Question

Which of following coordinate complexes is an exception to $EAN$ rule ? (Given At. No. Pt = 78, Fe = 26, Zn = 30, Cu = 29)

• A. $[Pt (NH_3)_6]^{4+}$
• B. $[Fe (CN_3)_6]^{4-}$
• C. $[Zn (NH_3)_4]^{2+}$
• D. $[Cu (NH_3)_4]^{2+}$

Answer 1

Answer: (D)

$[Cu (NH_3)_4]^{2+}$

Answer 2

$\left[ Cu \left( NH _{3}\right)_{4}\right]^{2+}$ is an exception to EAN rule.
$EAN = Z - X + Y$
$EAN =29-2+8=35$
The atomic number of nearest noble gas $( Kr )$ is $36$ .
Note:
${\left[ Pt \left( NH _{3}\right)_{6}\right]^{4+}}$
$EAN =78-4+12=86$
The atomic number of nearest noble gas $( Rn )$ is $86$ .
$\left[ Fe ( CN )_{6}\right]^{4-}$
$EAN =26-2+12=36$
The atomic number of nearest noble gas $( Kr )$ is $36$ .
$\left[ Zn \left( NH _{3}\right)_{4}\right]^{2+}$
$EAN =30-2+8=36$
The atomic number of nearest noble gas $( Kr )$ is $36 .$