Hexakis(trimethylphosphine)tungsten
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| Identifiers | |
|---|---|
| Properties | |
| C18H54P6W | |
| Molar mass | 640.31 |
| Appearance | yellow crystalline solid |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hexakis(trimethylphosphine)tungsten is a tungsten(0) organometallic compound with the formula W(P(CH3)3)6. It is a yellow crystalline solid soluble in organic solvents.
Synthesis and characterization
W(PMe3)6 was first isolated in 1990 by Parkin and Rabinovich.[1] It was prepared by the reduction of WCl6 with Na(K) alloy, using PMe3 as a reactive solvent.
tungsten.png)
The complex was crystallographically characterized, demonstrating W-P bond lengths of 2.455(5) Å and P-W-P bond angles of 90° and 180°.
W(PMe3)6 demonstrates ΔH° = 9.3 kcal/mol and ΔS° = 37 eu.
Stability
In the solid state, W(PMe3)6 is stable at room temperature for at least two weeks. However, it is unstable and solution and rapidly converts to an equilibrium mixture between W(PMe3)4(η2-CH2PMe2)H and PMe3 with Keq = 17.8 M at 30 °C.
tungsten_in_solution.png)
Reactivity
W(PMe3)6 and other metal complexes of the form M(PMe3)n contain very electron-rich and highly-reactive metal centers as a result of the combination of the strong σ-donating and π-accepting nature of the PMe3 ligand.[2] The electron-rich metal centers of W(PMe3)6 and similar metal complexes have been shown to be capable of activating C-H and other otherwise unreactive σ-bonds via oxidative addition, often forming cyclometalated products.[1]
W(PMe3)6 can catalyze the metathesis of phosphorous-phosphorous double-bonds. Interaction of the appropriate dichlorophosphane with W(PMe3)6 leads to dechlorination and formation of symmetrical and unsymmetrical diphosphenes.
The resultant phosphorous-tungsten species can also catalyze the exchange of diphosphene end-groups.
Formation of metal-germanium triple bonds[2]
The W(PMe3)4(η2-CH2PMe2)H species formed upon the dissolution of W(PMe3)6 can participate in a Ge-Cl bond heterolysis and form a metal-germanium triple bond.
References
- ^ a b Rabinovich, Daniel; Parkin, Gerard (1990). "Hexakis(trimethylphosphine)tungsten(0): synthesis, structure, and reactivity". Journal of the American Chemical Society. 112 (13): 5381–5383. doi:10.1021/ja00169a073. ISSN 0002-7863.
- ^ a b Filippou, Alexander C.; Weidemann, Nils; Philippopoulos, Athanassios I.; Schnakenburg, Gregor (2006-09-11). "Activation of Aryl Germanium(II) Chlorides by [Mo(PMe 3 ) 6 ] and [W(η 2 ‐CH 2 PMe 2 )H(PMe 3 ) 4 ]: A New Route to Metal–Germanium Triple Bonds". Angewandte Chemie International Edition. 45 (36): 5987–5991. doi:10.1002/anie.200602061. ISSN 1433-7851.
- ^ Dillon, Keith B.; Fox, Mark A.; Gibson, Vernon C.; Goodwin, Helen P.; Sequeira, Leila J. (2017-02-15). "Platinum(II) complexes of some unsymmetrical diphosphenes". Journal of Organometallic Chemistry. 830: 113–119. doi:10.1016/j.jorganchem.2016.10.005. ISSN 0022-328X.
- ^ Dillon, Keith B.; Gibson, Vernon C.; Sequeira, Leela J. (1995-01-01). "Transition-metal catalysed metathesis of phosphorus–phosphorus double bonds". Journal of the Chemical Society, Chemical Communications (23): 2429–2430. doi:10.1039/C39950002429. ISSN 0022-4936.