Organometallics 1986,5, 514-518
514
OctadienybBridged 8irnetallic Complexes of Palladium as Intermediates in Telomerization Reactions of Butadiene Arno Behr,+ Godard v. Ilsemann,+Wilhelm Keim,*+Carl Kruger,t and Yi-Hung Tsayt Institute of Technical Chemistry and Petrochemistry. Technical University Aachen, D-5 100 Aachen, Federal Republic of Germany, and Max-Planck-Institut fur Kohlenforschung, D-4330 Mulheim a.d. Ruhr, Federal Republic of Germany ReC8iVed June 14, 1985
The synthesis and characterization of two bimetallic complexes 1 [(p-1-3-q:6-8-q-CgH12)(p-00CCH3)2Pd] and 6 [ ( P - ~ - ~ - ~ : ~ - ~ - ~ - C ~ H ~ ~ ) ( F & C are O Creported. H C O C FBoth ~ ) ~complexes P ~ ~ ] contain a bridging octadienyl chain and differ only in one having a palladium-palladium bond and the other possessing two isolated palladium atoms. Experiments are described converting 1 into 6, thus illustrating the ease of metal-metal bond splitting. With the addition of triisopropylphosphinethe 1:l and 1:2 adducts of 6 could be isolated. Complexes 1 and 6 were applied in the telomerization of butadiene with acetic acid yielding acetoxyoctadienes. Complex 1 is discussed as a potential intermediate in this telomerization. Further support rests on results obtained with deuterated butadiene. Complex 1 in the absence of acetic acid reacts with butadiene yielding complex 5 in which a Cl2 chain is bis q3-bondedto two palladium atoms. A reaction path for the oligomerization compared to the telomerization is discussed. Compound 6 has been characterized by an X-ray structure analysis (space group P2Jn with a = 4.6574 (4)A, b = 9.354 (1)A, c = 27.113 (2) A, @ = 94.573 (6)O,and 2 = 2).
Introduction Since the early days of homogeneous catalysis monometallic transition-metal complexes have been discussed as key intermediates in mechanistic reaction schemes. Here the mechanism to oligomerize butadiene by Wilke et al. or the hydroformylation reaction may serve as examples.' In recent years various multimetallic clusters of transition metals have been invoked as intermediates in catalytic reactiom2 However, it must be stated that unambiguous proof for a cluster catalysis is lacking so far. For many years we have been interested in the study of bimetallic complexes in olefin reaction^.^ We believe that it will be useful and easier prior to the understanding of multimetallic clusters to study bimetallic systems, which can be expected to be less complex. However, one must keep in mind that the number of metals or the size of the cluster can be important in determining catalytic properties and that the use of bimetallic compounds may not be generalized. For instance, in a recent paper it was reported that the size of the clusters affected reactions occurring on the surface of the multimetallic specie^.^ For the palladium-catalyzed telomerization of butadiene with acetic acid yielding acetoxyoctadienes we proposed the bimetallic mechanism outlined in Scheme I.3 In this paper, we want to describe the synthesis of 1, which has not been reported as yet. In addition, further experiments involving complex 1 dealing with bimetallic species will be presented. Experimental Section The 'H NMR spectra were recorded at 90 MHz on a Varian Model EM 390 and the '% N M R spectra at 200 MHz on a Bruker
Scheme I [Pd t C J H 1~OAc]
or
1
[Pdl OAcl2]
/ HOAc
OAc
60-mL glass autoclave a sample of 0.5 g (1.2 mmol) of bis[(q3ally1)palladium acetate] was dissolved in 30 mL of benzene. To the cooled, homogeneous solution were added 0.45g (7.5mmol) of acetic acid and 1.5 g (28mmol) of butadiene. After the yellow (1) (a) Jolly, P. W. In "Comprehensive Organometallic Chemistry";
Wilkinson, G., Ed.; Pergamon Press: Oxford, 1982: Vol. 8, p 671. (b) Model CXP 200. CDC13 was used as solvent. The shifts are Tkatchenko, I. In "Comprehensive Organometallic Chemistry";Wilkinexpressed as 6 values relative to Me4%. The IR spectra were son, G., Ed.; Pergamon Press: Oxford 1982: Vol. 8, p 101. performed on a Perkin-Elmer 577 using KJ3r pellets. Mass spectra (2) (a) Gates, B. C.; Lieto, J. ChemTech 1980,195,248. (b) Beach, D. were recorded on a Varian MAT 112 combined with the Varian L.; Kobylinski, T. P. J. Chem. SOC.Chem. Commun. 1980, 933. (c) Spectro System MAT 188 by using an ion source with a temHamilton, J. F.; Baetzold, R. C. Science (Washington,D.C.)1979,205, 1213. .(d) Jackson, S. D.; Wells, P. B.; Whyman, R.; Worthington, P. perature of 210 O C , a pressure of torr, and an ion energy of Catal. (London) 1981,4,75. (e) Muetterties, E.L.; Krause, M. J. Angew. 70 eV. Elemental analysis was carried out on an Elemental Chern. 1983,95,135. ( f ) Muetterties, E. L. CataE. Reu.-Sci. Eng. 1981, Analyzer Carlo Erba 1106. 23,69. (g) Whyman, R. Philos. Trans.R. SOC.London, Ser. A 1982,308, Preparation of (pl-3-r):6-8-r)-C8H12)(fi-OOCCH3)2Pd2 (1). 131. (h) Ugo, R.;Psaro, R. J.Mol. Catal. 1983,20, 53. (a) Starting from Bis[(~3-allyl)palladiumacetate)]. In a (3) (a) Keim, W. In "Transition Metals in Homogeneous Catalysis"; Institute of Technical Chemistry and Petrochemistry. t Max-Planck-Institut fur Kohlenforschung.
