The complex sodium pentacyanonitrosylferrate(II) is commonly known as sodium nitroprusside. Let be t — Coordination Compounds Chemistry Question
Question
The complex sodium pentacyanonitrosylferrate(II) is commonly known as sodium nitroprusside. Let $x$ be the number of sodium ions in the formula, and $y$ be the coordination number of the central iron atom. Calculate the value of $(x + y)$.
💡 Solution & Explanation
The central metal is $Fe(II)$ with an oxidation state of $+2$. The ligands are five cyanido ($CN^-$) and one nitrosyl. In this specific complex, nitrosyl acts as the positive nitrosonium ion ($NO^+$). Thus, the charge on the coordination sphere is $+2 (\text{from } Fe) + 5(-1) (\text{from } CN) + 1 (\text{from } NO^+) = -2$. The sphere is $[Fe(CN)_5NO]^{2-}$. To balance this, 2 sodium ions ($Na^+$) are needed, giving $Na_2[Fe(CN)_5NO]$. Therefore, $x = 2$. The coordination number $y$ is $5 + 1 = 6$. The sum $(x + y) = 2 + 6 = 8$.