chemistry

Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride

Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride rather than just read about it. In short: Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride is the organotungsten compound with the formula W(PMe3)4(η2-CH2PMe2)H. In this complex, the formal oxidation state of W is 2+, and the tungsten center has bonded four trimethylphosphine ligands.

Key takeaways

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Reference excerpt

Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride is the organotungsten compound with the formula W(PMe3)4(η2-CH2PMe2)H. In this complex, the formal oxidation state of W is 2+, and the tungsten center has bonded four trimethylphosphine ligands. The remaining three ligands are a CH2PMe2, bonded in η2 fashion, and hydride. The complex reacts with many simple reagents.

Synthesis W(PMe3)4(η2-CH2PMe2)H can be synthesized by treating tungsten hexachloride with trimethylphosphine and sodium. Other techniques produce a family of related complexes. Thus excess PMe3 and H2 produces W(PMe3)4(η2-CH2PMe2)H in a 3:1 mixture with W(PMe3)5H2, co-condensation produces only W(PMe3)4(η2-CH2PMe2)H, and reduction with Na-K alloy requires vast PMe3 excess and only produces a mixture of W(PMe3)4(η2-CH2PMe2)H and W(PMe3)6. W(PMe3)4(η2-CH2PMe2)H is thermodynamically favored relative to W(PMe3)6, as described in the equation:

W(PMe3)6 ↽ − ⇀ {\displaystyle {\ce {<=>>}}} W(PMe3)4(η2−CH2PMe2)H + PMe3 ΔGrxn = –1.73 kcal mol−1 W(PMe3)5, a 16 electron, d6 complex, has been proposed as an unstable intermediate between W(PMe3)4(η2-CH2PMe2)H and W(PMe3)6. The rate-determining step from W(PMe3)6 is dissociation of PMe3. Isotopic labeling and the NMR studies indicate that W(PMe3)4(η2-CH2PMe2)H is fluxional such that all methyl groups are equivalenced.

Reactivity

Small molecule substrates: H2, CO, N2, CO2, SiH4 W(PMe3)4(η2-CH2PMe2)H reacts with H2 to give W(PMe3)5(H)2...

...and W(PMe3)4(H)4. With HD, W(PMe3)4(η2-CH2PMe2)H converts to W(PMe3)5HD or W(PMe3)4(η2-HD) in PMe3 solvent. W(PMe3)4(η2-CH2PMe2)H adds N2 to give W(PMe3)5(N2):

In 2 atmospheres of CO, W(PMe3)4(η2-CH2PMe2)H gives fac-W(PMe3)3(CO)3:

3 atmosphere of a 1:1 CO2/H2 gas mix to produce W(PMe3)4(κ2-O2CO)H2 and a bimetallacycle:

The reaction of W(PMe3)4(η2-CH2PMe2)H with SiH4 yields W(PMe3)4(SiH3)2H2. Organosilanes give a variety of products:

Acids HBF4 reacts with W(PMe3)4(η2-CH2PMe2)H in ether to give [W(PMe3)4(OH)2H2][BF4]2. Several derivatives are known: W(PMe3)4H4, W(PMe3)4F2H2, and [W(PMe3)4F(H2O)H2]F. Hydrogen chloride reacts as follows:

W(PMe3)4(η2-CH2PMe2)H + 2 HCl → W(PMe3)4Cl2(H)2 + PMe3 The corresponding dibromide and diiodide form by salt metathesis. Carboxylic acid reacts with W(PMe3)4(η2-CH2PMe2)H to give hydride complexes, e.g., W(PMe3)4(O2CR)H.

π-systems In 1-2 atmospheres of ethylene at room temperature, W(PMe3)4(η2-CH2PMe2)H reacts to form trans-W(PMe3)4(η2-C2H4)2. Upon subjecting W(PMe3)4(η2-CH2PMe2)H to 2 atmospheres of ethylene at 60 °C in the presence of light petroleum for a week, W(PMe3)2(η2-C4H6)2 is produced. W(PMe3)4(η2-CH2PMe2)H will ligate to buta-1,3-diene when the latter is in vast excess and in the presence of light petroleum at 50 °C to make the same product as ethylene. W(PMe3)2(η2-C4H6)2 produces yellow crystals. Much like with ethylene, propylene (2 atm) also forms C-C bonds upon reaction with W(PMe3)4(η2-CH2PMe2)H and light petroleum at 70 °C. The resultant product is W(PMe3)3[η-CH2=C(Me)CH=C(cis-Me)H]H2. W(PMe3)4(η2-CH2PMe2)H, upon reaction with cyclopentadiene in light petroleum for five days, binds cyclopentadiene and dissociates two PMe3 ligands to generate W(η5-C5H5)(PMe3)3H, W(PMe3)4H4, W(PMe3)3H6, and trace W(η5-C5H5)2H2. The crystals of this mixture are yellow and air-sensitive.

