Pentacarbonylhydridomanganese
5-2D.png)
| |
| Names | |
|---|---|
| Other names
Hydrogen pentacarbonylmanganate(-I) (7CI); Manganese, pentacarbonylhydro- (8CI); Hydridomanganese pentacarbonyl; Hydridopentacarbonylmanganese; Manganese pentacarbonyl hydride; Pentacarbonylhydromanganese; Pentacarbonylmanganese hydride
| |
| Identifiers | |
| Properties | |
| HMn(CO)5 | |
| Molar mass | 195.99799 g/mol |
| Appearance | At room temperature, it is liquid and colorless. Below its melting point, it may be sublimed in vacuum.[1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Pentacarbonylhydridomanganese is an organometallic compound with formula HMn(CO)5. This compound is one of the most stable "first-row" transition metal hydrides.
Preparation
It was first reported in 1931.[2] Of the several ways to produce this compound,[3] is the protonation of the pentacarbonyl manganate anion. The latter is formed from reduction of dimanganese decacarbonyl (Mn(CO)5)2. The reaction is shown below.
- LiHB(C2H5)3 (Superhydride) + ½Mn2(CO)10 → Li[Mn(CO)5] + ½H2 + (C2H5)3B
- Li[Mn(CO)5] + CF3SO3H → HMn(CO)5 + Li+
CF3SO3−
Salts of [Mn(CO)5]−
can be isolated as crystalline PPN+
(μ-nitrido—bis-(triphenylphosphorus)) salt, which is smoothly protonated by CF3SO3H.[3]
- PPN[Mn(CO)5] + CF3SO3H → HMn(CO)5 + PPN+
CF3SO3−
This compound can also be formed by the reaction of a solution of pentacarbonyl(trimethylsilyl)manganese with water.[4] The reaction is shown below.
- 2(CO)5MnSiMe3 + H2O → HMn(CO)5 + Me3SiOSiMe3
Structure and Properties
The compound has octahedral symmetry [5] and its molecular point group is C4v.[6] The H-Mn bond length is 1.44 ± 0.03 Å.[6] A gas phase electron diffraction study confirms this data.
The structure of HMn(CO)5 has been studied by many methods including X-Ray diffraction, neutron diffraction, and electron diffraction.[6] HMn(CO)5 can be related to the structure of a hexacarbonyl complex such as Mn(CO)+
6, and therefore has the following similar properties.[7] The occupied molecular orbitals on the top are the 2 t2g orbitals. They are characterized as metal 3dπ orbitals. Since the antibonding 2π orbitals interact with the carbonyl groups, (or in this case, H−
) the t2g orbital is stabilized compared to the 3dπ orbital, which in turn will cause changes in the sigma and pi interactions.
Main Reactions
The pKa of HMn(CO)5 is 15.1.[8] It is thus comparable to hydrogen sulfide, a common inorganic acid, in its acidity.
A common reaction involving the HMn(CO)5 species is substitution of the CO ligands by organophosphines, as occurs both thermally and photochemically.[9] In this way the following derivatives form MnH(CO)3P2, MnH(CO)2P3, and MnH(CO)P4, (where P = P(OEt)3, PPh(OEt)2, PPh2OEt, PPh(OiPr)2.
The compound HMn(CO)5 can be used to reduce olefins and other organic compounds, as well as metal halides.[3]
Carbonyl ligands are substituted in this complex with the appropriate phosphite, resulting in the complexes shown above.
This compound can be methylated with diazomethane.[1]
- HMn(CO)5 + CH2N2 → Mn(CO)5CH3 + N2
Notes
- ^ a b Eley, D.D.; Pines, Herman; Weisz, P.B. Advances In Catalysis. 32. 385. ISBN 978-0-12-007832-5
- ^ Hieber, W. Leutert, F. Naturwissenschaften. 1931. 360.
- ^ a b c Hunter, Alan D; Bianconi, Larry J; DiMuzio, Steven J; Braho, Dianne L. Synthesis and Structure- Property Relationships in η6-Arene) Cr(CO)3 Chemistry: From Guided Experiments to Discovery Research. J. Chem. Educ. 75. 1998. 891. doi:10.1021/ed075p891
- ^ Finn, M.G. Pentacarbonyl(trimethylsilyl)manganese. Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rp022s
- ^ Liu, Xian-mei; Wang, Chao-yang; Qian-shu; Xie; Yaoming; King, R. Bruce; Schaefer, Henry F., III. Mononuclear and binuclear manganese carbonyl hydrides. Dalton Trans., 2009, 3774-3785, doi:10.1039/b822913a
- ^ a b c Kukolich, S.G. Microwave Spectrum and Molecular Structure for Manganese Pentacarbonyl Hydride. 33. 1994. 1217-1219
- ^ Fenske, Richard. Electronic Structure and Bonding in Manganese Pentacarbonyl Halides and Hydride. Inorganic Chemistry. 9. 1970. 1053-1060.
- ^ Moore, E. J.; Sullivan, J. M. and Norton, J. R., Thermodynamic Acidity of Common Mononuclear Carbonyl Hydrides, J. Am. Chem. Soc., 1986. 108, 2261.
- ^ Albertin, Gabriele. Cationic Molecular Hydrogen Complexes of Mn (I). Organometallics. 16. 1997. 4959-4969.