Q52 · CSIR NET Chemistry, June 2012
Paper: CSIR NET June 2012 · Subject: Inorganic Chemistry · Chapter: Organometallic Compounds · Topic: Metal Carbonyls · Marks: 2 · Difficulty: Easy
The reaction $3\left[\mathrm{Rh}_{4}(\mathrm{CO})_{12}\right] \rightarrow 2\left[\mathrm{Rh}_{6}(\mathrm{CO})_{16}\right]+4 \mathrm{CO}\left[25^{\circ} \mathrm{C}, 500 \mathrm{atm} \mathrm{CO}\right]$ is:
(a)Exothermic as more metal-metal bonds are formed.
(b)Endothermic as stronger metal-carbonyl bonds are cleaved while weaker metal-metal bonds are formed.
(c)Is entropicallyfavorable but enthalpicallyunfavorable such that ( $\Delta \mathrm{G}=0$ )
(d)Thermodynamically unfavourable $(\Delta \mathrm{G}>0)$.
Answer
Answer: B ✓ checked by 4AB · confidence medium
Explanation
Converting Rh₄(CO)₁₂ to Rh₆(CO)₁₆ breaks strong Rh–CO bonds and forms weaker Rh–Rh bonds, so it is endothermic; it is driven by the entropy of the released CO at high temperature.
Study loop for Organometallic Compounds