chemistry

Uranium borohydride

Uranium borohydride 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 Uranium borohydride rather than just read about it. In short: Uranium borohydride is the inorganic compound with the empirical formula U(BH4)4. Two polymeric forms are known, as well as a monomeric derivative that exists in the gas phase.

Key takeaways

Uranium borohydride belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Uranium borohydride to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Uranium borohydride from memory before moving on to harder problems.

Reference excerpt

Uranium borohydride is the inorganic compound with the empirical formula U(BH4)4. Two polymeric forms are known, as well as a monomeric derivative that exists in the gas phase. Because the polymers convert to the gaseous form at mild temperatures, uranium borohydride once attracted much attention. It is solid green.

Structure Solid uranium borohydride is a polymer that has a 14-coordinate structure with two tridentate terminal groups and four bidentate bridging groups. The polymer cracks readily to give a homoleptic 12-coordinate coordination complex, with four κ3-BH4− ligands, which envelop the metal, conferring volatility.

Preparation This compound was first prepared by treating uranium tetrafluoride with aluminium borohydride:

UF4 + 2 Al(BH4)3 → U(BH4)4 + 2 Al(BH4)F2 It may also be prepared by the solid-state reaction of uranium tetrachloride with lithium borohydride:

UCl4 + 4 LiBH4 → U(BH4)4 + 4 LiCl Although solid U(BH4)4 is a polymer, it undergoes cracking, converting to the monomer. The related methylborohydride complex U(BH3CH3)4 is monomeric as a solid and hence more volatile.

History During the Manhattan Project, the need arose to find volatile compounds of uranium suitable for use in the diffusion separation of uranium isotopes. Uranium borohydride is, after uranium hexafluoride, the most volatile compound of uranium known with a vapor pressure of 4 mmHg (530 Pa) at 60 °C. Uranium borohydride was discovered by Hermann Irving Schlesinger and Herbert C. Brown, who also discovered sodium borohydride. Uranium hexafluoride is corrosive, which led to serious consideration of the borohydride. However, by the time the synthesis method was finalized, the problems related to uranium hexafluoride were solved. Borohydrides are nonideal ligands for isotope separations, since there are isotopes of boron that occur naturally in high abundance: 10B (20%) and 11B (80%), while fluorine-19 is the only isotope of fluorine that occurs in nature in more than trace quantities.

References

Illustrations

Worked examples

Example 1 — a first encounter with Uranium borohydride

Start with the simplest possible case. Write down what Uranium borohydride 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 Uranium borohydride 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 Uranium borohydride 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 Uranium borohydride

In research: Uranium borohydride 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 Uranium borohydride 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: Uranium borohydride is common in secondary-school and first-year university syllabi. It links to neighbouring topics Borohydrides, Coordination polymers, Inorganic polymers, so understanding it makes those chapters shorter.
In everyday life: Look for Uranium borohydride 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 Uranium borohydride in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Uranium borohydride means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Uranium borohydride out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Uranium borohydride in simple terms?

Uranium borohydride is the inorganic compound with the empirical formula U(BH4)4. Two polymeric forms are known, as well as a monomeric derivative that exists in the gas phase.

Why does Uranium borohydride 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 Uranium borohydride?

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 Uranium borohydride.