Pi bonds, if formed between the
ligand and the central atom/ion, are not counted for this purpose (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 K4[Fe(CN)6],
the coordination sphere is [Fe(CN)6]
4– and the counter ion is K
+