Pentacarbonylphenylmanganese

(CO)5MnPh

[13985-77-8]  · C11H5MnO5  · Pentacarbonylphenylmanganese  · (MW 272.10)

(undergoes migratory insertion of CO into metal-aryl bonds;1 can acylate alkynes and alkenes2)

Physical Data: white crystals; mp 51-52 °C.

Solubility: sol organic solvents.

Form Supplied in: not commercially available.

Analysis of Reagent Purity: IR (CCl4, cm-1) 2115 (m), 2019 (vs), 1997 (s);2 (KBr, cm-1) 2126 (w), 2058 (m), 2015 (vs).3

Preparative Methods: decarbonylation of (CO)5MnCOPh by heating under N2 atmosphere (eq 1), either in situ or after isolation of the acyl complex.2-5 The complex is also available in 93% yield from irradiation (254 nm) of Decacarbonyldimanganese and Diphenylmercury in cyclohexane/THF solvent.6

Purification: sublimation (25-40 °C/0.1 mmHg); recrystallization from pentane, hexane, or light petroleum ether; column chromatography on silica gel with hexane. Complexes bearing electron-donating substituents on the aromatic ring (p-Me, p-OMe) are apparently less stable to chromatography than the parent or electron-deficient (p-Cl) compounds.6

Handling, Storage, and Precautions: may be handled in air, but decomposes upon prolonged exposure to oxygen. Indefinitely stable when stored as a solid in the absence of air at -20 °C. While no information concerning the toxicity of this compound is available, one should assume that metal carbonyls are highly toxic; since this is a volatile solid (vapor pressure ~2 mmHg at 20 °C), extra care should be taken to avoid exposure. Use in a fume hood.

Migratory Insertion Reactions: Aryl Carbonylation.

Much of the synthetic chemistry of pentacarbonylmanganese aryl compounds derives from the trapping of the coordinatively unsaturated acyl intermediate (CO)4Mn(COR) produced from migratory insertion. In the absence of added ligand the pentacarbonyl aryl complex is favored, but the addition of simple donor ligands such as phosphine or phosphite provides good yields of cis-substituted acyl complexes (eq 2).1,4,7 The migratory insertion step is assisted by polar solvents.8 In addition to the processes outlined below, the following miscellaneous trapping agents have been reported (product type in parentheses): Ph2PSiMe3 (metallacyclic a-silyloxymanganese phosphide complex);9,10 chiral and achiral germyl anions, R3GeLi, or Mn(CO)5- (cis-tetracarbonylacyl complexes bearing Mn-Ge or Mn-Mn bonds, leading to Fischer carbene compounds).11-13 Substitution of a cis-CO ligand without aryl migratory insertion may be achieved by the addition of N-oxides.7

Acylation of Alkenes and Alkynes: Sequential CO/Alkene or CO/Alkyne Insertion.

The interception of coordinatively unsaturated aromatic acyl intermediates with alkenes has been reported for a few cases. Dicyclopentadiene affords b-benzoyl alkyl complexes stabilized by intramolecular coordination of the ketone oxygen.14 The use of dienes gives rise to h3-ketoallyl products (eq 3).15 Under photolytic conditions, CO is ejected and alkene insertion directly into the Mn-Ph bond is observed (eq 4).16 Interestingly, cycloheptatrienes afford noncarbonylated h5-pentadienyl products from a similar alkene insertion process upon heating.17

Alkynes are also acylated by (CO)5Mn-aryl complexes, although this reaction has not been used as frequently as the analogous reactions of (CO)5Mn-alkyls (eq 5).2,18,19 Demetalation is accomplished under mild acidic (replacing Mn with H) or reductive conditions.2,19,20

Cyclometalation.

Aromatic imines and ketones, when treated with (CO)5MnPh, are metalated ortho to the directing group (see Pentacarbonylmethylmanganese).21,22 The same type of cyclometalated ketones are available from (CO)5Mn-R and Ph2Hg (R = alkyl).6 The products are stable in air and may be purified by column chromatography.

Protonolysis.

Arenes may be liberated from pentacarbonylmanganese alkyls by protonation with strong acids.23


1. Axe, F. U.; Marynick, D. S. JACS 1988, 110, 3728.
2. Dowler, M. E.; Le, T. X.; DeShong, P.; Von Philipsborn, W.; Vöhler, M.; Rentsch, D. T 1993, 49, 5673.
3. Beck, W.; Hieber, W.; Tengler, H. CB 1961, 94, 862.
4. Booth, B. L.; Green, M.; Haszeldine, R. N.; Woffenden, N. P. JCS(A) 1969, 920. Products resulting from multiple substitution are formed under certain reaction conditions.
5. Coffield, T. H.; Kozikowski, J.; Closson, R. D. JOC 1957, 22, 598.
6. Haupt, H. J.; Neumann, F.; Schwab, B.; Voigt, G. Z. Anorg. Allg. Chem. 1980, 471, 175.
7. Blumer, D. J.; Barnett, K. W.; Brown, T. L. JOM 1979, 173, 71.
8. Bent, T. L.; Cotton, J. D. OM 1991, 10, 3156.
9. Vaughn, G. D.; Krein, K. A.; Gladysz, J. A. OM 1986, 5, 936.
10. Vaughn, G. D.; Krein, K. A.; Gladysz, J. A. AG(E) 1984, 23, 245.
11. Carré, F.; Cerveau, G.; Colomer, E.; Corriu, R. J. P. JOM 1982, 229, 257.
12. Dean, W. K.; Graham, W. A. G. JOM 1976, 120, 73.
13. Casey, C. P.; Cyr, C. R. JOM 1973, 57, C69.
14. Booth, B. L.; Gardner, M.; Haszeldine, R. N. JCS(D) 1975, 1856.
15. Green, M.; Hancock, R. I. JCS(A) 1968, 109.
16. Lipps, W.; Kreiter, C. G. JOM 1983, 241, 185.
17. Burt, J. C.; Knox, S. A. R.; McKinney, R. J.; Stone, F. G. A. JCS(D) 1977, 1.
18. Booth, B. L.; Hargreaves, R. G. JCS(A) 1970, 308.
19. DeShong, P.; Slough, G. A.; Sidler, D. R.; Rybczynski, P. J.; Von Philipsborn, W.; Kunz, R. W.; Bursten, B. E.; Clayton, T. W., Jr. OM 1989, 8, 1381.
20. DeShong, P.; Sidler, D. R.; Rybczynski, P. J.; Ogilvie, A. A.; Von Philipsborn, W. JOC 1989, 54, 5432.
21. Bennett, R. L.; Bruce, M. I.; Stone, F. G. A. JOM 1975, 94, 65.
22. Bennett, R. L.; Bruce, M. I.; Goodall, B. L.; Stone, F. G. A. AJC 1974, 27, 2131.
23. Motz, P. L.; Sheeran, D. J.; Orchin, M. JOM 1990, 383, 201.

M. G. Finn

University of Virginia, Charlottesville, VA, USA



Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.