chemistry

Tetrakis(1-norbornyl)cobalt(IV)

Tetrakis(1-norbornyl)cobalt(IV) 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(1-norbornyl)cobalt(IV) rather than just read about it. In short: Tetrakis(1-norbornyl)cobalt(IV) is an air-sensitive organometallic compound of cobalt. It was first synthesized by Barton K.

Key takeaways

Tetrakis(1-norbornyl)cobalt(IV) belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Tetrakis(1-norbornyl)cobalt(IV) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Tetrakis(1-norbornyl)cobalt(IV) from memory before moving on to harder problems.

Reference excerpt

Tetrakis(1-norbornyl)cobalt(IV) is an air-sensitive organometallic compound of cobalt. It was first synthesized by Barton K. Bower and Howard G. Tennent in 1972 and is one of few compounds in which cobalt has a formal oxidation state of +4.

Preparation Tetrakis(1-norbornyl)cobalt(IV) is formed the reaction of CoCl2•THF with 1-norbornyllithium (norLi) in n-pentane under an inert atmosphere. The cobalt(II) chloride-THF adduct is prepared from Soxhlet extraction of anhydrous CoCl2 with THF, and the organolithium reagent is prepared from the reaction between 1-chloro-norbornane and lithium metal in a solvent such as pentane:

2 CoCl2•THF + 4 norLi → [Co(nor)4] + Co + 4 LiCl + 2 THF

The compound can then be purified by recrystallization.

Properties The complex is a thermally stable homoleptic tetraorganylcobalt(IV) complex with exclusively σ-bonding ligands. It was the first low-spin complex with tetrahedral geometry to be isolated.

Stability The exceptional stability of the complex is in large part due to its inability to undergo either α- or β-hydride elimination. The α-position of the metal (corresponding to the 1-position of the norbornyl ligand) has no more hydrogen atoms, while hydride elimination from the β-position would yield an energetically unfavorable double bond on a bridgehead atom (Bredt's rule). Moreover, the bulky norbornyl ligands sterically shield the central atom, hindering ligand substitutions as well as homolysis. The rare d5 low-spin configuration in a tetrahedral ligand field is possible because the ligand is so strongly σ-donating that the gap between the e und t2 orbitals is raised sufficiently to overcome the spin pairing energy. The resulting configuration is e4t21, with magnetic measurements showing paramagnetism consistent with only one unpaired electron.

Cobalt(III) and cobalt(V) derivatives The reaction between CoCl2•THF and 1-norbornyllithium (norLi) also allows the formation of a cobalt(III) complex: if a mixture of diethyl ether and THF is used as the solvent in place of n-pentane, the resulting disproportionation reaction affords the complex tetrakis(1-norbornyl)cobaltate(III), which crystallizes out of solution with solvated lithium counterions, along with elemental cobalt.

3 CoCl 2 ⋅ THF + 8 norLi + 5 THF → Et 2 O / THF 2 [ Li ( THF ) 4 ] [ Co ( nor ) 4 ] + Co + LiCl {\displaystyle {\ce {3 {CoCl2.THF}+ 8 {norLi}+ 5 {THF}->[{\ce {Et2O/THF}}] 2 {[Li(THF)4][Co(nor)4]}+ {Co}+ LiCl}}}

The compound is air-sensitive, has a green color and is paramagnetic, with two unpaired electrons, again indicating a low-spin tetrahedral configuration (d6, e4t22). The corresponding cobalt(V) complex is prepared by oxidizing tetrakis(1-norbornyl)cobalt(IV) with Ag[BF4] in THF and crystallizes with tetrafluoroborate as the counterion.

Co(nor)4 + AgBF4 → [Co(nor)4]BF4 + Ag This complex :[Co(nor)4]+ is the first cobalt(V) complex to be isolated. Again the configuration is low-spin (d4, e4t20).

Illustrations

Worked examples

Example 1 — a first encounter with Tetrakis(1-norbornyl)cobalt(IV)

Start with the simplest possible case. Write down what Tetrakis(1-norbornyl)cobalt(IV) 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(1-norbornyl)cobalt(IV) 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(1-norbornyl)cobalt(IV) 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(1-norbornyl)cobalt(IV)

In research: Tetrakis(1-norbornyl)cobalt(IV) 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(1-norbornyl)cobalt(IV) 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(1-norbornyl)cobalt(IV) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Norbornanes, Organocobalt compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Tetrakis(1-norbornyl)cobalt(IV) 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 Tetrakis(1-norbornyl)cobalt(IV) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tetrakis(1-norbornyl)cobalt(IV) 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.
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Frequently asked questions

What is Tetrakis(1-norbornyl)cobalt(IV) in simple terms?

Tetrakis(1-norbornyl)cobalt(IV) is an air-sensitive organometallic compound of cobalt. It was first synthesized by Barton K.

Why does Tetrakis(1-norbornyl)cobalt(IV) 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(1-norbornyl)cobalt(IV)?

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(1-norbornyl)cobalt(IV).