What’s the difference between a coordination entity and a coordination sphere? Are they the same? Here in my book, the same example is given for both the coordination entity and coordination sphere.

(a) Coordination entity
A coordination entity constitutes a central metal atom or ion bonded to a fixed number of ions or molecules. For example, $\ce{[CoCl3(NH3)3]}$ is a coordination entity in which the cobalt ion is surrounded by three ammonia molecules and three chloride ions. Other examples are $\ce{[Ni(CO)4]}$, $\ce{[PtCl2(NH3)2]}$, $\color{red}{\ce{[Fe(CN)6]^{4–}}}$, $\ce{[Co(NH3)6]^{3+}}$.

(e) Coordination sphere
The central atom/ion and the ligands attached to it are enclosed in square bracket and is collectively termed as the coordination sphere. The ionisable groups are written outside the bracket and are called counter ions. For example, in the complex $\ce{K4[Fe(CN)6]}$, the coordination sphere is $\color{red}{\ce{{[Fe(CN)_6]^{4–}}}}$ and the counter ion is $\ce{K+}$.

Please help.

Source: http://ncert.nic.in/ncerts/l/lech109.pdf

Section 9.2 Definitions of Some Important Terms Pertaining to Coordination Compounds

Page no. 240-241

  • $\begingroup$ There are also coordination moiety, coordination shell and coordination environment terms. $\endgroup$
    – andselisk
    Nov 2, 2017 at 5:06

1 Answer 1


Coordination entity is the part of complex compound having central atom surrounded with the number of secondary linkage. But,if this entity is written along with charge on it ,then it is called coordination sphere For example $\ce{[Fe(CN)6]^{4-}}$ is a coordination sphere while $\ce{Fe(CN)6}$ is the coordination entity


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