chemistry

Symbiosis (chemical)

Symbiosis (chemical) 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 Symbiosis (chemical) rather than just read about it. In short: The biological term symbiosis was first used in chemistry by C. K.

Key takeaways

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

Reference excerpt

The biological term symbiosis was first used in chemistry by C. K. Jørgensen in 1964, to refer to the process by which a hard ligand on a metal predisposes the metal to receive another hard ligand rather than a soft one. Two superficially antithetical phenomena occur: symbiosis and antisymbiosis.

Chemical antisymbiosis This is found principally with soft metals. Two soft ligands in mutual trans position will have a destabilizing effect on each other. The effect is also found with borderline metals in the presence of high trans effect ligands. For example the selenocyanate ion trans to the soft carbon dioxide in trans-Rh(PPh3)2(CO)(NCSe) bonds via the nitrogen, the harder of its two donors. The phenomenon may be explained in terms of a trans influence:

“With two π-acid ligands in mutual trans positions at a class-b metal, there would be a destabilizing competition for the dπ electrons on the metal. A π-acid bonded to a soft metal thus makes a metal a harder Lewis acid. Similarly a soft σ-donor will tend to polarize the electron density on a soft metal, causing it to favour an electrovalently bonded ligand in the trans position.”

Chemical symbiosis This effect occurs with class-a metals such as iron(II). The Cyclopentadienyl complex (C5H5)Fe(CO)2(SCN) is an example of chemical symbiosis. The cyclopentadienyl directs the thiocyanate to bond through its softer Sulphur donor. A more definitive example are the halopentamminocobalt(III) ions, Co(NH3)5X2+, which are more stable when the halogen, X, is fluoride than with iodide, and the halopentcyanocobalt(III) ions, Co(CN)5X3−, which are most stable when the halogen is iodine.

“Hard bases (electronegative donor atoms) retain their valence (outer shell) electrons when attached to a given central metal ion, thus enabling the metal ion to retain more of its positive charge, making it a hard Lewis acid. With soft bases the central metal atom is made a softer Lewis acid, because the metal’s positive charge is reduced by delocalization of electron density from the ligand into the ligand-metal bond. But we have the distinction that with a class-a metal there is little concomitant polarization of the electron density away from the trans position of the metal. In addition, symbiosis, unlike antisymbiosis, is probably not specifically trans directional, and is just as effective in, say, tetrahedral complexes.”

References

Worked examples

Example 1 — a first encounter with Symbiosis (chemical)

Start with the simplest possible case. Write down what Symbiosis (chemical) 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 Symbiosis (chemical) 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 Symbiosis (chemical) 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 Symbiosis (chemical)

In research: Symbiosis (chemical) 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 Symbiosis (chemical) 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: Symbiosis (chemical) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Coordination chemistry, so understanding it makes those chapters shorter.
In everyday life: Look for Symbiosis (chemical) 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 Symbiosis (chemical) in 20 minutes

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

Frequently asked questions

What is Symbiosis (chemical) in simple terms?

The biological term symbiosis was first used in chemistry by C. K.

Why does Symbiosis (chemical) 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 Symbiosis (chemical)?

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 Symbiosis (chemical).