question_answer

Which of the following complexes has minimum magnitude of Ape?

A)  \[{{[Cr{{(CN)}_{6}}]}^{3-}}\]      

B)  \[{{[Co{{(NH)}_{3}})}_{6}}{{]}^{3+}}\]

C)  \[{{[CoCl]}_{6}}{{]}^{3-}}\]

D)  \[{{[Cr{{({{H}_{2}}O)}_{6}}]}^{3+}}\]

Correct Answer: C

Solution :

[a] In \[{{[Cr{{(CN)}_{6}}]}^{3-}}\] and \[{{[Cr{{({{H}_{2}}O)}_{6}}]}^{3+}}\] both, Cr is present as \[C{{r}^{3+}}\]. \[CFSE=-0.4\times 3=-1.2\] [b] In \[{{[Co{{(N{{H}_{3}})}_{6}}]}^{3+}}\], Co is present as \[C{{o}^{3+}}\] \[CFSE=-0.4\times 6\]= - 2.4 [c]  In \[{{[CoC{{l}_{6}}]}^{3-}}Co\], is again present as \[C{{o}^{2+}}\] \[CFSE=-0.4\times 4+0.6\times 2=-1.6+1.2\] = - 0.4 Thus, the magnitude of \[{{\Delta }_{o}}\] is minimum for \[{{[CoC{{l}_{6}}]}^{3-}}\]-.