Tag: coordination chemistry

Questions Related to coordination chemistry

The π acid ligands donate their lone pairs to the metal to form a normal σ bond with the latter in addition to it, the vacant orbitals accept e− from the filled metal orbitals to form a type of π−bond which supplements the σ bond.

Which of the following has lowest C-O bond length ?
chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. $[Ni(CO) _4]$

  2. $[Co(CO) _4]^{-}$

  3. $[Fe(CO) _4]^{2-}$

  4. $[Mn(CO) _6]^+$

Show answer
Correct Option: D
Explanation:

This type of bonding where a metal is bonded with the carbon of a carbonyl compound is known as synergic bonding. In a metal carbonyl, the M-C bond has both σ and π character. The ligand donates eΘ pair to the central metal atom, and simultaneously accepts eΘ pair from central metal atom through synergic bonding. Here, all the options are examples of organometallic compounds. Due to synergic bonding, the metal carbon bond strength increases and bond length decreases due to the partial double bond character. Thus, the C-O bond strength decreases and bond length increases and bond order of CO decreases as the number of antibonding electrons increase. Out of the four options, the option D has Mn+, implying that the electron donating nature among the options is minimum. Therefore, tendency of synergic bonding is minimum, and thus M-C bond length is maximum implying that C-O bond strength is maximum and C-O bond length is minimum.

The pi acceptor ligand are those which possess vacant $\pi$-orbitals in addition to the lone pairs of $e^-$,which of the following complex/ion has highest M-C bond order?

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. $[V(CO) _6]^{-}$

  2. $Fe(CO) _5$

  3. $Ni(CO) _4$

  4. $[Mn(CO) _6]^+$

Show answer
Correct Option: A

Which of the following complex/ion has lowest C-O bond order ?

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. $[V(CO) _6]^-$

  2. $Fe(CO) _5$

  3. $Ni(CO) _4$

  4. $[Mn(CO) _6]^+$

Show answer
Correct Option: A
Explanation:

There are vacant orbitals in central atom in $[V(CO) _6]-$ which results in synergic bonding. Due to synergic bonding between V and CO the bond length between C and O increases and Bond order is inversely proportional to bond length.

Which of the following complex/ion has highest C-O bond length ?

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. $[V(CO) _6]^-$

  2. $Fe(CO) _5$

  3. $Ni(CO) _4$

  4. $[Mn(CO) _6]^+$

Show answer
Correct Option: A
Explanation:

There are vacant orbitals in central atom in $[V(CO) _6]-$ which results in synergic bonding. Due to synergic bonding between V and CO the bond length between C and O increases.

The pi acceptor ligand are those which possess vacant $\pi$-orbitals in addition to the lone pairs of $e^-$which of the following complex/ion has lowest M-C bond length ?

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. $[V(CO) _6]^-$

  2. $Fe(CO) _5$

  3. $Ni(CO) _4$

  4. $[Mn(CO) _6]^+$

Show answer
Correct Option: A

In which of the following cases, the synergic bonding takes place at the n-orbital of the ligand ? 

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. [PtCl$ _3$(C$ _2$H$ _4$)]$^-$

  2. [Ni(PF$ _3$)$ _4$]

  3. [Cr(C$ _6$H$ _6$)$ _2$]

  4. [Fe($\pi$-C$ _5$H$ _5$)$ _2$]

Show answer
Correct Option: A,C,D

Which of the following is/are example( s) of $\sigma$-bonded organometallic compound ? 

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. Al$ _2$(CH$ _3$)$ _6$

  2. Pb(CH$ _3$)$ _4$

  3. Zn(C$ _2$H$ _5$)$ _2$

  4. Ferrocene

Show answer
Correct Option: A,B,C
Explanation:

Option (A),(B),(C) are correct.Ferrocene is example of organometallic compound but is not $\sigma$-bonded. Its formula is $Fe(C _5H _5) _2$. It is the prototypical metallocene, a type of organometallic chemical compound consisting of two cyclopentadienyl rings bound on opposite sides of a central metal atom. Such organometallic compounds are also known as sandwich compounds. Each cyclopentadienyl (Cp) ring is then allocated a single negative charge, bringing the number of -electrons on each ring to six, and thus making them aromatic. These twelve electrons (six from each ring) are then shared with the metal via covalent bonding. 

Which of the following statement(s) is/are incorrect ? 

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. Metal carbonyls are the examples of only $\sigma$-bonded organometallic complexes.

  2. Metal carbonyls are the examples of only $\pi$-bonded organometallic complexes.

  3. Metal carbonyls are the examples of organometallic complexes which involve both $\sigma$- and $\pi$-bonds between metal and carbon of the carbonyl group.

  4. Metal carbonyls involve both $\sigma$- and $\pi$-bonds between metal and oxygen of the carbonyl group.

Show answer
Correct Option: A,B,D

Among the following complexes, the C-O bond order is lowest in :

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. [Mn(CO)$ _6$]$^+$

  2. [Fe(CO)$ _5$]

  3. [Cr(CO)$ _6$]

  4. [V(CO)$ _6$]$^-$

Show answer
Correct Option: D

If the bond length of the C - O bond in CO is 1.128$\overset{o}{A}$ what is the value of the bond length in [Fe(CO)$ _5$] ?

chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

  1. $1.15$ $\overset{o}{A}$

  2. $1.128$ $\overset{o}{A}$

  3. $1.72$ $\overset{o}{A}$

  4. $1.118$ $\overset{o}{A}$

Show answer
Correct Option: D