Schrauzer, G. N., Ed.; Marcel Dekker: New York, 1971; p 59. (b) Keim, W.; Behr, A.; Roper, M. In "Comprehensive Organometallic Chemistry"; Wilkinson, G., Ed.; Pergamon Press: Oxford, 1982 Vol. 8, p 311. (4) Chem. Eng. News 1985, Jan 21, 51.
0276-733318612305-0514$01.50/0 0 1986 American Chemical Society
Octadienyl-Bridged Bimetallic Complexes of Palladium Table I. 'H NMR Spectral Data of the Octadienyl Chain of Complex 1
signal 6
nH
a, d 3.1-3.9 4
b 2.4-2.9
C
e
4.8-5.5
1.8
2
2
4
Organometallics, Vol. 5, No. 3, 1986 515 Table 11. NMR Spectral Data of Complex 6
solution was stirred for 45 min at 45 "C, the volatile components were distilled off at torr. After addition of n-pentane, complex 1 precipitated as a white amorphous solid (0.23 g, 0.54 mmol; 45% yield). (b) Starting f r o m [ P ~ ( O A C ) ~ ] ,In . the same manner as 'H NMR Spectral Data described in a, 0.4 g (1.8 mmol) of [Pd(OAc),],, 3.0 g (54 mmol) H 6 nH multipl of butadiene, and 0.4 g (7.5 mmol) of acetic acid were reacted in a 4.1 2 d, J(a,c) = 6 Hz 30 mL of acetone for 13 h a t 50 "C forming complex 1 in a 42% b 3.05 2 d, J(b,c) = 12 Hz yield. The workup followed preparation under a. C 5.8-5.4 2 m The IR spectrum of complex 1 shows a weak absorption at 2920 d 3.9 2 m, J(c,d) = 12 Hz cm-' caused by the saturated C-H bond and strong absorptions e 2.05 4 m of the acetate groups a t 1575 and 1410 cm-'. The 'H NMR f 6.1 2 S spectrum (solvent CDC13) shows the signal of the methyl groups stemming from the acetate bridges (6 2.0; six protons) and four 13C NMR Spectral Data signals of the octadienyl chain (Table I). The allyl fragments C 6 multipl (coupled) are characterized by the two antiprotons H b at 2.4-2.9 ppm, the 1 56.5 t broad multiplet of the syn protons Ha and Hd at 3.1-3.9 ppm, and 2 89.8 d the two protons He at 4.8-5.5 ppm. I t is remarkable that the 3 79.6 d octadienyl chain is twisted in such a way that proton Hd appears 4 29.6 t in the range of the syn protons. In the mass spectrum the signal 5 112.4 d at m / e 108 confirms the presence of the octadienyl chain (C8H12). 6 109.4-123.0 9 Complex 1 has a decomposition point of 165 "C. Its elemental 7 175.4-176.1 9 analysis confirms the composition Pdz(OAc)zC8H12(Anal. Calcd C, 32.8; H , 4.13. Found: C, 33.4; H, 4.20.) Upon hydrogenation 65%) of white crystals of 8 with a melting point at 103 "C. Anal. quantitative yields of n-octane and palladium metal were formed. Reaction of Complex 1w i t h Butadiene Yielding Complex Calcd: C, 36.22; H , 3.94. Found: C, 36.58; H , 3.93. The IR 5. In a 60-mL glass autoclave 0.1 g (2.2 mmol) of complex 1 was spectrum contains nearly the same absorptions as the starting reacted with 2.5 g (46 mmol) of butadiene in 25 mL of benzene. complex 6,however, with a supplementary absorption at 2960 cm-' After being stirred for 6 h at 50 "C, the solution was evaporated. typical for C-H bonds in the isopropyl substituents. The 'H NMFt Upon addition of n-pentane, complex 5 precipitated (0.05 g, 0.1 spectrum shows the signals of the s3-allyl and the &allyl group mmol; 45% yield). The IR and 'H NMR spectra were identical (Table 111). The H' protons of the methylene group which is $-bonded to the palladium afford a characteristic doublet a t 2.8 with the literature data.s ppm. The two methine protons of the hexafluoroacetylacetonate Preparation of (p-1-3-q:6-8-~C8H12)(F3CCOCHCOCF3)2Pd2 ligands in complex 6 gave a single singlet at 6.1 ppm. In complex (6). In a 60-mL glass autoclave 0.5 g (0.95 mmol) of bis(hexafluoroacety1acetonate)palladium was dissolved in 5 mL of 8, the methine proton Hk, which is close to the phosphine, is methanol and reacted with 1.0 g (18.5 mmol) of butadiene