chemistry

Hexa(tert-butoxy)ditungsten(III)

Hexa(tert-butoxy)ditungsten(III) 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 Hexa(tert-butoxy)ditungsten(III) rather than just read about it. In short: Hexa(tert-butoxy)ditungsten(III) is a coordination complex of tungsten(III). It is one of the homoleptic alkoxides of tungsten.

Key takeaways

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Reference excerpt

Hexa(tert-butoxy)ditungsten(III) is a coordination complex of tungsten(III). It is one of the homoleptic alkoxides of tungsten. A red, air-sensitive solid, the complex has attracted academic attention as the precursor to many organotungsten derivatives. It an example of a charge-neutral complex featuring a W≡W bond, arising from the coupling of a pair of d3 metal centers.

Preparation W2(O-t-Bu)6 was first prepared by treating tungsten(III) dialkylamides with tert-butanol. W2(O-t-Bu)6 can also be synthesized from NaW2Cl7(THF)5 and NaO-t-Bu.

NaW2Cl7(THF)5 + 6 NaO-t-Bu → W2(O-t-Bu)6 + 7 NaCl + 5 THF

Structure As verified by X-ray crystallography, the two tungsten(III) centers are joined by a triple bond. Each W(III) is pseudotetrahedral. The W2O6 core adopts a staggered, ethane-like conformation, similar to that for its dimolybdenum analogue. The molecule has inversion symmetry.

Reactions

Hydrolysis This compound hydrolyzes at 200 °C to give WO2:

W2(O−t−Bu)6 + 2 H2O → 2 WO2 + 4 HO−t−Bu + 2 CH2=C(CH3)2

With carbon dioxide Carbon dioxide reacts reversibly with W2(O−t−Bu)6 to form green 2:1 adduct featuring two alkyl carbonate ligands.

W2(O−t−Bu)6 + 2 CO2 ⇌ W2(O−t−Bu)4(O2CO−t−Bu)2

With carbon monoxide Carbon monoxide react with W2(O−t−Bu)6 to give W2(O−t−Bu)6CO. In this adduct, the carbonyl ligand bridges between two W(III) atoms.. This compound can further react with i-PrOH to generate W4(μ-CO)2(O-i-Pr)12. The higher nuclearity of this isopropoxide can be attributed to the smaller size of the isopropoxyl ligands.

With alkynes W2(O−t−Bu)6 reacts with alkynes to give RC≡W(O-t-Bu)3, tetrahedral alkylidyne complexes. In these complexes, tungsten is electrophilic and the alkylidyne carbon is nucleophilic.

W2(O−t−Bu)6 + RC≡CR → 2 RC≡W(O−t−Bu)3 (R can be Me, Et, Pr) The reaction proceed in minutes near room temperature. The rate increases in the following order: 4-octyne, 3-hexyne, 2-butyne. The resulting alkylidyne compounds are colorless solids that sublime near room temperature. W2(O−t−Bu)6 does not react with diphenylacetylene or bis(trimethylsilyl)acetylene. These results are attributed to unfavorable electronic and steric effects, respectively. On the other hand, W2(O−t−Bu)6 reacts with two equivalents of EtC≡CPh, EtC≡CSiMe3, and EtC≡C–CH=CH2 to form corresponding alkylidyne complexes. Thus, W2(O−t−Bu)6 reacts more easily with asymmetric substitute acetylenes than symmetric ones. The reactions with alkynes initially afford adducts with a bridging ("μ-perpendicular") alkyne with elongated WW bonds and CC (alkyne) bonds. This intermediate is analogue to other dimetallatetrahedranes. These adducts convert into RC≡W(O-t-Bu)3. The resulting alkylidyne complexes RC≡W(O-t-Bu)3 catalyze alkyne metathesis reactions. Besides simple metathesis reactions, W2(O-t-Bu)6 also reacts with 3-hexyne in a 1:1 molar ratio to form a triangular tritungsten complex compound [W3(O-t-Bu)5(μ-O)(μ-CEt)O]2. This reaction has a two steps mechanism; first is the C≡C and W≡W metathesis reaction and follow by formal addition of carbyne (W≡C) to alkoxide (W2): W2(O-t-Bu)6 + RC≡CR → 2[RC≡W(O-t-Bu)3] W2(O−t−Bu)6 + RC≡W(O−t−Bu)3 → W3(O−t−Bu)5(μ−O)(μ−CEt)O

