The hapticity of cycloheptatriene, $\left(\mathrm{C}_{7} \mathrm{H}_{8}\right)$, in $\mathrm{Mo}\left(\mathrm{C}_{7} \mathrm{H}_{8}\right)(\mathrm{CO})_{3}$ is ____
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.
Explanation
Answer: 6 (η⁶) — Mo(0) has 6 electrons and three CO give 6, so an η⁶-triene (6 electrons) is needed to reach 18.