a t 0 shifted to a higher field (singlet at 5.75 ppm), whereas proton Hj "C. The brownish orange solution darkened after a reaction time has furthermore a signal a t 6.1 ppm. This shift of the methine of 90 min and showed a deep red color after 2 h. After further proton agrees with data reported for Pd(Fsacac)2PR3.g being stirred for 2 h, the solution turned yellow and the white P r e p a r a t i o n of (p-1-q:2,3-q:6,7-q:8-q-C6Hl2)(F3CC0CHcomplex 6 began to precipitate. After evaporation of butadiene COCF3)(P-i-Pr3)2Pd2 (9). The reaction is almost identical with and the greater part of the methanol, n-pentane was added to the synthesis of complex 8: however, 0.084 g (0.52 mmol) of P-i-Pr3 get optimum precipitation. After filtration and drying a t loe2 was used. The pale yellow precipitate (0.098 g, 0.094 mmol: 37% torr, complex 6 was obtained in 61% yield (0.21 9). Recrystalyield) has a melting point of 120 "C. The elemental analysis lization was performed in a 2:l mixture of chloroform and nsupports the proposed structure. (Anal. Calcd C, 40.96; H, 5.34. pentane a t -5 "C, yielding needle-shaped crystals. Anal. Calcd: Found: C, 40.32; H, 5.32.) The 'H NMR spectrum (Table 111) C, 29.44; H, 1.92. Found: C, 29.44; H, 1.90. The IR spectrum shows a single singlet of the two shifted methine protons He a t consists absorptions due to the C-0 bonds at 1520 and 1670 cm-'. 5.68 ppm. Allylic protons (at about 4.0 and 3.0 ppm) are not The 'H NMR shows the syn protons Ha as a doublet a t 4.1 ppm observed, whereas the olefinic protons H b and HCappear a t 4.6 and Hd as a multiplet a t 3.9 ppm (Table 11). The anti protons or 5.5 ppm, respectively. Hb are shifted to a higher field at 3.05 ppm. This assignment is Reaction of Complex 1 w i t h Hexafluoroacetylacetone confirmed by decoupling of the methylene protons He at 2.05 ppm Yielding Complex 6. A 0.18-g (0.41-mmol) sample of complex which changes the multiplet a t 3.9 ppm into a doublet. The 1 was reacted a t room temperature with 0.17 g (0.90 mmol) of coupling constants of the signals of Ha, Hb, and H' are charachexafluoroacetylacetone in 10 mL of CHC13. After the solution teristic for q3-allylicsystems. The 13C NMR (Table 11)shows the was stirred for 16 h, the solvent was evaporated and the residue expected shifts and multiplicities, confirmed by further decoupling washed with n-pentane. Complex 6 is obtained in a 98% yield experiments. The mass spectrum contains the signal m / e 528, (0.3 g, 0.4 mmol). which corresponds t o t h e f r a g m e n t [ P d z ( C s H l z ) Experimental P e r f o r m a n c e of the Telomerization Reac(CF3COCHCOCF3)]+.Complex 6 decomposes a t 160 "C. tions. A 0.045-mmol sample of complex 1 or 6 and 0.09 mmol Preparation of (p-1-3-q:6,7-q:8-q-CsHl2) (F3CCOCHCOCF3)2 of tri-o-tolyl phosphite were dissolved in 10 mL of acetonitrile. ( P - i - P r 3 ) P d 2(8). A solution of 0.2 g (0.26 mmol) of complex 6 The solution was poured into a 60-mL glass autoclave equipped in 15 mL of tetrahydrofuran was reacted a t room temperature with a magnetic stirrer. Acetic acid (18 mmol) and butadiene (37 with 0.042 g (0.26 mmol) of triisopropylphosphine. After a reaction mmol) were added. After a reaction time of 16 h at a temperature time of 2.5 h the solvent of the brownish, homogeneous solution of 60 "C the autoclave was opened, the nonreacted butadiene was was distilled off at lo-' torr. The oily residue was crystallized evaporated, and the remaining acetic acid was washed out with in a 1:2 mixture of ether and n-pentane yielding 0.16 g (0.17 mmol; water. The organic layer was analyzed by gas chromatography
516 Organometallics, Vol. 5, No. 3, 1986
Behr et al.
