[14100-30-2]  · C5ClMnO5  · Pentacarbonylchloromanganese  · (MW 230.44)

(precursor to reactive carbonyl halide complexes;2 precatalyst for the oligomerization of benzyl chloride3)

Physical Data: pale yellow crystals; sublimes at 40 °C/0.1 mmHg.

Solubility: sol CH2Cl2; moderately sol benzene, toluene; v sl sol hexane.

Form Supplied in: not commercially available. (CO)5MnBr is available from commercial sources as orange-yellow crystals.

Analysis of Reagent Purity: IR (CCl4, cm-1) 2140 (w), 2054 (s), 2021 (vw), 1998 (m).4 Related compounds: (CO)5MnBr 2134 (w), 2051 (s), 2020 (vw), 2000 (m); (CO)5MnI 2127 (w), 2045 (s), 2016 (vw, sh), 2005 (m)

Preparative Methods: (a) treatment of a CH2Cl2 solution of Decacarbonyldimanganese with 30 equiv Sulfuryl Chloride at rt, followed by evaporation, washing with ethanol, and drying in vacuo, affords pure (CO)5MnCl in 91% yield (eq 1).5 (b) a solution of Chlorine in CCl4 is added slowly to Mn2(CO)10 in CCl4 at 0 °C under a dry nitrogen atmosphere. After stirring at room temperature for 4 h, the precipitate is filtered in air, washed with CCl4, and dried in vacuo. The product is approximately 90% pure, the remainder being [MnCl(CO)4]2.1,6,7 (c) A solution of Mn2(CO)10 in CCl4 irradiated with UV-visible light gives (CO)5MnCl with high quantum yield; (CO)5MnI is also available by photolysis in the presence of I2.8

The related compounds (CO)5MnBr and (CO)5MnI may be prepared by methods similar to (b).1 In addition, the iodide may be obtained from Na[Mn(CO)5] and I2.1

Purification: (CO)5MnCl (40 °C/0.1 mmHg), (CO)5MnBr (50 °C/0.05 mmHg), and (CO)5MnI (50 °C/0.05 mmHg) are purified by sublimation and/or recrystallization from hydrocarbon solvents such as pentane or hexane.

Handling, Storage, and Precautions: light sensitive; dimerizes slowly in solution with loss of CO. The product, [MnCl(CO)4]2, is readily detected by IR (2104 (m), 2045 (vs), 2012 (s), 1975 (vs)).9 Pentacarbonylmanganese halides are indefinitely stable when stored as solids in the absence of air at -20 °C. While no information concerning the toxicity of these compounds is available, one should assume that metal carbonyls are highly toxic; since they are volatile solids, extra care should be taken to avoid exposure. Use in a fume hood.

Carbonyl Substitution.

Substitution of a CO ligand with a two-electron donor usually occurs cis to the halide (eq 2). The products are configurationally stable. Attacking ligands include monodentate or chelating phosphines and arsines,2 and silylphosphines, with subsequent hydrolysis of the P-Si bond to afford parent phosphine (P-H) complexes and dinuclear compounds under some conditions.10

Halide Substitution.11

Treatment with Silver(I) Trifluoromethanesulfonate affords the labile Mn(CO)5(OTf) complex, which may be treated by a variety of neutral two-electron donors to give cationic complexes [(CO)5Mn-L](OTf) (L = THF, MeCN, PBu3).11 The following compounds are available by displacement of both halide and CO ligands: (h3-allyl)Mn(CO)4, from attack of hydroxide ion on coordinated CO followed by loss of CO2 and alkylation with allyl bromide;12 (h5-C5Z4X)Mn(CO)3 (Z = H or Cl), from reaction with diazocyclopentadienides with transfer of the halide of the Cp fragment;7,13 and aminooxy- or dioxycarbene compounds from reaction with oxirane or aziridine and catalytic bromide ion.14

Oligomerization of Benzyl Chloride.

When heated at 100 °C with catalytic quantities of (CO)5MnCl or (CO)5MnBr, benzyl chloride is converted to highly branched oligomers linked at benzylic and aromatic ring sites.3 An average of 30-50 monomer units are incorporated per oligomer. The analogous rhenium complexes are also active, as are Group 6 carbonyl halides.

1. (a) Reimer, K. J.; Shaver, A. Inorg. Synth. 1990, 28, 155. (b) Reimer, K. J.; Shaver, A. Inorg. Synth. 1979, 19, 159.
2. Bond, A. M.; Colton, R.; Panagiotidou, P. OM 1988, 7, 1767.
3. Tsonis, C. P. J. Mol. Catal. 1985, 33, 61, and references therein.
4. Kaesz, H. D.; Bau, R.; Hendrickson, D.; Smith, J. M. JACS 1967, 89, 2844.
5. Davis, R.; Durrant, J. L. A.; Rowland, C. C. JOM 1986, 315, 119.
6. Abel, E. W.; Wilkinson, G. JCS 1959, 1501.
7. Brinkman, K. C.; Gladysz, J. A. OM 1984, 3, 147.
8. (a) Wrighton, M. S.; Ginley, D. S. JACS 1975, 97, 2065. (b) Hallock, S. A.; Wojcicki, A. JOM 1973, 54, C27.
9. Zingales, F.; Sartorelli, U. IC 1967, 6, 1243.
10. Effinger, G.; Hiller, W.; Lorenz, I. P. ZN(B) 1987, 42, 1315.
11. Nitschke, J.; Schmidt, S. P.; Trogler, W. C. IC 1985, 24, 1972.
12. Gibson, D. H.; Hsu, W.-L.; Ahmed, F. U. JOM 1981, 215, 379.
13. Berry, A. D.; MacDiarmid, A. G. Inorg. Nucl. Chem. Lett. 1969, 5, 601.
14. Singh, M. M.; Angelici, R. J. IC 1984, 23, 2699.

M. G. Finn

University of Virginia, Charlottesville, VA, USA

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