chemistry

Osmium compounds

Osmium compounds 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 Osmium compounds rather than just read about it. In short: Osmium compounds are compounds containing the element osmium (Os). Osmium forms compounds with oxidation states ranging from −2 to +8.

Key takeaways

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

Reference excerpt

Osmium compounds are compounds containing the element osmium (Os). Osmium forms compounds with oxidation states ranging from −2 to +8. The most common oxidation states are +2, +3, +4, and +8. The +8 oxidation state is notable for being the highest attained by any chemical element aside from iridium's +9 and is encountered only in xenon, ruthenium, hassium, iridium, and plutonium. The oxidation states −1 and −2 represented by the two reactive compounds Na2[Os4(CO)13] and Na2[Os(CO)4] are used in the synthesis of osmium cluster compounds.

Oxides

Osmium tetroxide is the most notable compound of osmium, having many uses. The name "osmium" even derives from Greek "ὀσμή, osme, 'smell'" because of the smell of osmium tetroxide. It also has a number of unusual properties, one being that the solid is volatile. Its volatility, along with its strong oxidizing power, is the origin of its quite serious toxicity - inhalation provides a very effective route for the compound to react with tissue. The compound is colourless, but most samples appear yellow. This is most likely due to the presence of the impurity OsO2, which is yellow-brown in colour. In biology, its property of binding to lipids has made it a widely used stain in electron microscopy. OsO4 is formed slowly when osmium powder reacts with O2 at ambient temperature. Reaction of bulk solid requires heating to 400 °C.

Os + 2 O 2 → Δ T OsO 4 {\displaystyle {\ce {Os + 2O2 ->[\Delta T] OsO4}}}

OsO4 is a Lewis acid and a mild oxidant. It reacts with alkaline aqueous solution to give the perosmate anion OsO4(OH)2−2. This species is easily reduced to osmate anion, OsO2(OH)2−4. When the Lewis base is an amine, adducts are also formed. Thus OsO4 can be stored in the form of osmeth, in which OsO4 is complexed with hexamine. Osmeth can be dissolved in tetrahydrofuran (THF) and diluted in an aqueous buffer solution to make a dilute (0.25%) working solution of OsO4. With tert-BuNH2, the imido derivative is produced:

OsO 4 + Me 3 CNH 2 ⟶ OsO 3 ( NCMe 3 ) + H 2 O {\displaystyle {\ce {OsO4 + Me3CNH2 -> OsO3(NCMe3) + H2O}}}

Similarly, with NH3 one obtains the nitrido complex:

OsO 4 + NH 3 + KOH ⟶ K [ Os ( N ) O 3 ] + 2 H 2 O {\displaystyle {\ce {OsO4 + NH3 + KOH -> K[Os(N)O3] + 2 H2O}}}

The [Os(N)O3]− anion is isoelectronic and isostructural with OsO4. OsO4 is very soluble in tert-butyl alcohol. In solution, it is readily reduced by hydrogen to osmium metal. The suspended osmium metal can be used to catalyze hydrogenation of a wide variety of organic chemicals containing double or triple bonds.

OsO 4 + 4 H 2 ⟶ Os + 4 H 2 O {\displaystyle {\ce {OsO4 + 4 H2 -> Os + 4 H2O}}}

OsO4 undergoes "reductive carbonylation" with carbon monoxide in methanol at 400 K and 200 sbar to produce the triangular cluster Os3(CO)12:

3 OsO 4 + 24 CO ⟶ Os 3 ( CO ) 12 + 12 CO 2 {\displaystyle {\ce {3 OsO4 + 24 CO -> Os3(CO)12 + 12 CO2}}}

Osmium dioxide is another known oxide of osmium, which can be obtained by the reaction of osmium with a variety of oxidizing agents, including, sodium chlorate, osmium tetroxide, and nitric oxide at about 600 °C. It does not dissolve in water, but is attacked by dilute hydrochloric acid. The crystals have rutile structure. Unlike osmium tetroxide, OsO2 is not toxic.

Halides

Fluorides

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Osmium compounds

Start with the simplest possible case. Write down what Osmium compounds 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 Osmium compounds 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 Osmium compounds 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 Osmium compounds

In research: Osmium compounds 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 Osmium compounds 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: Osmium compounds is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chemical compounds by element, Osmium, Osmium compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Osmium compounds 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 Osmium compounds in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Osmium compounds 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 Osmium compounds out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Osmium compounds in simple terms?

Osmium compounds are compounds containing the element osmium (Os). Osmium forms compounds with oxidation states ranging from −2 to +8.

Why does Osmium compounds 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 Osmium compounds?

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 Osmium compounds.