W3(O−t−Bu)5(μ−O)(μ−CEt)O → [W3(O−t−Bu)5(μ−O)(μ−CEt)O]2 W2(O−t−Bu)6 also reacts with EtC≡CC≡CEt to form (t-Bu-O)3W≡CC≡W(O-t-Bu)3: W2(O−t−Bu)6 + EtC≡CC≡CEt → (t−Bu−O)3W≡CC≡W(O−t−Bu)3 + EtC≡CEt This compound, however, does not act as a metathesis catalyst. W2(O−t−Bu)6 also reacts with trans-Pt(C≡CH)2(PMe2Ph)2 to form (t-Bu-O)3W≡C–C≡W(O-t-Bu)3 and trans-(PMe2Ph)2Pt[C2W2(O-t-Bu)5]2.

With nitriles With excess amount of nitrile, N≡W(O-t-Bu)3 is formed along with RC≡CR. The reaction initially gives a 1:1 mixture of the alkylidyne RC≡W(O-t-Bu)3 and nitride N≡W(O-t-Bu)3:

W2(O−t−Bu)6 + RC≡N → RC≡W(O−t−Bu)3 + N≡W(O−t−Bu)3 Although W2(O-t-Bu)6 reacts with nitriles, it doesn’t react with nitrogen (N≡N). When C≡C and C≡N bond both exist, W2(O-t-Bu)6 reacts more rapidly with C≡N than C≡C bond. Here’s an example of W2(O-t-Bu)6 reacting with EtC≡CCN in the presence of quinuclidine:

W2(O−t−Bu)6 +EtC≡CCN + 12L → EtC≡CC≡W(O−t−Bu)3L + N≡W(O−t−Bu)3 On the other hand, the metathesis catalyst MeC≡W(O-t-Bu)3 reacts more rapidly with C≡C than C≡N bond. Similar reaction with EtC≡CCN and quinuclidine produce different product:

W2(O−t−Bu)6 + EtC≡CCN + 12 L → NCC≡W(O−t−Bu)3L + EtC≡CMe

With nitroso W2(O−t−Bu)6 and nitrosobenzene combine to give [W(O-t-Bu)2(NPh)]2(μ-O)(μ-O-t-Bu)2. This reaction undergoes two oxidative additions to form W=N bonds. However, researchers couldn't figure out where the one missing oxygen went. This reaction is the first discovered reaction of a nitroso with metal multiple bonds.

With allenes Allenes react with the ditungsten complex forming adducts, e.g.,

W2(O−t−Bu)6 + H2C=C=CH2 → W2(O−t−Bu)6(HC2=C=CH2) Further reaction with carbon monoxide was also demonstrated.

See also Hexa(tert-butoxy)dimolybdenum(III)

References

Illustrations

Worked examples

Example 1 — a first encounter with Hexa(tert-butoxy)ditungsten(III)

Start with the simplest possible case. Write down what Hexa(tert-butoxy)ditungsten(III) 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 Hexa(tert-butoxy)ditungsten(III) 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 Hexa(tert-butoxy)ditungsten(III) 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 Hexa(tert-butoxy)ditungsten(III)

In research: Hexa(tert-butoxy)ditungsten(III) 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 Hexa(tert-butoxy)ditungsten(III) 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: Hexa(tert-butoxy)ditungsten(III) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alkoxides, Tungsten compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Hexa(tert-butoxy)ditungsten(III) 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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How to study Hexa(tert-butoxy)ditungsten(III) in 20 minutes

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Frequently asked questions

What is Hexa(tert-butoxy)ditungsten(III) in simple terms?

Hexa(tert-butoxy)ditungsten(III) is a coordination complex of tungsten(III). It is one of the homoleptic alkoxides of tungsten.

Why does Hexa(tert-butoxy)ditungsten(III) 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 Hexa(tert-butoxy)ditungsten(III)?

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 Hexa(tert-butoxy)ditungsten(III).