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| Identifiers | |
|---|---|
3D model (JSmol) | |
| ChemSpider | |
PubChem CID | |
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| Properties | |
| C18H54P6W | |
| Molar mass | 640.31 |
| Appearance | yellow crystalline solid |
| Structure | |
| Cubic | |
| Im3m | |
| Related compounds | |
Other cations | Mo(PMe3)6 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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.
Compared to other zerovalent homoleptic trimethylphosphine complexes, W(PMe3)6 was less straightforward to synthesize and isolate. Previous attempts to prepare W(PMe3)6 by co-condensation (a modification of metal vapor synthesis) of tungsten with PMe3 and reduction of WCl6 with alkali metal reducing agents only formed the cyclometalated W(PMe3)4(η2-CH2PMe2)H [1] .
W(PMe3)6 was first isolated in 1990 by Parkin and Rabinovich. [2] It was prepared by the reduction of WCl6 with Na(K) alloy, using PMe3 as a reactive solvent.
Previous attempts to synthesize W(PMe3)6 placed the Na(K) alloy in a glass ampoule in a liquid nitrogen bath, condensed PMe3 into the ampoule, then added WCl6. Following this addition, the ampoule warmed to room temperature and stirred at room temperature for 2 weeks. Parkin and Rabinovich modified this preparation by simply stirring a mixture of WCl6 and Na(K) alloy in PMe3 at room temperature for 10 days.
The complex was crystallographically characterized, demonstrating W-P bond lengths of 2.455 ± 0.01 Å (245.5 ± 1.0 pm) and P-W-P bond angles of 90° and 180°.
W(PMe3)6 demonstrates ΔH° = 9.3 kcal/mol (39 kJ/mol) and ΔS° = 37 eu (150 J K-1 mol-1) for the dissociation of PMe3.
In the solid state, W(PMe3)6 is stable at room temperature for at least two weeks. However, it is unstable in 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.
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. [3] These complexes have been shown to be capable of activating C-H and other otherwise unreactive σ-bonds via oxidative addition, often forming cyclometalated products. [2]
W(PMe3)6 possesses an 18-electron valence count, and as such demonstrates somewhat limited reactivity. Much of the most interesting and varied chemistry occurs from its dissociated variants, such as W(PMe3)5.
W(PMe3)6 can catalyze the metathesis of phosphorus-phosphorus double-bonds. Interaction of the appropriate dichlorophosphane with W(PMe3)6 leads to dechlorination and formation of symmetrical and unsymmetrical diphosphenes.
The resultant phosphorus-tungsten species can also catalyze the exchange of diphosphene end-groups.
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.
Alkyne metathesis is an organic reaction that entails the redistribution of alkyne chemical bonds. The reaction requires metal catalysts. Mechanistic studies show that the conversion proceeds via the intermediacy of metal alkylidyne complexes. The reaction is related to olefin metathesis.
Diphosphene is a type of organophosphorus compound that has a phosphorus–phosphorus double bond, denoted by R-P=P-R'. These compounds are not common but are of theoretical interest. Normally, compounds with the empirical formula RP exist as rings. However, like other multiple bonds between heavy main-group elements, P=P double bonds can be stabilized by a large steric hindrance from the substitutions. The first isolated diphosphene bis(2,4,6-tri-tert-butylphenyl)diphosphene was exemplified by Masaaki Yoshifuji and his coworkers in 1981, in which diphosphene is stabilized by two bulky phenyl group.
Tungsten hexachloride is an inorganic chemical compound of tungsten and chlorine with the chemical formula WCl6. This dark violet blue compound exists as volatile crystals under standard conditions. It is an important starting reagent in the preparation of tungsten compounds. Other examples of charge-neutral hexachlorides are rhenium(VI) chloride and molybdenum(VI) chloride. The highly volatile tungsten hexafluoride is also known.
In organic chemistry, carbon–hydrogen bond functionalization is a type of organic reaction in which a carbon–hydrogen bond is cleaved and replaced with a C−X bond. The term usually implies that a transition metal is involved in the C−H cleavage process. Reactions classified by the term typically involve the hydrocarbon first to react with a metal catalyst to create an organometallic complex in which the hydrocarbon is coordinated to the inner-sphere of a metal, either via an intermediate "alkane or arene complex" or as a transition state leading to a "M−C" intermediate. The intermediate of this first step can then undergo subsequent reactions to produce the functionalized product. Important to this definition is the requirement that during the C−H cleavage event, the hydrocarbyl species remains associated in the inner-sphere and under the influence of "M".
Trimethylphosphine is an organophosphorus compound with the formula P(CH3)3, commonly abbreviated as PMe3. This colorless liquid has a strongly unpleasant odor, characteristic of alkylphosphines. The compound is a common ligand in coordination chemistry.
Hexamethyltungsten is the chemical compound W(CH3)6 also written WMe6. Classified as a transition metal alkyl complex, hexamethyltungsten is an air-sensitive, red, crystalline solid at room temperature; however, it is extremely volatile and sublimes at −30 °C. Owing to its six methyl groups it is extremely soluble in petroleum, aromatic hydrocarbons, ethers, carbon disulfide, and carbon tetrachloride.
