Identify the homoleptic complex(es) that is/are low spin. (A) [Fe(CN)5NO]^2- (B) [CoF6]^3-

Question

Identify the homoleptic complex(es) that is/are low spin.

(A) \(\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NO}\right]^{2-}\)

(B) \(\left[\mathrm{CoF}_{6}\right]^{3-}\)

(C) \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}\)

(D) \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}\)

(E) \(\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}\)

Choose the correct answer from the options given
below:

(1) (B) and (E) only

(2) (A) and (C) only

(3) (C) and (D) only

(4) (C) only

Answer 1

Correct option is: (3) (C) and (D) only

(A)  \(\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NO}\right]^{-2} \rightarrow Heteroleptic, \mathrm{Fe}^{+2}, 3 \mathrm{~d}^{6},\)

\(\mathrm{t}_{2 \mathrm{~g}}{ }^{6} \mathrm{e}_{\mathrm{g}}{ }^{0}, \mathrm{~d}^{2} \mathrm{sp}^{3}, \text{Low spin (3d series + SFL)}\)

(B)  \(\left[\mathrm{CoF}_{6}\right]^{-3} \rightarrow Homoleptic, \mathrm{sp}^{3} \mathrm{~d}^{2}, High\ spin,\)

\( \mathrm{Co}^{+3}, 3 \mathrm{~d}^{6}(3 \mathrm{~d} \ series +WFL)\)

(C)  \( \left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{-4} \rightarrow Homoleptic\)

\( \mathrm{Fe}^{+2}, 3 \mathrm{~d}^{6}, \mathrm{~d}^{2} \mathrm{sp}^{3}, \mathrm{t}_{2 \mathrm{~g}}{ }^{6} \mathrm{eg}^{0}\ Low spin\)

\( (\text{3d series} + SFL )\)

(D)  \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{+3} \rightarrow Homoleptic, \mathrm{Co}^{+3} 3 \mathrm{~d}^{6}, \mathrm{~d}^{2} \mathrm{sp}^{3},\)

\( \mathrm{t}_{2 \mathrm{~g}}{ }^{6} \mathrm{eg}^{0}, Low\ spin (3d\ series + SFL )\)

(E) \(\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{+2} \rightarrow Homoleptic\)

\( \mathrm{Cr}^{+2} 3 \mathrm{~d}^{4}, \mathrm{~d}^{2} \mathrm{sp}^{3}, High\ spin \ \mathrm{t}_{2 \mathrm{~g}}{ }^{3} \mathrm{e}_{\mathrm{g}}{ }^{1}\)

\( (\text{3d series} + WFL)\)