Well, Prog. inorg. Chenz.. 13. 35 (1970). (16) For details see, for example. K. L. Scott. Li Green. and 4 . G. S q k e s , J . Chem. SOC.A. 3651 (l9il), (17) J . F. Endicott and H. Taubc. Inorg. Chem.. 4,437 (19653. (18) A . G . Sykes. Trans. F a r a d u j SOC..59. I325 (1963). (19) A . B. Hoffnien and H . Taube. (norg. Chern.. 7 . 1971 (1968) (20) J . F. Endicott a n d H . Taube, J . Ani. C h e w Soc., 86, 1686 (1964). (21) M. L Hbde. Ph.D. Thesis, Cniversiry o f Leedi, 1973. (22) Data for the Cr?+ and V2+ reductions of some 17 mononuclear. binuclear
(including the p-superoxo complex). and tetranuclear cobalt(lI1) compkxes belicved to bc outcr-sphere reactions give a linear plct of log kv against log kcT from which the fit log kv = (I .02 & 0.04) log kcr (1.73 0.1I) is obtained. K . L. Scott. personzl communication. T. J . Meqer and H . Taube. Inorg. Chern.. 7 . 2369 (1968). B. R.Baker. M.Orhanovic. and h .Sutin. J . A m .Chem. Soc.. 89, 722 (I 967). 4.G . Sykes, A d r . Inorg. Chenz. Radrochem.. 10. 1 5 s (1967). D.L. Toppen and R . G . Linck, Inorg. Chem.. 10. 2635 (1951).
+
(25) (26)
*
Contribution from the Department of Chemistry, Manchester Lniversity, Manchester M13 9PL, England
Inorganic Compounds Containing the Trifluoroacetate Group. 1V.I Preparation and Properties of Arsenic Tris(trifluoroacetate), As(OKCF3) 3, and Related Compounds C . Dabid Garner" and Barr) Hughes
Received October 2 4 . 1974
of MezAsCl and Ag02CCF3 and showed that, while the compound distilled a t its boiling point (136') under nitrogen, at 205' it decomposed giving some Me2AsCF3. This note reports a study of the preparation and properties of As(02CCF3)3 and an extension of this work to the corresponding P, Sb, and Bi compounds.
19052-44-9: ( N H ~ ) ? ~ ~ O K O ( N H ~ ) ~ ~prepared +, Me2As(02CCF3) by the reaction
12259-09-5.
(23) (24)
Notes
AIC40732F
Trifluoroacetato complexes of the group 5 elements which have been prepared previously included Bi(OKCF3)3, Na[Bi(OKCF3)4], and Na[As0(02CCF3)2] which were obtained by reaction of the corresponding oxide with trifluoroacetic anhydride.: Goel et al.3.4 have prepared R3Sb(OzCCF3)2 (where R = Me or Ph) and several other carboxylato derivatives by metathesis between R3SbX2 (X = halide) and Ag02CCF3 in MeOH ( K = Me) or C6H6 (R = Ph) solution and reported ir spectral, conductometric, and molecular weight data. The tris(carboxy1ato) complexes As(02CCHF2)$ and M(O2CH)$ ( M = Sb or Bi) have been synthesized, the former by heating Hg(CHF?C02)2 with As and the latter by refluxing M203 with HCO2H. However. attempts to prepare As(02CCH3)3 from AsC13 and C H X O z H (where si = 1 or produced a mixture of (CH~CO~)sAsC13-.u 2) derivatives which were not readily separable.' Cullen8 has
Experimental Section All manipulations were carried out under an atmosphere of dried nitrogen. Anhydrous CF3C02H (Koch-Light) and trifluoroacetic anhydride (Koch-Light) were used without further purification. Reagent grade AsCk and Pc13 were purified by distillation under reduced pressure and SbCI3 by sublimation under a dynamic vacuum at 65' (10-2 Torr); BiC13 was purified by the addition of excess SOC12 and refluxing for 2 hr, followed by the evaporation of excess SOC12. CHzCIz and CHC13 were distilled from CaH2, and T H F was distilled from N a wire, immediately prior to use. Ir spectra were recorded on Perkin-Zlmer 2 2 5 and 457 spectrometers calibrated with polystyrene film, and mass spectra were obtained on an AEI MS12 instrument using a 70-eV beam. ! H N M R spectra were measured on a