Table 111.
________-__-
.~
' H NMR Spectra of Complexes 8 and 9 __________ --___ He
Hk
8 9
signal
h
a b
4.2-3.8 3.0 5.6-5.2 5 4.2-3.8
C
d e
f g h i J k 1 m
2.4-1.7 4.85-4.4 5.6-5.25 2.8 6.1 5.75 2.4-1.7 1.45-1.15
nH
multipl
signal
1 1 1 1
d d m d
a b
2
m
2 1 1 2 1 1
m m m d
e f
3
18
FJ
2.35-1.17 4.85-4.3 5.5-5.1 2.75 5.68 1.4-1.0 2.35-1.75
C
d 6
nH
multipl
4 2 2 4 2 36 6
m m m d s cl
m
S
s
m d
using a 50-m basic WG-11 capillary column and a temperature program of 100-230 "C (6 min isothermal, 8 OC/min).
Results and Discussion The telomerization of l,&dienes with a great variety of nucleophiles is known and has been reviewed r e ~ e n t l y . ~ For a better understanding of the reaction mechanism, we have studied the telomerization of acetic acid and butadiene in more detail. The chosen system can be regarded as representative for other nucleophiles and dienes. By reacting butadiene and acetic acid with bis[ (v3-allyl)palladium acetate] or palladium acetate, complex 1 (Scheme I) could be isolated out of the catalytically active reaction mixture. The X-ray structure6 showed a Pd-Pd distance of 2.9 A, which permits the discussion of a palladiumpalladium metal bond similar to that in bis[ (q3-allyl)palladium acetate].' However, in complex 1 palladium is formally in the oxidation state I11 which does not agree with the good NMR spectra, indicating that the compound is not paramagnetic. So far, the kind of bonding between the palladium atoms is not fully understood. Complex 1 can be considered as one key intermediate in the telomerization of butadiene with acetic acid. Complex 1 can exist in the q3-ailylform (Scheme I), the $-allyl form, and the ~ ~ ~ - ~ 7 ~form. - a l l yThe l VI-allylform originates from coordination of butadiene or phosphines as is discussed below. This coordination looses the CEchain, thus enabling an attack of the nucleophiles giving intermediate 2. The proton always bonds to carbon atom 6 as evidenced from the labeling experiments. The acetato group has the choice between carbon atoms 1 and 3, thus forming the two telomers observed, 1-acetoxyoctadiene and 3-acetoxyoctadiene. After the nucleophile acetic acid has been ( 5 ) Behr, A. Aspects Homogeneous Catal. 1984,5, 3. (6) Complex 1 was isolated first by W.K. during his time at Shell
Development, but the preparative method was not reported. W.K. is grateful to A. E. Smith for the X-ray data which also have not been published. (7) Churchill, M. R.; Mason, R. Nature (London) 1964, 204, 777.
