Question

Identify the complex which are expected to be colourless.

• A. $\left[Ti\right(N{O}_3{)}_4{]}^0$
• B. $\left[Cu\right(NCC{H}_3{)}_4{]}^{+}$
• C. $\left[Cr\right(N{H}_3{)}_6]C{l}_3$
• D. $K_{3}V{F}_6$

Answer 1

Answer: (A), (B)

The correct options are
A $\left[Ti\right(N{O}_3{)}_4{]}^0$
B $\left[Cu\right(NCC{H}_3{)}_4{]}^{+}$

The complexes $\left[Ti\right(N{O}_3{)}_4{]}^0$ and $\left[Cu\right(NCC{H}_3{)}_4{]}^{+}$ are expected to be colourless.

(A) In $\left[Ti\right(N{O}_3{)}_4{]}^0$, Ti(IV) ion with electronic configuration $\left[Ar\right]3d^{0}4s^0$ has 0 unpaired electron. Hence, it is expected to be colourless as no d-d transition is possible.

(B) In $\left[Cu\right(NCC{H}_3{)}_4{]}^{+}$, Cu(I) ion with electronic configuration $\left[Ar\right]3d^{10}4s^0$ has 0 unpaired electrons and is expected to be colourless as no d-d transition is possible.

(C) In $\left[Cr\right(N{H}_3{)}_6]C{l}_3$, Cr(III) ion with electronic configuration $\left[Ar\right]3d^{3}4s^0$ contains 3 unpaired electrons and is expected to have violet color due to d-d transitions.

(D) In $K_{3}V{F}_6$, V(III) ion with electronic configuration $3d^{2}4s^0$ has 2 unpaired electrons and is expected to have green colour due to d-d transition.