In the reaction with quinoxaline (QoxH,HH) and its derivatives 6-methylquinoxaline (QoxMe,HH) and 6,7-dimethylquinoxaline (QoxMe,MeH), W(PMe3)4(η2-CH2PMe2)H forms [κ2-C2-C6RR'H2(NC)2]W(PMe3)4, (η4-C2N2-QoxR,R'H)W(PMe3)3H2 (vide infra), and W(PMe3)4H2 (R,R'=H, Me), wherein the first listed product is generated from C-C bond cleavage to form two W=C=B bond motifs. The latter two products are hypothesized to be formed from H2 generated from the C-C bond cleavage.

Methanol W(PMe3)4(η2-CH2PMe2)H, upon addition of methanol in an ethylene atmosphere, can form W(PMe3)4(CO)H2.

W(PMe3)4(η2-CH2PMe2)H, upon MeOH ligation in an η2-fashion, dissociates PMe3 and forms W(PMe3)4(η2-CH2O)H2. This complex undergoes many similar reaction pathways as its precursor retron.

Tungsten-tetrel multiple bonding W(PMe3)4(η2-CH2PMe2)H, in pentane and at −20 °C, reacts with Ge(C6H3-2,6-Trip2)Cl (Trip=C6H2-2,4,6-iPr3, iPr=CH(CH3)2) to dissociate PMe3 and generate trans-[Cl(H)(PMe3)3W{=Ge(C6H3-2,6-Trip2)(CH2PMe2)}]. This green, air-sensitive complex can heated at 50 °C with toluene or left in ambient conditions with either toluene or pentane to yield the Ge≡C bond-containing complex, trans-[Cl(PMe3)4W≡Ge-C6H3-2,6-Trip2]. This brown, air-sensitive complex can also be directly generated from W(PMe3)4(η2-CH2PMe2)H by heating with toluene and Ge(C6H3-2,6-Trip2)Cl at 50 °C. trans-[Cl(PMe3)4W≡Ge-C6H3-2,6-Trip2] is, in turn, also a retron for further chemistry by substitution of the labile chloride ligand. Upon addition of lithium iodide in ether, chloride is substituted for iodide, forming red-brown trans-[I(PMe3)4W≡Ge-C6H3-2,6-Trip2]. With lithium dimethylamine in THF, the chloride is substituted for a hydride, generating red-brown, air-sensitive trans-[H(PMe3)4W≡Ge-C6H3-2,6-Trip2]. With potassium thiocynate in THF, chloride is substituted for thiocynate, forming dark brown trans-[(NCS)(PMe3)4W≡Ge-C6H3-2,6-Trip2].

W(PMe3)4(η2-CH2PMe2)H with 0.5 equivalent of {Pb(Trip)Br2}2 and in toluene at 50 °C produces (PMe3)4BrW{≡Pb(C6H3-2,6-Trip2)}. Upon addition of lithium dimethylamine in THF, Br(PMe3)4W{≡Pb(C6H3-2,6-Trip2)} converts to brown, air-sensitive H(PMe3)4W{≡Pb(C6H3-2,6-Trip2)}. Alternatively, W(PMe3)4(η2-CH2PMe2)H, with 0.5 equivalent of {Pb(Trip)NMe2}2 (produced from the reaction of {Pb(Trip)Br2}2 with lithium dimethylamine) in toluene and at 80 °C, also produces H(PMe3)4W{≡Pb(C6H3-2,6-Trip2)}.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride

Start with the simplest possible case. Write down what Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride

In research: Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hydrido complexes, Organotungsten compounds, Phosphine complexes, so understanding it makes those chapters shorter.
In everyday life: Look for Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Frequently asked questions

What is Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride in simple terms?

Why does Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Tetrakis(trimethylphosphine)tungsten(II) trimethylphospinate hydride.