tert-Butyl isocyanide
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| tert-Butyl isocyanide | |
|---|---|
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| Other names | t-BuNC, propane, 2-isocyano-2-methyl |
| Identifiers | |
| CAS number | [7188-38-7] |
| Properties | |
| Molecular formula | C5H9N |
| Molar mass | 83.13 g/mol |
| Appearance | Colorless liquid |
| Density | 0.735 g/cm³, liquid |
| Melting point |
? °C |
| Boiling point |
91 °C |
| Solubility in water | N/A |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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tert-Butyl isocyanide is an organic compound with the formula Me3CNC (Me = methyl, CH3). It is an isocyanide, commonly called isonitrile or carbylamine, as defined by the functional group C≡N-R. tert-Butyl isocyanide, like most alkyl isocyanides, is a reactive colorless liquid with an extremely unpleasant odor. It forms stable complexes with transition metals and can insert into metal-carbon bonds.[1]
tert-Butyl isocyanide is prepared by a Hofmann carbylamine reaction. In this conversion, a dichloromethane solution of tert-butylamine is treated with chloroform and aqueous sodium hydroxide in the presence of catalytic amount of the phase transfer catalyst benzyltriethylammonium chloride.[2]
- Me3CNH2 + CHCl3 + 3 NaOH → Me3CNC + 3 NaCl + 3 H2O
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[edit] Coordination chemistry
By virtue of the lone electron pair on carbon, isocyanides serves as ligands in coordination chemistry, especially with metals in the 0, +1, and +2 oxidation states. tert-Butyl isocyanide has been shown to stabilize metals in unusual oxidation states, such as Pd(I).[3]
- Pd(dba)2 + PdCl2(C6H5CN)2 + 4 t-BuNC → PdCl2(t-BuNC)4 + 2 dba + 2 C6H5CN
tert-Butyl isocyanide can form hepta-coordinate homoleptic complexes, despite having a large t-Bu group, which is held far away from the metal center because of the linearity of the M-C≡N-C linkages.[4]
[edit] Similarity to metal carbonyls
tert-Butyl isocycanide forms complexes that are stoichiometrically analogous to certain binary metal carbonyl complexes, such as Fe2(CO)9 and Fe2(tBuNC)9.[5] Although structurally similar, the analogous carbonyls differ in several ways, mainly because t-BuNC is a better donor ligand than CO. Thus, Fe(tBuNC)5 is easily protonated, whereas its counterpart Fe(CO)5 is not.[6]
[edit] Insertion into metal-carbon bonds
Under certain circumstances, tert-butyl isocyanide has been shown to insert into metal-carbon bonds to form iminoacyls. The insertion of isocyanides into metal-carbon bonds is of potential relevance in organic synthesis.[7]
[edit] Safety
In keeping with its similarity to carbon monoxide, tert-butyl isocyanide is toxic.
[edit] References
- ^ Malatesta, L. Isocyanide Complexes of MetalsProgress in Inorganic Chemistry, 1959, volume 1, 284-291.
- ^ Gokel, G.W.; Widera, R.P.; Weber, W.P. (1988). "Phase-transfer Hofmann carbylamine reaction: tert-butyl isocyanide". Org. Synth.; Coll. Vol. 6: 232.
- ^ Rettig, M.F.; Maitlis, P.M. Tetrakis (tert-butyl isocyanide)D-μ-chloro-dipalladium. Inorganic Syntheses, 1990, 28, 110-113. ISBN 0-470-13259-0.
- ^ Carnahan, E.M.; Protasiewicz, J.D.; Lippard, S.J. 15 years of reductive coupling: what have we learned? Acc. Chem. Res. 1993, 26, 90-97
- ^ Bassett, J.M.; Barker, G.K.; Green, M.; Howard, J.A.; Stone, G.A.; Wolsey, W.C. "Chemistry of low-valent metal isocyanide complexes" J.C.S. Dalton, 1981, 219-227.
- ^ Bassett, J.M.; Farrugia, L.J.; Stone, G.A. "Protonation of pentakis(t-butyl isocyanide)iron" J.C.S. Dalton, 1980, 1789-1790.
- ^ 7. Vicente, J; Abad, J.A.; Fortsch, W.; Lopez-Saez, M.J. Reactivity of ortho-palladated phenol derivatives with unsaturated molecules. Organometallics, 2004, 23, 4414-4429. DOI 10.1021/om0496131.