added, incoming butadiene closes the catalytic circle via return to 1. Further support for this mechanism is gained from using deuterated butadiene depicted in eq 1. Complex 1 reacts OAc
CAc
-1 OAc
OAC
with C,D, in DOAc yielding C8H,,DOAc and complex 3 confirmed by MS and 'H NMR spectroscopy and gas chromatography. These results prove that the C8 chain present in complex 1 is also found in the reaction product C8H12DOAc.3 Interestingly, reaction of 1 with butadiene omitting acetic acid yielded complex 5 , which has been described by Medema and van Helden (Scheme II).* They also started from bis[ (~3-allyl)palladium acetate] and showed that in the first step complex 4 was formed by addition of butadiene to the allyl moiety. In a second step the two C7 fragments are displaced by three incoming molecules of butadiene, thus yielding 5. They proposed route b to account for the catalytic formation of linear CI2oligomers. In the presence of acetic acid, however, the reaction path alters giving CEH130Ac telomers via the interceptable complex 1 (route a). (8) (a) Medema, D.; van Helden, R.; Kohll, C. F. Inorg. Chim. Acta 1969,3,255. (b) Medema, D.; van Helden, R. R e d . Trau. Chim. Pays-Bas 1971, 90, 324. (9) Siedle, A. R.; Newmark, R. A,; Pignolet, L. H. J . Am. Chem. SOC. 1982, 104, 6584.
Organometallics, Vol. 5, No. 3, 1986 517
Octadienyl-Bridged Bimetallic Complexes of Palladium Scheme I1 Telomerization
path T e l o mers CgH130Ac +
HOAC
7 [HOPcl
f
Oligomers Oligomerization
n-Cl2H1.9
path
Table IV. X-ray Diffraction Data for CI8H14O4F12Pd2(6)" 0.11 X 0.28 X 0.48 mm crystal size crystal system monoclinic space group P2,/n (no. 14) a 4.6574 (4) A b 9.354 (1)A C 27.113 (2) A P 94.573 (6)' V 1177.4 A3
z
2
2.07 g cm-3 16.2 cm-' dMo) O.875,in - 1.286,, empirical absorptn correctn Enraf-Nonius CAD-4 diffractometer graphite-monochromated Mo radiatn X = 0.71069 A W-26 scan mode 21 "C T 1.0-34.0' 8 range 5105 (*h,+k,+l) measd reflctns unique reflctns 4768 3132 obsd reflctns ( I I 2u(n) 181 no. of varables 0.042 R 0.048 R, (w = l / a 2 (F,)) 2.3 goodness of fit 0.6 e A-3 residual electron density dcalcd
Structure solved by heavy-atom method, and hydrogen atom positions were located and kept fixed in the final refinement stages; all fluorine atoms were highly disordered and refined isotropically with partial occupancies.
In the present mechanism, bimetallic palladium complexes possessing palladium-palladium bonds are proposed as intermediates. It appeared of interest to prepare related bimetallic palladium complexes with isolated palladium atoms and to compare the catalytic properties of these complexes. The reaction of bis(hexafluoroacety1acetonato)palladium in methanol with butadiene gave complex 6, which as the X-ray structureloconfirms, lies on a crystallographic center (10)Computer programs used in this investigation are summarized in: Erker, G.; Dorf, U.; Engel, K.; Kruger, C.; Muller, G. Organometallics 1985, 4, 215.
Figure 1. Structure of complex 6. Table V. Selected Bond Lengths (A) and Angles (deg) for 6 Pd-01 Pd-02 Pd-C1 Pd-C2 Pd-C3 01-C5 02-C7 01-Pd-02 Cl-Pd-C2 Cl-Pd-C3 C2-Pd-C3 Pd-Ol-C5 Pd-02-C7 Cl-C2-C3
Bond Lengths 2.121 (3) Cl-C2 2.102 (3) C2-C3 2.099 (4) c3-c4 2.103 (4) c4-c4* 2.131 (4) C5-C6 1.261 ( 5 ) C6-C7 1.251 (5) Bond Angles 88.3 (1) Pd-C3-C4 38.7 (2) C2-C3-C4 68.7 (2) C4*-C4-C3 38.4 (1) 01-C5-C6 123.5 (3) C5-C6-C7 124.8 (3) 02-C7-C6 117.8 (4)
1.393 (6) 1.395 (5) 1.502 (6) 1.522 (5) 1.367 (7) 1.394 (7)
120.2 (3) 123.9 (3) 113.5 (3) 130.4 (4) 123.6 (4) 129.3 (4)
of inversion. Each P d atom is q3-bonded to one end of an octa-1,7-dienyl ligand. The molecular structure, together with the atomic numbering scheme, is depictured in Figure 1. Similar complexes of palladium and nickel with a bridging octadienyl chain have been described by Whitell
Organometallics, Vol. 5, No. 3, 1986
518
Behr et al.
