Coordination Compounds

Coordination Compounds


Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.


Electronic configuration of Ti3+ is [Ar]3d2 4s2. Metal ions usually form hexacoordinated complexes with water molecules.  According to Crystal field theory [Ti(H2O)6]+3, Ti3+ ion has outer shell configuration ast2g1eg0 There is an electron free to jump between energy level. Thus Ti3+ ions selectively absorb certain colours, hence its solution is coloured.

SC3+, on the other hand, has an empty d orbital; the [Sc(H2O)6]+3 complex has no electrons in T2g or eg orbitals. Hence SC3+ is colourless in aqueous solution.

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