Perkin-Elmer R12A instrument at 60 M H z using T M S as an internal standard, and 19F N M R spectra, on a Varian "4-100 instrument at 100 M H z using C6HsCF3 as an internal standard. Preparation of Arsenic Tris(trifluoroacetate), As(02CCF3)3. AsC13 (3.9 g, 21.5 mmol) was dissolved in CHzClz (50 ml), Ag02CCF39 (14.9 g. 67.5 mmol) was added, and the mixture was stirred for 4 hr at room temperature. The precipitate of AgCl was then filtered off and the bulk of the CHzClz distilled from the filtrate at 40' (760 Torr) to afford a viscous, pale yellow oil. Fractional distillation under reduced pressure afforded as the least volatile fraction a transparent, crystalline, extremely hygroscopic solid, mp 45.5-46.0°, in 70% yield, Anal. Calcd for C6F906AS: C , 17.4; F, 41.3; As, 18.1, Found: C , 17.1: F, 31.4; As, 18.1. The mass spectrum of the compound was obtained by dissolving a sample of CHzClz and injecting a portion of the solution through a serum cap into the warmed inlet of the mass spectrometer. Peaks were observed at the following m j e values (with relative intensities) and assigned as 396 ( 2 5 ) As4O6+, 301 (30) As(02CCF3)z+. 300 (10) 4s4+. 220 (IO) AsOz(02CCF;)+. 207 (25) AsF(OzCCF3)+. 188 (50) As(02CCF3)+. in addition to peaks corresponding to further fragmentation products, including mie 91 (100) AsO+. Ir spectra were recorded for a sample sublimed as a thin film onto a NaCl window cooled to ca. -196' and contained in an ir gas cell (Table I) and also for samples dissolved in CH2C12 and CS2 at room temperature. The 19F Y M R spectrum of the compound dissolved in CHCI3 consisted of a single resonance 76.8 ppm upfield of CFC13, within the range 74-79 ppm upfield of C F C h typicall: of trifluoroacetate compounds. Preparation of Trikinylarsonium Trifluoroacetate, [ (H2C= CH)3AsH]O:CCF3. The reaction between (H2C=CH)3As and CF3C02H was investigated as an alternative synthetic route to As(OKCF?)3. (H:C=CH)3As (2.4 g) was prepared10 by the reaction of AsCl? and (HzC=CH)MgBr in T H F and was then added to a mixture of CF3C02H (10 mi) and (CF3CO)>O (1 mi); this solution was refluxed for 3 hr. The excess solvent was then evaporated at ca. 7 2 O (760 Torr), and the residue was extracted with CHzClz and filtered before distillation of solvent at ca. 40" (760 Torr). On allowing the resulting viscous solution to stand at -10" for 2 hr, large platelike crystals were deposited. These crystals were filtered and washed with pcntane; traces of solvent were removed by pumping (10-3 Torr) at room temperature: yield 2.45 g, 65% based on (H2C=CH)?As; mp 154-156' dec. Anal. Calcd for CsHioAsF3Oz: C , 35.5: H , 3.7: As, 27.8. Found: C, 35.2: H . 3.5; .4s, 27.6. The mass spectrum was recorded at 100" and contained peaks at m / e 157, 156, 129. 102, and 75, corresponding to the fragments ( H K = C H ) 3 A s H + and (HPZ=CH)~AS+ (where n = 3, 2, 1. or 0). respectively, and at m / e 113, 97, 94, and 69 corresponding to C F C 0 2 + , CF?CO+, C F z C O P , and CF3+ fragments, respectively. The 'H N M R spectrum of [ ( H ? C = C H ) ~ A S H ] ( C F ~ C Oin~CDC13 ) solution consisted of a singlet at T 6.9, assigned to the A - H hydrogen atom, and 12 resolved peaks centered at T 3.5 which resemble those obtained for (HzC=CH)4Sn and (HK=CH)2Sn(02CCF3)2.I1 Preparation of Arsenic Tris(trifluoroacetate)-2,2'-Bipyridyl, As(O~CCF~);.K~CIO .4s(OzCCF3)3 H~. (2.07 g, 5 mmol) was dissolved in CHC13 (10 ml) and a solution of 2,2'-bipyridyl (0.78 g, 5 mmol) in CHCI3 ( 5 ml) w a s added; the resulting solution a a s stirred for 0.5
