Number of complexes which will exhibit synergic bonding amongst, $[\mathrm{Cr}(\mathrm{CO})_{6}]$, $[\mathrm{Mn}(\mathrm{CO})_{5}]$ and $[\mathrm{Mn}_{2}(\mathrm{CO})_{10}]$ is ______.

JEE Main · 2022 · 28 Jun 2022 · Shift 1 · Coordination Compounds

Number of complexes which will exhibit synergic bonding amongst,

[Cr (CO)_{6}]

[Mn (CO)_{5}]

and

[Mn_{2} (CO)_{10}]

is ______.

Answer: 3

Solution

Synergic bonding occurs in metal carbonyl complexes where CO acts as both a σ-donor (through the lone pair on carbon) and a π-acceptor (through back-donation from filled metal d-orbitals to empty π* orbitals of CO).

All three given complexes are metal carbonyls:

$[Cr (CO)_{6}]$ — chromium hexacarbonyl
$[Mn (CO)_{5}]$ — manganese pentacarbonyl (radical/fragment)
$[Mn_{2} (CO)_{10}]$ — dimanganese decacarbonyl

All carbonyl complexes exhibit synergic bonding. Therefore, the answer is 3.

JEE Main · 2022 · 28 Jun 2022 · Shift 1 · Integer answer

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