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| Names | |
|---|---|
| IUPAC name Trimethylphosphine | |
| Other names trimethylphosphane | |
| Identifiers | |
| CAS Number | |
| ECHA InfoCard | 100.008.932 
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| CompTox Dashboard (EPA) | |
| Properties | |
| Chemical formula | C3H9P |
| Molar mass | 76.07 g/mol |
| Appearance | Colorless liquid, Pyrophoric |
| Density | 0.735 g/cm liquid |
| Melting point | -86 °C |
| Boiling point | 38-39 °C |
| Solubility in water | low |
| Solubility in other solvents | most organic solvents |
| Structure | |
| Coordination geometry | Trigonal pyramidal |
| Dipole moment | 1.19 Debye |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
| Main hazards | toxic |
| Related compounds | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa).
 Y verify (what is ?)
Infobox references
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Trimethylphosphine is the organophosphorus compound with the formula P(CH3)3, commonly abbreviated PMe3. This colorless liquid has a strongly unpleasant odour, which is characteristic of alkylphosphines. It is a pyramidal molecule with C3v symmetry, similar to ammonia (NH3) and phosphine (PH3). As a ligand, its cone angle is 118°. This angle, close to the optimal angles for sp-hybridisation, is an indication for the hybridisation of the phosphorus atom. The lone pair is left in an almost straight p-orbital, so it points rather localized outward, in contrast to the higher members of the nitrogen group, to open the route to the rather hard basic properties of the compound.
PMe3 is prepared using Grignard reagents:
The synthesis is conducted in a dibutyl ether, from which the more volatile PMe3 can be distilled.
Coordination chemistry
Trimethylphosphine is a highly basic ligand that forms complexes with most metals. The synthesis of an illustrative example is shown:
- PMe3 + Fe(CO)5 → Fe(CO)4PMe3 + CO
Its complex with silver iodide, AgI(PMe3) is a weighable, air stable solid that releases PMe3 upon heating.
Safety
PMe3 is potentially pyrophoric as well as toxic. PMe3 can be converted to non-pyrophoric phosphine oxide by treatment with dilute bleach.
References
- G. L. Miessler and D. A. Tarr “Inorganic Chemistry” 3rd Ed, Pearson/Prentice Hall publisher, ISBN 0-13-035471-6.
- Leutkens, Jr., M. L.; Sattelberger, A. P.; Murray, H. H.; Basil, J. D.; Fackler, Jr., J. P. (1990). Robert J. Angelici (ed.). "Trimethylphosphine". Inorganic Syntheses. 28. New York: J. Wiley & Sons: 305–310. doi:10.1002/9780470132593.ch76. ISBN 0-471-52619-3.
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