COMMUNICATIONS
[3] a) G. W. Parshall, S. D. Ittel, Homogeneous Catalysis: The Application
and Chemistry of Catalysis by Soluble Transition Metal Complexes
2nd ed., Wiley, New York, 1992; b) M. Beller, B. Cornils,
C. D. Frohning, C. W. Kohlpaintner, J. Mol. Catal. A 1995, 104(1),
17 ± 85.
[4] I. Tkatchenko in Comprehensive Organometallic Chemistry, Vol. 8
(Eds.: G. Wilkinson, F. G. A. Stone, E. W. Abel), Pergamon, Oxford,
1982, pp. 101.
process that avoids hydroformylation conditions. Catalyst
deactivation pathways that result in decarbonylation products
have been identified. In the presence of other olefins, transfer
formylation was observed, which provides in principle a
general method for the introduction of a formyl group into an
olefinic substrate.
[5] R. L. Pruett, Ann. N. Y. Acad. Sci. 1977, 195, 239.
Experimental Section
[6] L. M. Petrovich, C. P. Casey, J. Am. Chem. Soc. 1995, 117, 6007.
[7] a) L. A. Van der Veen, P. C. J. Kamer, P. W. N. M. Van Leeuwen,
Angew. Chem. 1999, 111, 349 ± 351; Angew. Chem. Int. Ed. 1999, 38,
336; b) B. Breit, Eur. J. Org. Chem. 1998, 1123 ± 1134; c) K. Nozaki, H.
Takaya, T. Hiyama, Top. Catal. 1998, 4, 175.
[8] C. P. Casey, E. L. Paulsen, E. W. Beuttenmueller, B. R. Proft, B. A.
Matter, D. R. Powell, J. Am. Chem. Soc. 1999, 121, 63.
[9] The C H bond activation of aldehydes has been described and was
applied until recently predominantly in aldehyde decarbonylation
reactions to generate a metal ± CO complex and the parent alkane.
H. M. Colquhoun, D. J. Thomson, M. V. Twigg, Carbonylation: Direct
Synthesis of Carbonyl Compounds, Plenum, New York, 1991.
[10] J. Tsuji, K. Ohno, Synthesis 1969, 157.
All operations were carried out under an Ar atmosphere. All solvents used
were degassed and purified following standard methods.
2: [(C5Me5RhCl2)2] (0.2 g, 6.5 Â 10 4 mol) was stirred with zinc (0.45 g,
6.5 Â 10 3 mol) in THF (15 mL) for 24 h while a slow flow of propene was
passed over the reaction mixture. The residual zinc was filtered from the
homogeneous yellow mixture, which was evaporated, and extracted into
pentane. Removal of the solvent generated a yellow solid. Recrystallization
from acetone yielded complex 2a as yellow crystalline material (one
isomer) which was used for the structure determination (Figure 1).
1H NMR (400 MHz, [D6]acetone, 208C): d 1.51, 1.56, 1.62 (3 Â s, 3 Â
15H, 3 Â C5Me5), 0.95, 1.41, 1.45, 1.59 (4 Â d, 4 Â 3H, Me), olefinic CH
overlapping, the 4th C5Me5 resonance is obscured; 13C{1H} (100 MHz,
[D6]acetone, 208C): 2a: d 9.40, 97.0 (d, 3.8 Hz, C5Me5), 60.0, 45.7 (d,
5.6 Hz), 21.1 (Me); 2c: 10.1, 97.5 (d, 3.8 Hz), 52.6, 47.8 (d, 14 Hz), 21.3 (Me);
2b and 2d: 9.3, 96.9 (d, C5Me5 and 8.7, 96.5 (d, C5Me5), 56.0, 54.5, 54.1, 52.2,
50.1, 47.4, 46.6, 44.6 (d), 21.8, 21.4, 19.5, 17.1 (Me). Elemental analysis:
calcd: C 59.63, H 8.44; found: C 59.90, H 8.62.
[11] J. Tsuji, K. Ohno, J. Am. Chem. Soc. 1968, 90, 99.
[12] M. Brookhart, C. P. Lenges, P. S. White, J. Am. Chem. Soc. 1998, 120,
6965.
[13] C. P. Lenges, M. Brookhart, J. Am. Chem. Soc. 1997, 119, 3165.
[14] C.-H. Jun, J.-B. Hong, D.-Y. Lee, Synlett 1999, 1.
[15] B. Bosnich, Acc. Chem. Res. 1998, 31, 667.
[16] In some Ru-catalyzed hydroacylation reactions the transfer formyla-
tion of benzaldehyde and cyclohexene to benzene and cyclohexane-
carbaldehyde has been observed. T. Kondo, M. Akazome, Y. Tsuij, Y.
Watanabe, J. Org. Chem. 1990, 55, 1286.
[17] Complex 2 has been prepared previously by Müller and co-workers in
a reaction of [(C5Me5RhCl2)2] with iPrMgBr. J. Müller, H.-O. Stühler,
W. Goll, Chem. Ber. 1975, 108, 1074.
[18] The analogous [C5H5Rh] complex has been reported: L. P. Seiwell,
Inorg. Chem. 1976, 15, 2560.
[19] The formation of isomers was also observed in analogous rhodium
methylacrylate complexes. E. Hauptman, S. Sabo-Etienne, P. S. White,
M. Brookhart, J. M. Garner, P. J. Fagan, J. C. Calabrese, J. Am. Chem.
Soc. 1994, 116, 8038.
