Coordination Compounds Test - 7

Geometrical isomerism arises in heterolyptic complexes due to different possible geometric arrangements of the ligands. In [Co(en)₃]³⁺ all ligands are same i.e. ethane-1,2-diamine. It is symmetrical so it does not show geometrical isomerism.

EDTA (ethylenediaminetetraacetato) is a hexadentate ligand and it forms stable chelate complex with given metal ions. The selective estimation of these ions can be done due to difference in stability constants of complexes of these ions with EDTA.

Complexes in which the central metal is bound to only one kind of donor groups are called homolyptic complexes. [Cu(NH_{​​​​​3})₆]⁺² is a homolyptic complex because in this only ammonia group is the donor group bound to Cu⁺².

Ammonia forms stable complex with Cu²⁺ which is dark blue in colour. So the blue colour of CuSO ₄ solution becomes darker when ammonia is added to it.
Cu⁺² + 4NH₃ →→ [Cu(NH₃)₄]⁺²

According to Werner’s theory, secondary valences are non-ionisable and are satisfied by neutral molecules or negative ions. Secondary valence is equal to the coordination number and is fixed for a metal.

Given complex can be written as K₃[CoF₆]. There are 3 Potassium ions K⁺ means an overall +3 charge on cations and so the charge on the complex anion is -3. Each F^- ligand has -1 charge so there is a total of -6 charge on ligands. Let oxidation state of Co (Z=27) be x

x + ( -6) = -3
x = -3 + 6 = +3

So oxidation state of Co=+3 and its electronic configuration is 1s²2s²2p⁶3s²3p⁶3d⁶ . Since its a high spin complex means there is no pairing of electrons in 3d subshell. Coordination number of Co is 6 as there are 6 ligands bound to it, so this octahedral complex has hybridization sp³d².

Tetraaminecopper(II) ion is square planar. Square planar complexes have dsp^{​​​​2} hybridisation. So hybridization is dsp².

This is a double salt so its name is written in alphabetical order and the number of molecules of water of crystallisation are mentioned in the end. So the name is aluminium potassium sulphate dodecahydrate.

This is a double salt so its IUPAC name is written in alphabetical order and number of the molecules of water of crystallisation is mentioned in the end. So the name is ammonium ferrous sulphate hexahydrate.