Sodium Pentacarbonylmanganate1,2


[13859-41-1]  · C5MnNaO5  · Sodium Pentacarbonylmanganate  · (MW 217.98) [LiMn(CO)5]

[15689-01-7]  · C5LiMnO5  · Lithium Pentacarbonylmanganate  · (MW 201.93) [(Ph3P)2N][Mn(CO)5]

[52542-59-3]  · C41H30MnNO5P2  · Bis(triphenylphosphoranylidene)ammonium Pentacarbonylmanganate  · (MW 733.60) [Mn(CO)5]-


(strong nucleophile for the preparation of alkyl-, acyl-, and silylmanganese compounds1,2)

Physical Data: gray or white powder when dried; usually prepared and used as cloudy gray-green solution in THF.

Solubility: Na, K, and Li salts: sol THF. PPN salt: very sol THF, CH2Cl2; sparingly sol benzene, diethyl ether; insol hexane.

Form Supplied in: not commercially available

Analysis of Reagent Purity: IR: M[Mn(CO)5]3,4 (M = Na, Li, K; THF, cm-1) 1897 ± 1 (s), 1862 ± 1 (s). PPN[Mn(CO)5]5 (nujol, cm-1) 1892 (s), 1856 (s), 1839 (m).

Preparative Methods: reduction of Decacarbonyldimanganese with Sodium Amalgam in THF (eq 1);6-8 the resulting solution is contaminated with approximately 10% (CO)5Mn-Hg-Mn(CO)5.7 Use of Sodium-Potassium Alloy (NaK2.8) provides mostly K[Mn(CO)5].4 Treatment of Mn2(CO)10 with 2.5 equiv Lithium Triethylborohydride in THF affords clean Li[Mn(CO)5] (eq 2).3 The potassium salt may be prepared similarly with Potassium Tri-s-butylborohydride (eq 3).3

Purification: usually used without purification; the PPN salt (PPN = [(Ph3P)2N]+) may be obtained as large yellow crystals by treatment with PPNCl and recrystallization from THF and petroleum ether.3-5

Handling, Storage, and Precautions: solutions of the pentacarbonylmanganate anion decompose rapidly upon exposure to air or moisture, and are usually used immediately after generation. The PPN salt may be handled in air in the solid state, but darkens after several days exposure. Use in a fume hood.

Reactions with Electrophiles.

[Mn(CO)5]- is highly nucleophilic, reacting at the metal center with a variety of electrophiles (eq 4). Most important are reactions with alkyl, acyl, and silyl halides,1-3,9-11 giving organomanganese complexes that undergo subsequent insertion or decarbonylation reactions (see also Pentacarbonylmethylmanganese, Pentacarbonylphenylmanganese, and Pentacarbonyl(trimethylsilyl)manganese). [Mn(CO)5]- also reacts cleanly with elemental iodine,6 Sn and Ge halides,5 TlNO3 (giving Tl[Mn(CO)5]3),12 and strongly electron-deficient vinyl halides.13,14

Generation of Ketenes.

Reaction of a-bromoacyl halides with [PPN][Mn(CO)5] in chloroform comprises a convenient method for the generation of pure solutions of ketenes (eq 5).15

1. Ellis, J. E. JOM 1975, 86, 1.
2. King, R. B. ACR 1970, 3, 417.
3. Gladysz, J. A.; Williams, G. M.; Tam, W.; Johnson, D. L.; Parker, D. W.; Selover, J. C. IC 1979, 18, 553.
4. Ellis, J. E.; Flom, E. A. JOM 1975, 99, 263.
5. Duffy, D. N.; Nicholson, B. K. JOM 1979, 164, 227.
6. (a) Reimer, K. J.; Shaver, A. Inorg. Synth. 1990, 28, 155. (b) King, R. B.; Stone, F. G. A. Inorg. Synth. 1963, 7, 198.
7. King, R. B. J. Inorg. Nucl. Chem. 1963, 25, 1296.
8. King, R. B. Organomet. Synth. 1965, 1, 148.
9. Bruce, M. I.; Liddell, M. J.; Pain, G. N. Inorg. Synth. 1989, 26, 171.
10. Dombek, B. D. JACS 1979, 101, 6466.
11. DeShong, P.; Slough, G. A.; Elango, V.; Trainor, G. L. JACS 1985, 107, 7788.
12. Hsieh, A. T. T.; Mays, M. J. Inorg. Synth. 1976, 16, 61.
13. Robinson, R.; Rudolf, K.; Koenig, T. JOC 1985, 50, 5871.
14. King, R. B.; Howard, J. W., Jr. JOC 1977, 42, 2335.
15. Masters, A. P.; Sorensen, T. S.; Ziegler, T. JOC 1986, 51, 3558.

M. G. Finn

University of Virginia, Charlottesville, VA, USA

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