Structural data for 2a: crystals obtained from acetone; C16H27Rh, Mr
322.29, monoclinic, space group P21/n, Z 4, a 14.2482(7),
b 7.1385(4), c 15.7584(8) , b 108.8420(10)8, V 1516.91(14) 3,
1
1calcd 1.411 gcm
,
T 1108C, 2qmax 508, MoKa radiation (l
0.71073 ), 7807 reflections were measured; 2672 unique reflections were
obtained, and 2100 of these with I > 3.0s(I) were used in the refinement,
data were collected on a Siemens SMART diffractometer using the omega
scan method. For significant reflections merging R 0.035, residuals: RF
0.044, Rw 0.047 (significant reflections), GOF: 2.54. ± Crystallographic
data (excluding structure factors) for the structures reported in this paper
have been deposited with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC-136183. Copies of the data can be
obtained free of charge on application to CCDC, 12 Union Road,
Cambridge CB21EZ, UK (fax: (44)1223-336-033; e-mail: deposit@
ccdc.cam.ac.uk).
[20] Maitlis and co-workers have prepared similar complexes in a reaction
of [C5Me5Rh(dmso)Me2] with aldehydes. The complex [C5Me5Rh-
1
(CO)MeEt] (nÄCO 1990 cm
) was generated in a reaction with
3: A solution of [C5Me5Rh(C2H3Me)2] (0.1 g, 3.1 Â 10 4 mol) in benzene
(10 mL) was treated with 10 equiv of n-butanal (0.22 g) and heated for one
hour at 508C. All volatiles were removed and complex 3 was isolated as a
yellow oil. Complex 3 decomposes as the oil or in solution over several
hours at 208C; attempts to crystallize 3 from acetone were not successful.
1H NMR (400 MHz, [D6]acetone, 208C): d 1.74 (s, 15H, C5Me5), 0.89 (t,
7.8 Hz, 6H, CH3), 1.21 (m, 4H, CH2), 1.48 (m, 4H, CH2); 13C{1H} NMR
(100 Mhz, [D6]acetone, 208C): d 9.0 (C5Me5), 101.9 (C5Me5), 24.2 (d,
propionaldehyde, but was too unstable for isolation. P. M. Maitlis,
G. J. Sunley, J. M. Kisenyi, M. Gomez, J. Organomet. Chem. 1985, 296,
197.
[21] Thermolysis of 3 in [D6]benzene at 508C yields 4 (ꢀ85%) and other
unassigned organometallic complexes in addition to n-butanal,
propene, and propane.
[22] A. Nutton, P. M. Maitlis, J. Organomet. Chem. 1979, 166, C21.
[23] a) Catalytic hydroacylation of aromatic aldehydes is observed using
complexes of type 2 at 1008C with 5 turnovers per hour; alkyl
aldehydes are not converted under these conditions: C. P. Lenges, M.
Brookhart, unpublished results; b) the presence of acid impurities in
the reaction mixture can terminate catalysis and is more significant in
reactions with reduced catalyst loading.
[24] a) Based on the heats of formation of n- and iso-butyraldehydes and
calculated entropies of formation, the thermodynamic ratio of these
aldehydes should be about 1:1. See K. B. Wiberg, L. S. Crocker, K. M.
Morgan, J. Am. Chem. Soc. 1991, 113, 3447; b) during catalytic
hydroacylation reactions using cobalt analogues only the formation of
the Co-n-alkyl intermediates was observed in the reaction of the
isomeric butanals, which is in line with the results observed here for 3
versus 3'. The formation of the branched alkyl intermediate was
suggested by labeling studies and the formation of isomeric product
mixtures but not directly observed; see reference [12].
25.8 Hz, RhCH2), 19.7 (d, 2.6 Hz, CH2), 29.4 (s, CH3), 196.0 (d, 83.2 Hz,
1
RhCO); IR (toluene): nÄCO 1979 cm
.
6: Complex 6 was prepared in an analogous manner to complex 2 and
isolated as an orange solid after recrystallization from acetone. NMR
analysis shows the formation of one major isomer (70%) and two minor
isomers based on olefin coordination as discussed for 2. 1H NMR
(400 MHz, [D6]benzene, 208C): d 1.43 (s, 15H, C5Me5), 2.10 (dd, 16.0,
2 Hz, 2H), 2.55 (dd, 16.0, 2 Hz, 2H), 3.83 (ddd, 16.0, 10, 2 Hz, 2H), 6.38 (m,
2H, Ar), 6.89 ± 7.05 (m, 2H, Ar), 7.02 ± 7.23 (m, 6H, Ar).
Received: June 30, 1999 [Z13656IE]
German version: Angew. Chem. 1999, 111, 3746 ± 3750
Keywords: aldehydes ´ C H activation ´ hydroformylations
´ isomerizations ´ rhodium
[25] In addition, propene, and the isomeric butanals are observed in the
reaction mixture.
[26] The chloro-bridged complex [(C5Me4CF3)RhCl2]2 was prepared as the
precursor following the literature procedure. P. G. Gassman, J. W.
Mickelson, J. R. Sowa, Jr., J. Am. Chem. Soc. 1992, 114, 6942. Using
[1] O. Roelen (Ruhrchemie A. G.), German Patent 849548, 1938.
[2] G. Wilkinson, J. A. Osborn, D. J. Evans, J. Chem. Soc. A 1968, 3133.
3536
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