C

Coordination Sphere

[MLₙ]^x (inner sphere)
Quick Reference
Formula / Notation[MLₙ]^x (inner sphere)
Also Known AsInner coordination sphere, first coordination sphere, inner sphere

What is Coordination Sphere?

The coordination sphere of a complex consists of the central metal atom or ion together with all ligands directly bonded to it. It is usually enclosed in square brackets in the formula of a coordination compound, for example [Co(NH₃)₆] in [Co(NH₃)₆]Cl₃. Species outside the coordination sphere are counterions and are not directly bonded to the metal.

Formula & Notation

[MLₙ]^x (inner sphere)

Other Names / Synonyms: Inner coordination sphere, first coordination sphere, inner sphere

Properties & Characteristics

The coordination sphere refers to the central metal atom and all ligands directly bonded to it in a coordination compound, enclosed in square brackets in the formula. Ligands in the coordination sphere are held by coordinate bonds and behave as a unit. Counter-ions outside the coordination sphere are ionically associated. For example, in [Co(NH₃)₅Cl]Cl₂, the coordination sphere is [Co(NH₃)₅Cl]²⁺.

Uses & Applications

Distinguishing inner and outer sphere components is essential for determining the formula, charge, and conductivity of coordination compounds, for writing dissociation equations, and for understanding substitution reaction mechanisms (inner sphere vs. outer sphere electron transfer).

Safety Information

Ligands within the coordination sphere may be tightly bound and not freely released (low toxicity from that ligand). However, upon complex decomposition in biological systems, toxic ligands can be released. The stability constant of the complex governs this risk.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Coordination Sphere
Formula [MLₙ]^x (inner sphere)
Synonyms Inner coordination sphere, first coordination sphere, inner sphere

Frequently Asked Questions

The coordination sphere of a complex consists of the central metal atom or ion together with all ligands directly bonded to it. It is usually enclosed in square brackets in the formula of a coordination compound, for example [Co(NH₃)₆] in [Co(NH₃)₆]Cl₃. Species outside the coordination sphere are counterions and are not directly bonded to the metal.

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