Scheme I11
CHjOH
Table VI. Telomerization of Butadiene and Acetic Acid Using Bimetallic catalystsa selectivitv.b cat. yield, % A B C 1 97 63 8 29 6 87 65 9 26
-
I
"Catalyst: 0.045 mmol of complex phosphite. * OAc
\
A
6
7 -
Scheme IV
and Green.12 Details of the X-ray structural analysis are summarized in Table IV. Selected bond distances and angles are given in Table V. In the synthesis of complex 6, besides methanol, ethanol can also be used as a suitable solvent, whereas nonpolar solvents such as pentane or benzene fail to give 6. "In situ" IR measurements in methanol show a shift of the carbonyl frequency of Pd(F6acac), from 1605 to 1680 cm-l, which is in agreement with the formation of a palladium-carbon bond as shown in 7 (Scheme 111). The reaction of 6 with equimolar amounts of triisopropylphosphine gave complex 8, in which only one palladium metal is coordinated by the phosphine (Scheme IV). The 'H NMR spectrum confirms that v3-allyl and +allyl groups are present. When the same reaction is carried out with 2 equiv of P-i-Pr3 both v3-allyl groups convert to +allyl systems selectively yielding complex 9. The interconversion of complex 1, containing a palladium-palladium bond, into 6, with two isolated palladium atoms, could also be demonstrated by reacting 1 with hexafluoroacetylacetone. In this reaction the acetate bridges are displaced by the diketone and the Pd-Pd bond is broken (eq 2). OAc
\
0
OAc
//K \ Pd -Pd
2
+
2 hfacac
-
2 HOAc
*
-0
'Pd'
IZI
(11) (a) White, D. J. Chem. Res., Synop. 1977, 226. (b) White, D. J. Chem. Res., Miniprint 1977, 2401. (12) Green, M. L. H. J. Coord. Chem. 1972, 2, 43.
+ 0.09 mmol of tri-o-tolyl
OAc -4 /
OAc
B
C
As was pointed out above one aim of this investigation was directed toward whether bimetallic palladium complexes having palladium-palladium bonds, as in 1, compared to bimetallic complexes possessing two isolated palladium atoms, as in 6, show a different catalytic behavior. For this study both complexes l and 6 were reacted under identical conditions with butadiene and acetic acid. As shown in Table VI three telomers are obtained with similar conversions and selectivities. Unfortunately, this result does not allow conclusions to be drawn favoring palladium-palladium bonds in catalytic cycles. On the other hand, it cannot be ruled out either that a palladium-palladium bond may be formed under catalytic reaction conditions starting from 6 and, of course, vice versa. Bearing in mind that catalytically active intermediates can be formed in either thermodynamically or kinetically controlled reactions and, where several intermediates are involved, those having the highest reactivities would be present in the lowest concentrations, it will always be difficult to confirm a reaction mechanism from the isolated complexes. However, the isolated complexes can be regarded as good models for individual steps in catalytic cycles, thus advancing our understanding and proposing new reactions. The results obtained with deuterated butadiene certainly allow the discussion of a bimetallic mechanism vs. a monometallic one. Furthermore, this paper shows that the interconversion of a bimetallic species having a metal-metal bond into a bimetallic one exhibiting nonbonded metal atoms is rather easy.
Acknowledgment. We wish to thank the Bundesministerium fiir Forschung und Technologie for supporting this work. A generous gift of palladium dichloride by the Degussa AG (Hanau) is gratefully acknowledged. We also thank Dr. W. Meltzow for carrying out the GC work, W. Falter for the GC MS data and M. Sistig and B. Dederichs for the 'H and C NMR data.
'd
Registry No. 1, 99632-71-0;5 , 99632-72-1;6, 94698-82-5;8, 94715-89-6; 9, 99632-73-2; P ~ ~ ( O A C ) ~ ( T ~ - C12084-71-8; ~H,),, [Pd(OAc)z]3, 53189-26-7; Pd(F&COCHCOCF,)Z, 64916-48-9; CF3CCOCHZCOCF3, 1522-22-1; (E)-CHz=CH(CH,)BCH= CHCHZOAC,30460-73-2;(Z)-CH~=CH(CH~)~CH=CHCH~OAC, 30460-72-1; CHZ=CH(CHz),CH(OAc)CH=CH,,3491-26-7;trio-tolyl phosphite, 2622-08-4; butadiene, 106-99-0. Supplementary Material Available: Detailed information on the crystal structure determination of 6 including tables of final atomic positional parameters, final thermal parameters, and interatomic distances and angles and lists of observed and calculated structure factors (38 pages). Ordering information is given on any current masthead page.
