Question
The $\pi$-complexes are known for transition metals only. Why?
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Answer
Transition metals have vacant d-orbitals in their atoms or ions into which the electron pairs can be donated by ligands containing $\pi$-electrons, e.g., $C_6H_6, CH_2=CH_2$, etc. Thus, $\text{d}$$\pi$ – $\text{p}\pi$ bonding is possible.
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Column I
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Column II
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Methanol
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(ii)
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(b)
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(iv)
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(e)
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