For typical Fischer and Schrock carbenes, consider the following statements
\[ \begin{array}{l} \text{A. Oxidation state of metal is low in Fischer carbene and high in Schrock carbene} \\ \text{B. Auxilliary ligands are } \pi\text{-acceptor in Fischer carbene and non } \pi \text{ acceptor in Schrock carbene} \\ \text{C. Substituents on carbene carbon are non } \pi \text{ donor in Fischer carbene and } \pi \text{ donor in Schrock carbene} \\ \text{D. Carbene carbon is electrophilic in Fischer carbene and nucleophilic in Schrock carbene} \end{array} \]
The correct statements are
(a)A, B and C
(b)A, B and D
(c)B, C and D
(d)A, C and D
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
Fischer carbenes have low-valent metals, π-acceptor co-ligands, π-donor substituents (OR, NR₂) and an electrophilic carbene carbon. Schrock carbenes are the opposite on each count. C has the substituents reversed. A, B and D (b).