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Question: Which of the following has the longest \[C - O\] bond length? (Free \[C - O\] bond length in \[CO\] ...

Which of the following has the longest COC - O bond length? (Free COC - O bond length in COCO is1.128A{1.128^ \circ }A)
A. Ni(CO)4Ni{(CO)_4}
B. [Co(CO)4]8{[Co{(CO)_4}]^8}
C. [Fe(CO)4]2{[Fe{(CO)_4}]^{2 - }}
D. [Mn(CO)6]+{[Mn{(CO)_6}]^ + }

Explanation

Solution

The higher the oxidation state of the central metal atom, the shorter will be the bond length of COC - O bond as the bond will be strong. The COC - O bond is firmly captivated towards oxygen. Bond lengths for paraffinic COC - O bonds are in the scope of 143 pm – not exactly those of C–N or C–C bonds. The COC - O bond quality is additionally bigger than C–N or C–C. For instance, bond qualities are 91 kilocalories (380 kJ)/mol\left( {380{\text{ }}kJ} \right)/mol (at 298 K) in methanol, 87 kilocalories (360 kJ)/mol\left( {360{\text{ }}kJ} \right)/mol in methylamine, and 88 kilocalories (370 kJ)/mol\left( {370{\text{ }}kJ} \right)/mol in ethane.

Step by step answer: According to our question, correct answer is [Fe(CO)4]2{[Fe{(CO)_4}]^{2 - }}as it has longest COC - O bond length among the given complexes. In its typical expression, the COC - O bond length is simply 1.43A˙1.43\dot A, when present in oxatriquinane in any case, the bond length (otherwise called bond separation) is normally extended to 1.54A˙1.54\dot A. Bond length is the normal separation between the cores of two ions that are reinforced together in a solitary atom.
In Ni(CO)4Ni{(CO)_4}​⇒ Oxidation state of NiNi = 0
In [Co(CO)4]8{[Co{(CO)_4}]^8} ⇒ Oxidation state of CoCo= 0
In [Fe(CO)4]2{[Fe{(CO)_4}]^{2 - }} ⇒ Oxidation state of FeFe = −2
In [Mn(CO)6]+{[Mn{(CO)_6}]^ + } ⇒ Oxidation state of MnMn = +1
The order of bond length of the given complexes is: [Mn(CO)6]+<Ni(CO)4<[Co(CO)4]8<[Fe(CO)4]2{[Mn{(CO)_6}]^ + } < Ni{(CO)_4} < {[Co{(CO)_4}]^8} < {[Fe{(CO)_4}]^{2 - }}

Hence the correct option is (C).

Note: Due to back bonding between metal-carbon bonds, the length of COC - O increases. So bond length is higher. Carbon monoxide (CO) is a lackluster, unscented, and boring combustible gas that is marginally less thick than air. It is harmful to creatures that utilization hemoglobin as an oxygen transporter (both invertebrate and vertebrate) when experienced in focuses above around 35 ppm, in spite of the fact that it is additionally delivered in typical creature digestion in low amounts, and is thought to have some ordinary organic capacities. In the environment, it is spatially factor and fleeting, having a function in the arrangement of ground-level ozone.