Germylenes are a class of germanium(II) compounds with the general formula :GeR2. They are heavier carbene analogs. However, unlike carbenes, whose ground state can be either singlet or triplet depending on the substituents, germylenes have exclusively a singlet ground state. Unprotected carbene analogs, including germylenes, has a dimerization nature. Free germylenes can be isolated under the stabilization of steric hindrance or electron donation. The synthesis of first stable free dialkyl germylene was reported by Jutzi, et al in 1991.
Alexander C. Filippou has been a Professor of Inorganic Chemistry at the Rheinische-Friedrich-Wilhelms-University Bonn since 2005.
Organomolybdenum chemistry is the chemistry of chemical compounds with Mo-C bonds. The heavier group 6 elements molybdenum and tungsten form organometallic compounds similar to those in organochromium chemistry but higher oxidation states tend to be more common.
A transition metal fullerene complex is a coordination complex wherein fullerene serves as a ligand. Fullerenes are typically spheroidal carbon compounds, the most prevalent being buckminsterfullerene, C60.
Transition metal benzyne complexes are organometallic complexes that contain benzyne ligands (C6H4). Unlike benzyne itself, these complexes are less reactive although they undergo a number of insertion reactions.
Germanium(II) hydrides, also called germylene hydrides, are a class of Group 14 compounds consisting of low-valent germanium and a terminal hydride. They are also typically stabilized by an electron donor-acceptor interaction between the germanium atom and a large, bulky ligand.
Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile.
A transition metal phosphido complex is a coordination complex containing a phosphido ligand (R2P, where R = H, organic substituent). With two lone pairs on phosphorus, the phosphido anion (R2P−) is comparable to an amido anion (R2N−), except that the M-P distances are longer and the phosphorus atom is more sterically accessible. For these reasons, phosphido is often a bridging ligand. The -PH2 ion or ligand is also called phosphanide or phosphido ligand.
Transition metal silane complexes are coordination compounds containing hydrosilane ligands. An early example is (MeC5H4)Mn(CO)2(η2-HSiPh3) (Ph = C6H5).
Arsenic in the solid state can be found as gray, black, or yellow allotropes. These various forms feature diverse structural motifs, with yellow arsenic enabling the widest range of reactivity. In particular, reaction of yellow arsenic with main group and transition metal elements results in compounds with wide-ranging structural motifs, with butterfly, sandwich and realgar-type moieties featuring most prominently.
1-Phosphaallenes is are allenes in which the first carbon atom is replaced by phosphorus, resulting in the structure: -P=C=C<.
m-Terphenyls (also known as meta-terphenyls, meta-diphenylbenzenes, or meta-triphenyls) are organic molecules composed of two phenyl groups bonded to a benzene ring in the one and three positions. The simplest formula is C18H14, but many different substituents can be added to create a diverse class of molecules. Due to the extensive pi-conjugated system, the molecule it has a range of optical properties and because of its size, it is used to control the sterics in reactions with metals and main group elements. This is because of the disubstituted phenyl rings, which create a pocket for molecules and elements to bond without being connected to anything else. It is a popular choice in ligand, and the most chosen amongst the terphenyls because of its benefits in regards to sterics. Although many commercial methods exist to create m-terphenyl compounds, they can also be found naturally in plants such as mulberry trees.
Stable and persistent phosphorus radicals are phosphorus-centred radicals that are isolable and can exist for at least short periods of time. Radicals consisting of main group elements are often very reactive and undergo uncontrollable reactions, notably dimerization and polymerization. The common strategies for stabilising these phosphorus radicals usually include the delocalisation of the unpaired electron over a pi system or nearby electronegative atoms, and kinetic stabilisation with bulky ligands. Stable and persistent phosphorus radicals can be classified into three categories: neutral, cationic, and anionic radicals. Each of these classes involve various sub-classes, with neutral phosphorus radicals being the most extensively studied. Phosphorus exists as one isotope 31P (I = 1/2) with large hyperfine couplings relative to other spin active nuclei, making phosphorus radicals particularly attractive for spin-labelling experiments.
Pentakis(trimethylphosphine)tungsten (W(PMe3)5, Me=CH3) and its physically relevant "tucked-in" isomer, [(dimethylphosphino-κP)methyl-κC]hydrotetrakis(trimethylphosphine)tungsten (W(PMe3)4(η2-CH2PMe2)H), are organotungsten complexes. Formally, the former is a tungsten(0) complex, whereas the latter is a tungsten(II) complex. W(PMe3)4(η2-CH2PMe2)H's tungsten center is electron-rich and, thus, prone to oxidation. W(PMe3)4(η2-CH2PMe2)H has been used as a starting retron for some challenging chemistry, such as C-C bond activation, tungsten-chalcogenide multiple bonding, tungsten-tetrel multiple bonding, and desulfurization.