Tag: metal carbonyls

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Questions Related to metal carbonyls

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

$Cr - C$ bond in the compound $[Cr(CO) _6]$ shows $\pi$ - character due to :

  1. covalent bonding

  2. coordinate bonding

  3. synergic bonding

  4. ionic bonding
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  1. Synergic bonding is the description of the bonding of $\pi$ - configuration ligands to the transition metal which involves donation of electrons through back bonding.
    2. Mainly carbonyl ligands in complex compounds involves in this type of bonding.
Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

$\left[ {C{O _2}{{(CO)} _8}} \right]$ displays:

  1. One-Co Co bond, six terminal CO and two bridging CO

  2. One-Co Co bond, four terminal CO and four bridging CO

  3. No-Co Co bond, six terminal CO and two bridging CO

  4. No-Co Co bond, four terminal CO and four bridging CO
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dicobalt octacarbonyl, Co2(CO)8, in its solid state exists as a bridged structure containing one metal-metal bond (Co-Co), six terminal CO groups, and two bridging CO groups.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Which of the following factors tends to increase the stability of metal ion complexes?

  1. Higher ionic radius of the metal ion

  2. Higher charge/size ratio of the metal ion

  3. Lower ionisation potential of the metal ion

  4. Lower basicity of the ligand
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
For a given ligand, the stability of complexes of metallic ions having the same charge on them decreases with the increase of the size of the central metal ions. Again if the charge of central metal ion is more and the site is small, then the stability of the complex is more. Higher charge/size ratio of metal ion i.e highly charged cation and the smaller cation can form more stable complexes.
Answer will be B.
Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Consider the following complexes $[V(CO) _6]^-,[Cr(CO) _6]$ and $[Mn(CO) _6]^+$. Then incorrect statement(s) about metal carbonyls is /are

  1. 'C-O' bond is strongest in the cation and weakest in the anion

  2. 'C-O' bond order is less in the cation than in anion

  3. 'C-O' bond longer in the cation than in anion or neutral carbonyl

  4. 'M-C' bond order is higher in the carbon than in anionic or neutral carbonyl.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In metal carbonyls, as the negative charge on the complex increases, back-bonding from metal to CO increases, strengthening the M-C bond and weakening the C-O bond. Thus, the C-O bond is weakest in the anion and strongest in the cation.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

If CO ligands are substituted by NO in respective neutral carbonyl compounds then which of the following will not be correct formula?

  1. $Cr(CO) _3(NO) _2$
  2. $Fe(CO) _2(NO) _2$
  3. $Cr(NO) _4$
  4. $Ni(CO) _2(NO) _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using the 18-electron rule, Cr(CO)6 has 18 electrons. Substituting CO (2e) with NO (3e) changes the count. Cr(CO)3(NO)2 would have 6 + 6 + 6 = 18 electrons. However, Cr(NO)4 is not a stable neutral carbonyl-like complex following this substitution pattern.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

The V-C distance in ${\text{V}}{\left( {{\text{CO}}} \right) _{\text{6}}}\;{\text{and}}\;\left[ {{\text{V}}{{\left( {{\text{CO}}} \right)} _{\text{6}}}} \right]$ are respectively (in pm) -

  1. 200, 200

  2. 193, 200

  3. 200, 193

  4. 193, 193
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In V(CO)6 (neutral), the V-C bond is longer due to less back-bonding compared to the [V(CO)6]- anion, where increased back-bonding strengthens the M-C bond and shortens the distance.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Which of the following statement is correct regarding the compound ${\text{''}}\left[ {{{\left( {{\text{CO}}} \right)} _{\text{3}}}{\text{Fe}}{{\left( {{\text{CO}}} \right)} _{\text{3}}}{\text{Fe}}{{\left( {{\text{CO}}} \right)} _{\text{3}}}} \right]{\text{'}}$

  1. The ${{\text{d}} _{{\text{C - O}}}}$ (bridging) is greater than ${{\text{d}} _{{\text{C - O}}}}$ (terminal)

  2. The bond order of bridging C-O bond is greater than that of terminal C-O bond

  3. The E.A.N. value of each Fe-atom is 35

  4. the oxidation state of Fe in this complex is (-1)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In Fe3(CO)12, bridging CO ligands have a lower bond order than terminal CO ligands because they participate in more extensive back-bonding, resulting in a longer C-O bond length for bridging ligands.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Which of the following statement is correct regarding metal carbonyl?

  1. In ${Mn} _{2}{(CO)} _{10}$ bond order of $Mn-Mn$ is $0$
  2. In ${Fe} _{2}{(CO)} _{9}$ bond order of $Fe-Fe$ is $1$
  3. In $Ni{(CO)} _{4}$, all bond length are same
  4. $Fe{(CO)} _{5}$ is diamagnetic
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fe(CO)5 is a 18-electron complex with a trigonal bipyramidal structure. All electrons are paired in the d-orbitals, making it diamagnetic.